Mitochondrial dysfunction activates cyclooxygenase 2 expression in cultured normal human chondrocytes

Area of Science:

• Cell Biology
• Biochemistry
• Pathology

Background:

• Mitochondrial alterations are implicated in osteoarthritis (OA) pathogenesis.
• Mitochondrial respiratory chain (MRC) dysfunction may contribute to chondrocyte inflammation.

Purpose of the Study:

• To investigate the role of MRC dysfunction in the inflammatory response of human chondrocytes.
• To examine the mechanisms linking MRC dysfunction to prostaglandin E(2) (PGE(2)) production.

Main Methods:

• Induce mitochondrial dysfunction in human chondrocytes using MRC inhibitors (antimycin A, oligomycin).
• Measure PGE(2) levels, cyclooxygenase-2 (COX-2) and COX-1 mRNA/protein expression.
• Assess reactive oxygen species (ROS) production and the effects of ROS, mitochondrial Ca(2+), and NF-kappaB inhibitors.

Main Results:

• Inhibition of MRC complexes III and V significantly increased PGE(2) and COX-2 expression.
• MRC inhibition led to increased ROS production, dependent on mitochondrial Ca(2+) accumulation.
• Antioxidants, vitamin E, and inhibitors of mitochondrial Ca(2+) and NF-kappaB reduced PGE(2) and COX-2 levels.

Conclusions:

• MRC dysfunction in human chondrocytes induces an inflammatory response.
• PGE(2) production is mediated by mitochondrial Ca(2+) exchange, ROS generation, and NF-kappaB activation.
• These findings offer insights into mitochondria's role in OA pathogenesis.