[Show abstract][Hide abstract] ABSTRACT: We examined the effects of exercise on diaphragm degeneration and cardiomyopathy in dystrophin-deficient mdx mice. Mdx mice (11 months of age) were exercised (swimming) for 2 months to worsen diaphragm degeneration. Control mdx mice were kept sedentary. Morphological evaluation demonstrated increased fibrosis in the diaphragm of exercised mdx mice (33.3 ± 6.0% area of fibrosis) compared with control mdx mice (20.9 ± 1.7% area of fibrosis). Increased (26%) activity of MMP-2, a marker of fibrosis, was detected in the diaphragms from exercised mdx mice. Morphological evaluation of the heart demonstrated a 45% increase in fibrosis in the right ventricle (8.3 ± 0.6% in sedentary vs. 12.0 ± 0.6% of fibrosis in exercised) and in the left ventricle (35% increase) in the exercised mdx mice. The density of inflammatory cells-degenerating cardiomyocytes increased 95% in the right ventricle (2.3 ± 0.6 in sedentary vs. 4.5 ± 0.8 in exercised) and 71% in the left ventricle (1.4 ± 0.6 sedentary vs. 2.4 ± 0.5 exercised). The levels of both active MMP-2 and the pro-fibrotic factor transforming growth factor beta were elevated in the hearts of exercised compared with sedentary mdx mice. The wall thickness to lumen diameter ratio of the pulmonary trunk was significantly increased in the exercised mdx mice (0.11 ± 0.04 in sedentary vs. 0.28 ± 0.12 in exercised), as was the thickness of the right ventricle wall, which suggests the occurrence of pulmonary hypertension in those animals. It is suggested that diaphragm degeneration is a main contributor to right ventricle dystrophic pathology. These findings may be relevant for future interventional studies for Duchenne muscular dystrophy-associated cardiomyopathy.
Full-text · Article · Jan 2016 · Journal of Anatomy
[Show abstract][Hide abstract] ABSTRACT: In Duchenne muscular dystrophy (DMD), the search for new biomarkers to follow the evolution of the disease is of fundamental importance in the light of the evolving gene and pharmacological therapies. In addition to the lack of dystrophin, secondary events including changes in calcium levels, inflammation and fibrosis greatly contribute to DMD progression and the molecules involved in these events may represent potential biomarkers. In this study, we performed a comparative evaluation of the progression of dystrophy within muscles that are differently affected by dystrophy (diaphragm; DIA and quadriceps; QDR) or spared (intrinsic laryngeal muscles) using the mdx mice model of DMD. We assessed muscle levels of calsequestrin (calcium-related protein), tumour necrosis factor (TNF-α; pro-inflammatory cytokine), tumour growth factor (TGF-β; pro-fibrotic factor) and MyoD (muscle proliferation) vs. histopathology at early (1 and 4 months of age) and late (9 months of age) stages of dystrophy. Fibrosis was the primary feature in the DIA of mdx mice (9 months: 32% fibrosis), which was greater than in the QDR (9 months: 0.6% fibrosis). Muscle regeneration was the primary feature in the QDR (9 months: 90% of centrally nucleated fibres areas vs. 33% in the DIA). The QDR expressed higher levels of calsequestrin than the DIA. Laryngeal muscles showed normal levels of TNF-α, TGF-β and MyoD. A positive correlation between histopathology and cytokine levels was observed only in the diaphragm, suggesting that TNF-α and TGF-β serve as markers of dystrophy primarily for the diaphragm.
