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Effect of forced and voluntary exercise on heart function in mice with low dystrophin levels
Abstracts / Neuromuscular Disorders 25 (2015) S184–S316 3
School of Medicine, Pittsburgh, USA; Scripps Florida, Jupiter, USA In Duchenne muscular dystrophy (DMD) patients and the mdx mouse model of DMD, chronic activation of the classical nuclear factor kB (NF-kB) pathway is a central mechanism of the pathogenesis that causes degeneration of muscle fibers, inflammation and fibrosis. Prior studies demonstrate that inhibition of IKK-mediated NF-kB activation using L-isomer NF-kB essential modulator (NEMO) binding domain (NBD) peptide-based approaches reduces muscle pathology in the mdx mouse. For our studies, the NBD peptide is synthesized as a fusion peptide with an eight lysine (8K) protein transduction domain to facilitate intra-cellular delivery. We hypothesized that D-isoform peptide could have a greater effect than the naturally occurring L-isoform peptide due to longer persistence of the D-isoform peptide in vivo. In this study, we compared systemic treatment with low (1 mg/kg) and high (10 mg/kg) doses of L- and D-isomer 8K-wild type-NBD peptide in mdx mice. Treatment with both L- or D-isoform 8K-wild type-NBD peptide resulted in decreased activation of NF-kB and improved histology in the skeletal muscle of the mdx mouse. However, we observed kidney toxicity, characterized by proteinuria, increased serum creatinine, activation of NF-kB and pathological changes in the kidney cortex, that was most severe with treatment with the D-isoform of 8K-wild type-NBD peptide. http://dx.doi.org/10.1016/j.nmd.2015.06.388
G.P.365 Effect of forced and voluntary exercise on muscle function and integrity in aged mice expressing low dystrophin levels M. van Putten *, B. Kogelman, R. Werring, C. Tanganyika-de Winter, L. van der Weerd, A. Aartsma-Rus Leiden University Medical Center, Leiden, The Netherlands
S295
M. van Putten *, B. Kogelman, C. Tanganyika-de Winter, R. Werring, M. Hulsker, L. van der Weerd, A. Aartsma-Rus Leiden University Medical Center, Leiden, The Netherlands Duchenne muscular dystrophy patients lack dystrophin due to mutations in the X-chromosomal DMD gene. Patients develop severe heart failure, often leading to death. Several therapeutic approaches aiming at dystrophin restoration are in clinical trials, resulting in dystrophin restoration in skeletal muscle, while the heart appears more difficult to target. We here investigated the effects of different types of exercise on heart function and pathology in mice expressing low dystrophin levels (1–20%) in skeletal muscle and heart due to skewed X-inactivation (mdx-XistΔhs). We subjected 15.5 month old mdx-XistΔhs mice, mdx mice and two wild type mouse strains (C57BL/10ScSnJ and XistΔhs) to either treadmill running (twice weekly, 8 m/min 30 min), voluntary wheel running (total of 28 nights) or no exercise for a duration of 2 months. Ejection fraction, cardiac output, stroke volume and end-diastolic volume of the left and right ventricles and dilatation of the aortic arch were assessed at the age of 18 months. Additionally, fibrosis was visualized upon intravenous administration of the contrast solution Dotarem. Cardiac hypertrophy was observed in all mdx mice, regardless of the exercise regime, while this was prevented in a dystrophin level dependent manner in the mdx-XistΔhs mice. Collagen infiltration in the heart was also partly prevented in the mdx-XistΔhs mice, independently of the exercise type mdx-XistΔhsmice were subjected to. Expression levels of genes involved in heart function, immunological and fibrotic process assessments are pending. These data will unravel the consequences of low and high intensity exercise on heart function and pathology in mdx mice and highlight the protective effects of low dystrophin levels in the heart. http://dx.doi.org/10.1016/j.nmd.2015.06.390
