Does protein kinase R mediate TNF-α- and ceramide-induced increases in expression and activation of matrix metalloproteinases in articular cartilage by a novel mechanism?

摘要: We investigated the role of proinflammatory cytokine TNF-α, second messenger C2-ceramide, and protein kinase R (PKR) in bovine articular cartilage degradation. Bovine explants were stimulated with C2-ceramide or TNF-α for 24 hours. To inhibit activation PKR, 2-aminopurine was added to duplicate cultures. Matrix metalloproteinase (MMP) expression medium analysed by gelatin zymography, proteoglycan release dimethylmethylene blue assay, cell viability Cytotox 96® assay. treatment resulted a significant both pro- active MMP-2 into medium. Small increases also seen treatment. Incubation before marked reduction MMP-9. significantly increased medium, which inhibited cotreatment 2-aminopurine. A loss observed when treated found be regulated PKR. have shown that result synthesis MMPs, proteoglycan, death. These effects are abrogated PKR inhibitor Collectively, these results suggest novel MMPs support our hypothesis its activator, PACT, implicated degradation occurs arthritic disease.