Absence of mitochondrial dysfunction in polymyalgia rheumatica. Evidence based on a simultaneous molecular and biochemical approach.
OBJECTIVE
To investigate the molecular and biochemical profile of skeletal muscle mitochondria of patients with isolated polymyalgia rheumatica (PMR).


METHODS
We included patients with a recent diagnosis of PMR and as control healthy individuals submitted to orthopedic surgery. Skeletal muscle was obtained from quadriceps, thus was mitochondria immediately isolated. Long polymerase chain reaction and Southern blot transference were performed to detect deleted mtDNA molecules. Mitochondrial oxidative activity using different substrates and individual enzyme activity of respiratory chain complexes were assessed to search for any biochemical dysfunction.


RESULTS
Fifty-one individuals (PMR=25, controls=26) were included. Mean age was 72 (11) years; 45% were females. We found no significant increase of deleted mtDNA molecules in PMR patients compared to controls. Both groups differed neither on oxygen consumption (p=NS for all substrates) nor enzymatic activity (p=NS for all complexes).


CONCLUSIONS
Skeletal muscle mitochondria are molecularly and biochemically unaffected in PMR.
Miró
O
O
Department of Internal Medicine, Hospital Clínic, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Medical School, University of Barcelona, Spain.
Jarreta
D
D
Casademont
J
J
Barrientos
A
A
Rodríguez
B
B
Gómez
M
M
Nunes
V
V
Urbano-Márquez
A
A
Cardellach
F
F
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000368:Aged; D002352:Carrier Proteins; D004272:DNA, Mitochondrial / Q000235:genetics*; D042963:Electron Transport Complex II; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000378:metabolism*; D025261:Mitochondrial Proton-Translocating ATPases; D009097:Multienzyme Complexes / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D010085:Oxidative Phosphorylation; D010088:Oxidoreductases / Q000378:metabolism; D010101:Oxygen Consumption; D016133:Polymerase Chain Reaction; D011111:Polymyalgia Rheumatica / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D012016:Reference Values; D017384:Sequence Deletion; D013385:Succinate Dehydrogenase / Q000378:metabolism
D002352:Carrier Proteins; D004272:DNA, Mitochondrial; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D003576:Electron Transport Complex IV; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases; D014450:Electron Transport Complex III; C020439:oligomycin sensitivity-conferring protein