NEXT GENERATION SEQUENCING Duchenne muscular dystrophy is an X-linked myopathy caused by a lack of dystrophin. Several therapeutic approaches aiming at dystrophin restoration are under investigation. Which dystrophin levels are needed to preserve muscle integrity during exposure to low or high intensity exercise is unknown. To study this, we subjected 15.5 month old mdx-XistΔhs mice, expressing low dystrophin levels (1–47%) based on non-random X-inactivation, mdx mice and two wild type strains (C57BL/10ScSnJ and XistΔhs) to either treadmill exercise (twice weekly 30 min 8 m/min), voluntary wheel running (total of 28 nights) or no exercise for two months. Subsequently, skeletal muscle function was assessed with a two week functional test regime. We observed a dystrophin level dependent increase in distance ran on the wheel, and in functional performance in fore-limb grip strength and wire and grid hanging tests in the mdx-XistΔhs mice. Voluntary wheel running improved wire and grid hanging performance in both dystrophic strains. Treadmill running did not influence functional performance in any of the strains. Plasma creatine kinase levels assessed at 18 months of age were low (<500U/L) for all strains, except for exercised mdx mice where levels were elevated (1537U/L treadmill running and 976U/L wheel running). In the quadriceps of mdx mice we found fibrosis and interestingly also extensive stripes of fatty infiltration, which was especially pronounced in exercised mice. Expression of low dystrophin levels partly prevented this. Less pronounced histopathology was found in wild type mice. Gene expression studies are pending. Our data suggest that treadmill exercise was not very deleterious for mdx mice, possibly due to the slow speed applied to these older mice. Voluntary exercise was beneficial for both mdx and mdx-XistΔhs mice. Dystrophin level dependent improvement in muscle function and integrity was observed in mdx-XistΔhs mice independent of the exercise applied. http://dx.doi.org/10.1016/j.nmd.2015.06.389
G.P.366 Effect of forced and voluntary exercise on heart function in mice with low dystrophin levels
G.P.367 Muscle MRI correlates with histology and clinical features in patients with FSHD, OPMD and sIBM S. Lassche *,1, M. Schyns 1, N. Koster 2, L. Heskamp 3, A. Heerschap 3, B. Kusters 2, N. Voermans 1, B. van Engelen 1 1 Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands; 2 Pathology, Radboud University Medical Centre, Nijmegen, The Netherlands; 3 Radiology, Radboud University Medical Centre, Nijmegen, The Netherlands Muscle biopsy has been the gold standard in diagnosing skeletal muscle diseases for decades. However, it is an invasive procedure with risk of sampling error. In contrast, muscle MRI is non-invasive and provides an overall image of disease pattern and severity. This makes MRI an attractive alternative for diagnosis and follow-up. However, the correlation between MRI, histology and clinical features remains relatively unknown. This study aims to determine in which way MRI changes correlate with histology and clinical features. We included 36 patients with facioscapulohumeral muscular dystrophy (FSHD), oculopharyngeal muscular dystrophy (OPMD) or sporadic inclusion body myositis (sIBM) and 12 controls. Manual muscle testing, quantitative force measurements, 6-minute walking test and Motor Function Measure (MFM) were performed to evaluate muscle strength and clinical performance. Muscle MRI of the upper and lower leg and a muscle biopsy of the vastus lateralis (VL) and the tibialis anterior (TA) muscles were obtained from each participant. MRI T2 fat fraction was determined quantitatively, dystrophic changes were evaluated using a standardized scale. Correlations were determined using Pearson’s correlation coefficient (r) or Spearman’s rank correlation coefficient (rs). MRI fat fraction correlated well with dystrophic changes in VL (rs = 0.55; P < 0.001) and TA biopsies (rs = 0.59; P < 0.001). A strong correlation was found between MRI changes and clinical parameters (e.g. MRI fat fraction vs. MFM D1 scale of TA: r = −0.76; P < 0.001). A lower correlation was found between dystrophic changes and clinical features (e.g. dystrophic changes vs. MFM D1 scale of TA: rs = −0.54; P < 0.01). This study provides a detailed
