title: Mitochondrial respiratory activity is altered in osteoarthritic human articular chondrocytes.
abstract: OBJECTIVE
  Osteoarthritis (OA) is a degenerative rheumatic disease that is associated with extracellular matrix degradation and chondrocyte apoptosis in the articular cartilage. The role of mitochondria in degenerative diseases is widely recognized. We undertook this study to evaluate mitochondrial function in normal and OA chondrocytes and to examine age-related changes in mitochondria.
  
  
  METHODS
  Mitochondrial function was evaluated by analyzing respiratory chain enzyme complexes and citrate synthase (CS) activities as well as changes in mitochondrial membrane potential (Delta Psi m). The activities of mitochondrial respiratory chain complexes (complex I: rotenone-sensitive NADH-coenzyme Q(1) reductase; complex II: succinate dehydrogenase; complex III: antimycin-sensitive ubiquinol cytochrome c reductase; and complex IV: cytochrome c oxidase) and CS were measured in human articular chondrocytes isolated from OA and normal cartilage. Delta Psi m was measured by JC-1 using flow cytometry. Statistical analysis was performed using the Mann-Whitney U test and Student's t-test as well as several models of multiple linear regression.
  
  
  RESULTS
  OA articular chondrocytes had reduced activities of complexes II and III compared with cells from normal cartilage. However, the mitochondrial mass was increased in OA. Cultures of OA chondrocytes contained a higher proportion of cells with de-energized mitochondria. We found no relationship between mitochondrial function and donor age either in normal or in OA chondrocytes.
  
  
  CONCLUSIONS
  These findings suggest the involvement of mitochondrial function in the pathophysiology of OA. Cartilage degradation by OA and cartilage aging may be two different processes.
authors.affiliation: CHU Juan Canalejo, Coruña, Spain.
authors.forename: Emilia
authors.initials: E
authors.lastname: Maneiro
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Martín
authors.forename: María C
authors.initials: MC
authors.lastname: de Andres
authors.forename: Maria J
authors.initials: MJ
authors.lastname: López-Armada
authors.forename: José L
authors.initials: JL
authors.lastname: Fernández-Sueiro
authors.forename: Pilar
authors.initials: P
authors.lastname: del Hoyo
authors.forename: Fausto
authors.initials: F
authors.lastname: Galdo
authors.forename: Joaquin
authors.initials: J
authors.lastname: Arenas
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Blanco
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000201:enzymology* / Q000473:pathology; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology; D019902:Chondrocytes / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007425:Intracellular Membranes / Q000502:physiology; D007719:Knee Joint; D008564:Membrane Potentials; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology*; D020370:Osteoarthritis, Knee / Q000201:enzymology* / Q000503:physiopathology
chemical_list: D004791:Enzyme Inhibitors