Full-text · Article · Oct 2015 · International Journal of Experimental Pathology
[Show abstract][Hide abstract] ABSTRACT: The standard therapy used in the treatment of Duchenne muscle dystrophy (DMD) is corticoids, such as deflazacort and prednisone. However, they have limited therapeutic value, and their combination with drugs already in use to treat other human diseases could potentially increase corticoid outcomes in DMD. In the present study, we evaluated whether a combined therapy of the corticoid deflazacort with doxycycline could result in greater improvement in mdx dystrophy than deflazacort alone. Deflazacort alone or deflazacort/doxycycline were administered for 36 days (starting on postnatal day 0) in drinking water. Histopathological, biochemical (creatine kinase), functional (forelimb muscle grip strength and fatigue) parameters and inflammatory markers (MMP-9, TNF-α, NF-kB) were evaluated in biceps brachii and diaphragm muscles of the mdx mice. The combined therapy was superior in improving the dystrophic phenotype compared to monotherapy. The primary results were observed in attenuating muscle fatigue, decreasing muscle total calcium and inflammatory markers and increasing β-dystroglycan, a main component of the dystrophin-protein complex. Furthermore, the combined therapy was effective in preventing the loss of body mass observed with deflazacort alone at this very early stage of therapy. The present study offers preclinical data to support further studies with deflazacort/doxycycline combined therapy in DMD clinical trials. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
No preview · Article · May 2015 · Clinical and Experimental Pharmacology and Physiology
[Show abstract][Hide abstract] ABSTRACT: Duchenne muscular dystrophy (DMD) is a devastating inherited neuromuscular disorder with an incidence of 1 in 3500 live male births. DMD is characterized by a mutation in the X-chromosome that leads to a lack of dystrophin in skeletal and cardiac muscles. In DMD and in the mdx mice model of DMD, the absence of dystrophin leads to sarcolemma instability, increased calcium influx and consequent myonecrosis. Abnormal calcium entry and buffering seem to play important roles in dystrophy pathology and stretch activated calcium channels, such as the transient receptor potential canonical channel 1 (TRPC1), greatly contribute to calcium changes in dystrophic fibers. In this study we investigated the effects of suramin, an anti-fibrotic agent on TRPC1 levels in the diaphragm of mdx mice, at later stages of the disease (11 months). We also investigated the effects of suramin of the levels of calsequestrin, the main calcium-binding protein of the endoplasmic reticulum. Mdx mice (8 months old) received intraperitoneal injections of suramin (60 mg/kg body weight), twice a week for 3 months. Control mdx mice (8 months old) were injected with saline. Western blot analysis showed that suramin decreased the levels of TRPC1 (2.3±0.2 in control vs 1.3±0.3 in suramin-mdx, p<0.05) and improved the levels of calsequestrin (0.5±0.1 in control vs 0.9±0.2 in suramin-mdx, p<0.05). Suramin also decreased muscle fiber total calcium (29% decrease as observed with inductively coupled plasma-optical emission spectrometry). The present results suggest that suramin, in addition to its anti-fibrotic action can ameliorate dystrophy in the mdx diaphragm, at later stages of the disease, by acting on calcium entry (TRPC1) and calcium binding (calsequestrin) mechanisms.
[Show abstract][Hide abstract] ABSTRACT: In Duchenne muscular dystrophy (DMD), lack of dystrophin leads to progressive skeletal muscle degeneration. Tumor necrosis factor-alpha (TNF-a) and transforming growth factor-beta (TGF-b) contribute to inflammation and fibrosis deposition and have been used as markers of dystrophy progression. Skeletal muscles are affected under different intensities, with the respiratory muscles being the most affected and some muscles, such as the intrinsic laryngeal, spared. We performed a comparative evaluation of dystrophy progression in the dystrophic diaphragm (DIA) and quadriceps (QDR) muscles in the mdx mice model of DMD. We used mdx and C57BL/10 (control) mice. We assessed their histopathological features (morphometric analysis) and molecular composition (TNF-a and TGF-b levels by Western blot) at ages 1, 4 and 9 months. Fibrosis was the main histopathological feature in mdx DIA, which increased over time (1 month: 1.8%, 4 months: 18.2%, 9 months: 32% of fibrosis), being significantly elevated in mdx DIA compared to mdx QDR (9 months: 9% of fibrosis). Conversely, muscle regeneration, as demonstrated by areas with centrally nucleated fibers, was the main feature of the mdx QDR (1 month: 10%, 4 months: 79%, 9 months: 90% of centrally nucleated fibers areas) and significantly elevated in comparison to mdx DIA (9 months: 66% of central nucleated areas). Inflammation-regeneration area was higher in QDR at 1 month (50% in QDR vs. 6.0% in DIA), reaching similar levels (about 3%) in both muscles, at 9 months. Mdx DIA presented higher levels of TNF-a and TGF-b compared to mdx QDR, from 4 months on. In mdx QDR, the levels of TNF-a and TGF-b were increased (compared to control) during dystrophy progression. Elevated levels of TNF-a and TGF-b correlated with dystrophy progression mainly in mdx DIA. We draw attention to the extensive regeneration in mdx QDR concomitantly to elevated levels of proinflammatory and profibrotic cytokines.
[Show abstract][Hide abstract] ABSTRACT: Introduction:
The purpose of this study was to better understand the beneficial effects of doxycycline on the dystrophic muscles of the mdx mouse.
