Anti-inflammatory drugs, prostanoid and proteoglycan production by cultured bovine articular chondrocytes

The effect of various anti-inflammatory drugs on the production of prostaglandins E2 and F2 alpha, 6 keto PGF1 alpha and thromboxane B2 by bovine articular chondrocytes was measured by radioimmunoassay. While indomethacin and meclofenamic acid caused a dose-dependent inhibition of all prostanoids measured, the effects of hydrocortisone and colchicine varied with respect to different prostanoids. Hydrocortisone (10(-7)M - 10(-13)M) both in the presence and absence of added arachidonic acid, resulted in an inhibition of prostaglandins E2 and F2 alpha, and to a lesser extent, 6 keto PGF 1 alpha, but TxB2 production was only slightly inhibited by the drug in the absence of arachidonic acid and markedly increased in its presence. Colchicine (10(-7)M-10(-3)M) had the opposite effect, causing an inhibition of TxB2 and stimulating PGE2 and 6 keto PGF1 alpha production. These findings suggest that certain anti-inflammatory drugs may, in addition to their action on phospholipase A2 and cyclo-oxygenases, exert potent effects at the level of the different synthetases. In order to see whether these alterations in relative prostanoid levels affected proteoglycan metabolism, the effect of anti-inflammatory drugs on proteoglycan synthesis by cultured chondrocytes was tested using 35SO4 labeling methodology. The results showed that at the concentrations tested (10(-5)M to 10(-7)M), indomethacin, dexamethasone, hydrocortisone and colchicine inhibited 35SO4 incorporation into newly synthesized proteoglycan molecules both in the presence (10(-6)M) and absence of exogenous arachidonic acid. In the same concentration range chloroquine had no effect. These results do not support the hypothesis of direct prostanoid involvement in the modulation of proteoglycan synthesis in articular cartilage.