School of Medicine, Pittsburgh, USA; Scripps Florida, Jupiter, USA In Duchenne muscular dystrophy (DMD) patients and the mdx mouse model of DMD, chronic activation of the classical nuclear factor kB (NF-kB) pathway is a central mechanism of the pathogenesis that causes degeneration of muscle fibers, inflammation and fibrosis. Prior studies demonstrate that inhibition of IKK-mediated NF-kB activation using L-isomer NF-kB essential modulator (NEMO) binding domain (NBD) peptide-based approaches reduces muscle pathology in the mdx mouse. For our studies, the NBD peptide is synthesized as a fusion peptide with an eight lysine (8K) protein transduction domain to facilitate intra-cellular delivery. We hypothesized that D-isoform peptide could have a greater effect than the naturally occurring L-isoform peptide due to longer persistence of the D-isoform peptide in vivo. In this study, we compared systemic treatment with low (1 mg/kg) and high (10 mg/kg) doses of L- and D-isomer 8K-wild type-NBD peptide in mdx mice. Treatment with both L- or D-isoform 8K-wild type-NBD peptide resulted in decreased activation of NF-kB and improved histology in the skeletal muscle of the mdx mouse. However, we observed kidney toxicity, characterized by proteinuria, increased serum creatinine, activation of NF-kB and pathological changes in the kidney cortex, that was most severe with treatment with the D-isoform of 8K-wild type-NBD peptide. http://dx.doi.org/10.1016/j.nmd.2015.06.388
G.P.365 Effect of forced and voluntary exercise on muscle function and integrity in aged mice expressing low dystrophin levels M. van Putten *, B. Kogelman, R. Werring, C. Tanganyika-de Winter, L. van der Weerd, A. Aartsma-Rus Leiden University Medical Center, Leiden, The Netherlands
S295
M. van Putten *, B. Kogelman, C. Tanganyika-de Winter, R. Werring, M. Hulsker, L. van der Weerd, A. Aartsma-Rus Leiden University Medical Center, Leiden, The Netherlands Duchenne muscular dystrophy patients lack dystrophin due to mutations in the X-chromosomal DMD gene. Patients develop severe heart failure, often leading to death. Several therapeutic approaches aiming at dystrophin restoration are in clinical trials, resulting in dystrophin restoration in skeletal muscle, while the heart appears more difficult to target. We here investigated the effects of different types of exercise on heart function and pathology in mice expressing low dystrophin levels (1–20%) in skeletal muscle and heart due to skewed X-inactivation (mdx-XistΔhs). We subjected 15.5 month old mdx-XistΔhs mice, mdx mice and two wild type mouse strains (C57BL/10ScSnJ and XistΔhs) to either treadmill running (twice weekly, 8 m/min 30 min), voluntary wheel running (total of 28 nights) or no exercise for a duration of 2 months. Ejection fraction, cardiac output, stroke volume and end-diastolic volume of the left and right ventricles and dilatation of the aortic arch were assessed at the age of 18 months. Additionally, fibrosis was visualized upon intravenous administration of the contrast solution Dotarem. Cardiac hypertrophy was observed in all mdx mice, regardless of the exercise regime, while this was prevented in a dystrophin level dependent manner in the mdx-XistΔhs mice. Collagen infiltration in the heart was also partly prevented in the mdx-XistΔhs mice, independently of the exercise type mdx-XistΔhsmice were subjected to. Expression levels of genes involved in heart function, immunological and fibrotic process assessments are pending. These data will unravel the consequences of low and high intensity exercise on heart function and pathology in mdx mice and highlight the protective effects of low dystrophin levels in the heart. http://dx.doi.org/10.1016/j.nmd.2015.06.390