Doxycycline (DOX) was administered for 36 days, starting on postnatal day 0, via drinking water. Untreated mdx mice received plain water for the same period and served as a control group.
DOX decreased the levels of metalloproteinase-9 and tumor necrosis factor-alpha in the biceps brachii and diaphragm of the mdx mice. It also reduced the total amount of calcium in the muscles studied, concomitant with an increase in the levels of calsequestrin 1.
The results show that DOX can affect factors that are important in dystrophic pathogenesis and highlight its potential as a readily accessible therapy in clinical trials for treatment of Duchenne muscular dystrophy.
[Show abstract][Hide abstract] ABSTRACT: Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease that causes respiratory failure that results in death at about 30 years of age. The lack of dystrophin in mdx mice, the experimental model of DMD, causes sarcolemma breakdown and increased calcium influx followed by necrosis and fibrosis. At later stages of disease, cardiac muscle is also affected and the dystrophic cardiomyopathy is characterized by cardiomyocyte hypertrophy, necrosis, myocardial fibrosis and ECG abnormalities. Previously, we demonstrated that suramin, an antifibrotic agent and purinergic P2 receptor antagonist, decreased fibrosis and improved cardiac function in mdx mice. In this study we add further information about the effects of suramin on cardiac muscle total calcium and on β-dystroglycan, a main component of the dystrophin-protein complex. Mdx mice (n=18; 8 months old) received intraperitoneal injections of suramin (60 mg/kg body weight), twice a week for 3 months. Control mdx mice (n=18; 8 months old) were injected with saline. Blood was obtained to determine cardiac creatine-kinase (CK-cardiac). Suramin decreased (61%) the total amount of cardiac calcium (determined by inductively coupled plasma-optical emission spectrometry) and there was a tendency to suramin to increase β-dystroglycan levels (12.5±3% in control vs. 13.7±2.7% in suramin-mdx). Western blot analysis showed that suramin decreased the levels of the transient receptor potential canonical channel 1 (3.1±0.1% in control vs. 2.4±0.3% in suramin-mdx, p<0.05), a component of the stretch-activated calcium channel. Concomitantly, suramin decreased (57%) cardiac-CK and cardiac troponin (7.8±3.8% in control vs. 3.4±1.5% in suramin-mdx, p<0.05). Overall, we demonstrate that suramin decreases cardiomyocyte necrosis, possibly by its ability to affect cardiac muscle total calcium and a calcium channel-related protein. Furthermore, suramin may have potential benefits in maintaining the structure of the dystrophin-protein complex
[Show abstract][Hide abstract] ABSTRACT: Introduction:
The purpose of this study was to determine the effects of suramin, an antifibrotic agent, on cardiac function and remodeling in mdx mice.
mdx mice (8 months old) received intraperitoneal injections of suramin twice a week for 3 months. Control mdx mice (8 months old) were injected with saline.
Suramin improved the electrocardiography profile with the main corrections seen in S- to R-wave ratio, PR interval, and Q amplitude, and a significant decrease in the cardiomyopathy index. Suramin decreased myocardial fibrosis, inflammation, and myonecrosis.
These findings suggest that suramin may be a new adjunctive therapy to help improve cardiomyopathy in DMD.
[Show abstract][Hide abstract] ABSTRACT: Duchenne Muscular Dystrophy (DMD) is a myopathy characterized by absence of
dystrophin protein which causes functional changes followed by necrosis of skeletal and cardiac
muscle fibers. Cardiomyopathy is the main cause of death due to progressive myocardial fibrosis
(MF). Therefore, treatments that prevent myonecrosis and progression of MF are important in
patients with DMD. The mdx mouse also features progressive MF and it has served as an
experimental model of cardiomyopathy in DMD. The aim of this study was to evaluate the
treatment effect of the drug pifithrin-alpha (PFT-α) on the processes of muscle cell necrosis and
MF. The mdx mice (n = 28) with eight months of age was used, divided into two experimental
groups: mdx PFT-α (n = 14) and mdx control group (n = 14). Also C57BL/10 animals were used
(n = 14) for untreated mdx control animals. The animals of PFT-α mdx group received doses of
2.2 mg / kg by intraperitoneal injections twice a week for fifteen weeks. The animals were
euthanized and the heart was collected and frozen for quantitative analysis of proteins MMP-2,
TGF-β1, TNF and NF-kB through the technique of western blotting. Blood was collected and
subjected to analysis of the total and cardiac enzyme creatine kinase (CK). Treatment with PFT-
α reduced levels of pro-inflammatory proteins MMP-2 (23%), TGF-β1 (60%), TNF (36%) and
NF-kB (30%) of the mdx PFT-α group compared to the untreated mdx control group. Also there
were decreased levels of total and cardiac CK in the blood plasma of the mdx PFT-α group
compared to the untreated mdx control group. It is concluded that treatment with PFT-α was
effective in reducing the pro-inflammatory proteins and may prevent or ameliorate the
development of MF.
