MOLECULAR MECHANISMS OF INHIBITION OF COLLAGEN CLEAVAGE ACTIVITY BY DEFEROXAMINE IN THE CARTILAGE OF PATIENTS WITH OSTEOARTHRITIS

Abstract

Objective: to study the molecular mechanisms underlying the suppression of collagenase activity in the presence of deferoxamine (DFO) in articular cartilage explants from patients with osteoarthritis (OA).Subjects and methods. The knee joint cartilage obtained during arthroplasty from 33 patients (mean age, 61.8±10.3 years) with OA, and that derived at autopsy from 25 people (mean age 40±6.1 years) without this disease were investigated. The cartilage was cultured in the presence of 10 μm DFO. The gene expression in the cartilage explants was determined by real-time reverse transcriptase and polymerase chain reaction.Results and discussion. The reduced collagenase activity in the presence of DFO in the articular cartilage explants from patients with OA, which had been shown earlier, was accompanied by the significantly inhibited expression of matrix metalloproteinases 1 and 13 and cathepsin K, which had collagenase activity, as well as the marker of hypertrophic chondrocytes, such as X type collagen, and the proinflammatory cytokines interleukin-1β and tumor necrosis factor-α. DFO did not change the expression levels of the phosphoglucomutase and pyruvate kinase genes responsible for the production of adenosine triphosphate (ATP) during glycolysis and the glucose transporter Glut 1. On the contrary, the expression of the genes associated with ATP generation in the tricarboxylic acid cycle: isocitrate dehydrogenase, succinate dehydrogenase, α-ketoglutarate dehydrogenase, malate dehydrogenase, and adenosine monophosphate- activated protein kinase (AMPK) significantly increased. The expression of AMPK in the articular cartilage of patients with OA was significantly lower than that in healthy individuals.Conclusion. Inhibition of collagen cleavage in the presence of DFO in the articular cartilage explants from OA patients, which was accompanied by a considerable decrease in the expression of the proteases responsible for degradation of the extracellular matrix, proinflammatory cytokines and chondrocytes hypertrophy, was due to the enhanced activity of mitochondrial oxidative phosphorylation in the chondrocytes.

Keywords

• osteoarthritis
• gene expression
• articular cartilage explants
• proteases
• x type collagen
• proinflammatory cytokines
• glycolysis
• tricarboxylic acid cycle