NEXT GENERATION SEQUENCING Duchenne muscular dystrophy is an X-linked myopathy caused by a lack of dystrophin. Several therapeutic approaches aiming at dystrophin restoration are under investigation. Which dystrophin levels are needed to preserve muscle integrity during exposure to low or high intensity exercise is unknown. To study this, we subjected 15.5 month old mdx-XistΔhs mice, expressing low dystrophin levels (1–47%) based on non-random X-inactivation, mdx mice and two wild type strains (C57BL/10ScSnJ and XistΔhs) to either treadmill exercise (twice weekly 30 min 8 m/min), voluntary wheel running (total of 28 nights) or no exercise for two months. Subsequently, skeletal muscle function was assessed with a two week functional test regime. We observed a dystrophin level dependent increase in distance ran on the wheel, and in functional performance in fore-limb grip strength and wire and grid hanging tests in the mdx-XistΔhs mice. Voluntary wheel running improved wire and grid hanging performance in both dystrophic strains. Treadmill running did not influence functional performance in any of the strains. Plasma creatine kinase levels assessed at 18 months of age were low (<500U/L) for all strains, except for exercised mdx mice where levels were elevated (1537U/L treadmill running and 976U/L wheel running). In the quadriceps of mdx mice we found fibrosis and interestingly also extensive stripes of fatty infiltration, which was especially pronounced in exercised mice. Expression of low dystrophin levels partly prevented this. Less pronounced histopathology was found in wild type mice. Gene expression studies are pending. Our data suggest that treadmill exercise was not very deleterious for mdx mice, possibly due to the slow speed applied to these older mice. Voluntary exercise was beneficial for both mdx and mdx-XistΔhs mice. Dystrophin level dependent improvement in muscle function and integrity was observed in mdx-XistΔhs mice independent of the exercise applied. http://dx.doi.org/10.1016/j.nmd.2015.06.389
G.P.366 Effect of forced and voluntary exercise on heart function in mice with low dystrophin levels
G.P.367 Muscle MRI correlates with histology and clinical features in patients with FSHD, OPMD and sIBM S. Lassche *,1, M. Schyns 1, N. Koster 2, L. Heskamp 3, A. Heerschap 3, B. Kusters 2, N. Voermans 1, B. van Engelen 1 1 Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands; 2 Pathology, Radboud University Medical Centre, Nijmegen, The Netherlands; 3 Radiology, Radboud University Medical Centre, Nijmegen, The Netherlands Muscle biopsy has been the gold standard in diagnosing skeletal muscle diseases for decades. However, it is an invasive procedure with risk of sampling error. In contrast, muscle MRI is non-invasive and provides an overall image of disease pattern and severity. This makes MRI an attractive alternative for diagnosis and follow-up. However, the correlation between MRI, histology and clinical features remains relatively unknown. This study aims to determine in which way MRI changes correlate with histology and clinical features. We included 36 patients with facioscapulohumeral muscular dystrophy (FSHD), oculopharyngeal muscular dystrophy (OPMD) or sporadic inclusion body myositis (sIBM) and 12 controls. Manual muscle testing, quantitative force measurements, 6-minute walking test and Motor Function Measure (MFM) were performed to evaluate muscle strength and clinical performance. Muscle MRI of the upper and lower leg and a muscle biopsy of the vastus lateralis (VL) and the tibialis anterior (TA) muscles were obtained from each participant. MRI T2 fat fraction was determined quantitatively, dystrophic changes were evaluated using a standardized scale. Correlations were determined using Pearson’s correlation coefficient (r) or Spearman’s rank correlation coefficient (rs). MRI fat fraction correlated well with dystrophic changes in VL (rs = 0.55; P < 0.001) and TA biopsies (rs = 0.59; P < 0.001). A strong correlation was found between MRI changes and clinical parameters (e.g. MRI fat fraction vs. MFM D1 scale of TA: r = −0.76; P < 0.001). A lower correlation was found between dystrophic changes and clinical features (e.g. dystrophic changes vs. MFM D1 scale of TA: rs = −0.54; P < 0.01). This study provides a detailed