[Show abstract][Hide abstract] ABSTRACT: Muscle degeneration and fibrosis are associated with inflammation in dystrophic
muscles of Duchenne muscular dystrophy (DMD) and in the mdx mice, a model of DMD.
Corticosteroids including deflazacort (DFZ) are still the gold standard therapy for DMD, in spite
of the relevant side effects. Combined drug interventions may be one therapeutic strategy for
complex diseases such as DMD. We evaluated, in mdx mice, the effect of a combined treatment
of DFZ with doxycycline (DOX), a potent inhibitor of matrix metalloproteinases (MMP), on the
some biomarkers involved in the pathogenesis of muscular dystrophy. DFZ (1.2mg/kg) and DOX
(6mg/ml) were administered either alone or in combination to mothers and newborns in drinking
water, for 36 days (starting on postnatal day 0). Effects were assessed in vivo and ex vivo
functional properties, histological and biochemical parameters. Biceps brachii (BB) and
diaphragm (DIA) muscles were removed. Histological analysis showed that each treatment
significantly attenuated myonecrosis and reduced inflammation in BB and DIA, a marked
complementary effect was observed with the combination DFZ/DOX. Both drugs significantly
decreased blood creatine kinase levels, however the benefit was greater for the DFZ/DOX
therapy. Total calcium content was significantly higher in mdx muscles than in control
C57Bl/10. Western blot analysis showed higher levels of MMP-9 and Tumor Necrosis Factor-α
(TNF-α) in mdx muscles compared to control C57Bl/10 mice. In the DFZ/DOX group the MMP-
9 expression was reduced 82% in BB (1,53± 0.35 vs 0,27±0.49) and 75% in DIA (5,06±1.41 vs
1,29±0.71) and TNF-α decreased respectively 64% and 79% compared to untreated mdx group.
Compared to untreated mdx mice the calsequestrin (CSQ1) expression in all treated groups
exhibited a significant increase in BB and DIA. The effect of therapy either alone or in
combination was the partial restoration of CSQ1 expression levels reaching those levels found in
non dystrophic muscles. In vivo, each treatment significantly increased forelimb strength and
decreased fatigue compared to that mdx mice. These results indicate that combined DFZ/DOX
may be a possible useful therapeutic alternative to ameliorate muscular dystrophy caused by
[Show abstract][Hide abstract] ABSTRACT: We examined whether diaphragm degeneration affects cardiac muscle
in dystrophin-deficient mdx mice. To worsen diaphragm degeneration, adult mdx mice were exercised (swim) for 1 h, 5 days a week,
for 2 months. One day after the last exercise, diaphragm and hearts
were analyzed by histopathology and western blot of metalloproteinase
(MMP) and tumor growth factor (TGF)-beta. Age matched
unexercised mdx served as controls. In mdx diaphragm, exercise
increased fibrosis (60 %) and the levels of active MMP-2, pre MMP-2
and pro MMP-2 (26, 28 and 12 % increase). In mdx heart, exercise
also lead to increased fibrosis (42 % higher than unexercised), higher
levels of TGF-b and of active MMP-2, pre MMP-2 and pro MMP-2
(32, 28 and 11 % increase) compared with unexercised mdx. Density
of inflammatory cells patches was almost twice higher in exercised
than unexercised mdx hearts. Right ventricle was significantly more
affected than the left ventricle: myocardial fibrosis was increased by
45 % (8.3 ± 0.6 in unexercised vs. 12.0 ± 0.6 in exercised) in the
right ventricle while in the left ventricle this increase was 35 %
(5.6 ± 0.7 unexercised vs. 7.6 ± 0.8 exercised). Inflammatory cells/
degenerating cardiomyocytes density was increased 95 % (2.3 ± 0.6
unexercised vs. 4.5 ± 0.8 in exercised) in the right ventricle against
71 % increase in left ventricle (1.4 ± 0.6 unexercised vs. 2.4 ± 0.5
exercised). While exercise promoted concomitant changes in the
dystrophic diaphragm and heart, the present results suggest that
degeneration of diaphragm may contribute, at least in part, to the
cardiac injury in dystrophin deficient mice.
