Exercise Capacity of Patients with Dermatomyosis

Exercise Capacity of Patients with Dermatomyosisthe Role of Muscle Mitochondria and Reactive Oxygen Species

Dermatomyositis (DM) patients experience muscle weakness and low aerobic capacities, which are associated with poor health status and increased mortality. The origin of this muscle impairment remains unknown.

The investigators hypothesize that mitochondria functioning is impaired in DM muscle and links with exercise capacities.

Inclusion Criteria:

• Woman or man> 18 years,
• Signature of informed consent,
• Muscle biopsy for suspicion of recent inflammatory myopathy (<6 months) or for exclusion of neuromuscular pathology.

Prospectively, following the results of the muscle biopsy, the subjects will divided into three groups meeting the following criteria:

• "DM" group: DM according to the ENMC criteria;
• "other inflammatory myopathy" group: polymyositis, autoimmune necrotizing myopathy, non-specific myositis or inclusion myositis according to the ENMC criteria;
• Group "no neuromuscular pathology": i) myalgia and / or intolerance to exercise and ii) normal neuromuscular examination, iii) no increase in blood creatine kinase level, iv) absence of electromyographic abnormality, v) histological Muscle mass.

Exclusion Criteria:

• - Taking an immunomodulatory treatment within 6 months before inclusion,
• Paraneoplastic form of the disease,
• Presence of associated interstitial pneumonitis,
• Neuromuscular pathology different from inflammatory myopathy,
• Unbalanced cardiovascular disease,
• Impossibility of giving the subject informed information (subject in an emergency situation, difficulty in understanding the subject, ...),
• Subject under safeguard of justice,
• Subject under tutelage or under curators,
• Pregnancy (positive pregnancy test)
• Breastfeeding.