INDUCTION OF CYCLOOXYGENASE BY INTERLEUKIN-1 - COMPARATIVE-STUDY BETWEEN HUMAN SYNOVIAL-CELLS AND CHONDROCYTES

Objective. To investigate the regulation of the prostaglandin (PG) synthesis b Methods. Both cell types stimulated by human recombinant IL-1 synthesized PGE(2), PGF(2 alpha), and 6-keto-PGF(1 alpha). Results. PGE(2) was the major PG synthesized. When arachidonic acid was added exogenously at the end of the stimulation, an increase in the prostaglandin synthesis was observed after 6 and 24 h suggesting that cyclooxygenase is the limiting enzyme. Using actinomycin D and cycloheximide, PG synthesis was shown to be protein synthesis dependent. Inhibition of the constitutive cyclooxygenase by aspirin before the IL-1 stimulation confirmed that the increased prostaglandin synthesis was due to a de novo synthesis of cyclooxygenase. Conslusion. This enzyme induction by IL-1 was found to be similar in both cell types.