[Show abstract][Hide abstract] ABSTRACT: We examined whether diaphragm degeneration affects cardiac muscle in dystrophin-deficient mdx mice. To worsen diaphragm degeneration, adult mdx mice were exercised (swim) for 1 hour, 5 days a week, for 2 months. One day after the last exercise, diaphragm and hearts were analyzed by histopathology an western blot of metalloproteinase (MMP) and tumor growth factor (TGF-beta). Age matched unexercised mdx served as controls. In mdx diaphragm, exercise increased fibrosis (60%) an the levels of active-MMP-2, pre-MMP-2 and pro-MMP-2 (26%, 28% and 12% increase). In mdx heart, exercise also lead to increase fibrosis (42% higher than unexercised), higher levels of TGF-b and of active-MMP-2, pre-MMP-2 and pro-MMP-2 (32%, 28% and 11% increase) compared with unexercised mdx. Density of inflammatory cells patches was almost twice higher in exercised than unexercised mdx hearts. Right ventricle was significantly more affected than the left ventricle: myocardial fibrosis was increases by 45% (8.3±0.6 in unexercised vs. 12±0.6 in exercised) in the right ventricle while in the left ventricle this increase was 35% (5.6±0.7 unexercised vs. 7.6±0.8 exercised). Inflammatory cells/degenerating cardiomyocytes density was increased 95% (2.3±0.6 unexercised vs. 4.5±0.8 in exercised) in the right ventricle against 71% increase in left ventricle (1.4±0.6 unexercised vs. 2.4±0.5 exercised). while exercise protocol promoted concomitant changes in the dystrophic diaphragm and heart, the present results suggest that degeneration of diaphragm may contribute, at least in part, to the cardiac injury in dystrophin deficient mice.
[Show abstract][Hide abstract] ABSTRACT: In dystrophic mdx mice and in Duchenne muscular dystrophy, inflammation contributes to myonecrosis. Previously, we demonstrated that eicosapentaenoic acid (EPA) decreased inflammation and necrosis in dystrophic muscle. In the present study, we examined the effects of EPA and the corticoid deflazacort (DFZ) as modulators of M1 (iNOS-expressing cells) and M2 (CD206-expressing cells) macrophages. Mdx mice (14days old) received EPA or DFZ for 16days. The diaphragm, biceps brachii and quadriceps muscles were studied. Immunofluorescence, immunoblotting and ELISA assays showed that EPA increased interleucin-10, reduced interferon-γ and was more effective than DFZ in promoting a shift from M1 to M2.
No preview · Article · Sep 2013 · Journal of neuroimmunology
[Show abstract][Hide abstract] ABSTRACT: Background & aims:
In Duchenne muscular dystrophy (DMD) and in the mdx mouse model of DMD, the lack of dystrophin leads to muscle degeneration and inflammation contributes to progression of the disease. In this study, we evaluated the effects of commercially available fish oil containing EPA and docosahexaenoic acid (DHA) on mdx.
Mdx mice (14 days old) were treated with fish oil (FDC Vitamins; 0.002 g EPA and 0.001 g DHA) for 16 days by gavage. Control mdx mice received mineral oil (Nujol). Grip strength measurement was used for functional evaluation. The sternomastoid, diaphragm and biceps brachii muscles were removed and processed for histopathology and Western blot analysis.
Fish oil decreased creatine kinase and myonecrosis. In all muscles studied, the inflammatory area was significantly reduced after treatment (18.0 ± 3.0% inflammatory area in untreated mdx mice versus 4.0 ± 1% in treated mdx mice). Fish oil protected against the loss of muscle strength. Fish oil significantly reduced the levels of TNF-α and the levels of 4-HNE-protein adducts (30-34% reduction for both) in all muscles studied.
Commercially available fish oil may be potentially useful to ameliorate dystrophic progression of skeletal muscles, deserving further clinical trials in DMD patients.
No preview · Article · Nov 2012 · Clinical nutrition (Edinburgh, Scotland)
[Show abstract][Hide abstract] ABSTRACT: Introduction:
In Duchenne muscular dystrophy and in the mdx mouse, muscle fiber degeneration and subsequent fibrosis lead to cardiorespiratory failure. Previously, we demonstrated that the anti-fibrotic agent suramin was effective in decreasing fibrosis in mdx muscles. In this study, we were interested to see whether suramin could affect metalloproteinases (MMP) and improve the functional activity of the mdx diaphragm muscle.
Zymography was performed to evaluate MMP-2 and MMP-9 activity. Western blotting was used to analyze the levels of beta-dystroglycan. Muscle function was assessed in hemidiaphragm in vitro preparations.
We found that suramin affects metalloproteinase-9 activity and increases beta-dystroglycan. Furthermore, suramin also protects against diaphragm muscle fatigue over time.
These results show the potential benefits of suramin in maintaining the structure of the dystrophin-glycoprotein complex.
[Show abstract][Hide abstract] ABSTRACT: A fibrose e as alterações eletrocardiográficas são características patológicas observadas no coração de pacientes com Distrofia Muscular de Duchenne (DMD) e no camundongo mdx, modelo da DMD. Objetivamos correlacionar a fibrose cardíaca com a mudança temporal nos parâmetros eletrocardiográficos e o nível da citocina pró-fibrótica (TGF-b1) na evolução da cardiomiopatia em camundongos mdx. Foram utilizados camundongos mdx de ambos os sexos, com idades de 11, 13 e 17 meses. A avaliação funcional foi realizada in vivo com eletrocardiógrafo na derivação DII. O músculo cardíaco foi dissecado para análise histopatológica com tricrômico de Masson e os níveis de TGF-b1 foram avaliados por Western blot. A análise histopatológica mostrou aumento progressivo da fibrose miocárdica com a idade. Aos 17 meses a fibrose cardíaca alcançou 13,1±3,9% um aumento significativo com as demais idades (mdx-11 meses 6,1±1,0%; mdx-13 meses 8,6±1,2%, p<0.05 ANOVA). Os níveis de TGF-b1 estão aumentados nos estágios intermediários da cardiomiopatia, atingindo um pico aos 13 meses (3,0±0,7%) seguido de redução significativa aos 17 meses (1,8±0,3%, p<0.01 ANOVA). Os parâmetros eletrocardiográficos revelaram comprometimento da condução do impulso elétrico no coração distrófico com a progressão da fibrose. O índice de cardiomiopatia dado pela razão dos intervalos QT/PQ foi maior aos 17 meses (1,5±0,1), um aumento de 79% e 48% comparados com as idades de 11 e 13 meses respectivamente (p<0.01 ANOVA). O traçado eletrocardiográfico demonstrou prolongamento do intervalo QRS, aprofundamento da onda Q e intervalo PR encurtado, em todas as idades. A fibrose miocárdica e as alterações eletrocardiográficas estão associadas com a evolução da cardiomiopatia em camundongos mdx. Os níveis de TGF-b1 podem não estar relacionados com a progressão temporal da fibrose.
[Show abstract][Hide abstract] ABSTRACT: We examined whether doxycycline, an antibiotic member of the tetracycline family, improves the histopathology and muscle function in mdx mice, the experimental model of DMD.
Doxycycline was administered for 36 days (starting on postnatal day 0) and for 9 months (starting at 8 months of age) in drinking water. Histopathological, biochemical (creatine kinase), and functional (forelimb muscle grip strength) parameters were evaluated in limb, diaphragm, and cardiac muscle.
Doxycycline significantly minimized the dystrophic phenotype of skeletal and cardiac muscles and improved forelimb muscle strength. The drug protected muscle fibers against myonecrosis and reduced inflammation. Furthermore, it slowed the progression of myocardial fibrosis.
This study provides evidence that doxycycline may be a potential therapeutic agent for DMD.
[Show abstract][Hide abstract] ABSTRACT: Background & aims:
Duchenne muscular dystrophy (DMD) is a genetic muscle disease caused by the absence of dystrophin. An established animal model of DMD is the mdx mouse, which is unable to express dystrophin. Inflammation, particularly the proinflammatory cytokine tumor necrosis factor alpha (TNF-α), strongly contributes to necrosis in the dystrophin-deficient fibers of the mdx mice and in DMD. In this study we investigated whether the antioxidant N-acetylcysteine (NAC) decreases TNF-α levels and protects the diaphragm muscle of mdx mice against necrosis.
Mdx mice (14 days old) received daily intraperitoneal injections of NAC for 14 days, followed by removal of the diaphragm muscle. Control mdx mice were injected with saline.
NAC reduced TNF-α and 4-HNE-protein adducts levels, inflammation, creatine kinase levels, and myonecrosis in diaphragm muscle.
NAC may be used as a complementary treatment for dystrophinopathies. However, clinical trials are needed to determine the appropriate dose for patients with Duchenne muscular dystrophy.