Effects of indomethacin on the production of matrix metalloproteinase-3 and tissue inhibitor of metalloproteinases-1 by human articular chondrocytes.

OBJECTIVE

To study the action of indomethacin on cartilage catabolic activity by comparing the production of a matrix degrading proteinase and its inhibitor in human articular chondrocyte cultures.

METHODS

Matrix metalloproteinase-3 (MMP-3) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in conditioned medium from human articular chondrocyte cultures were measured using a one-step sandwich enzyme immunoassay. TIMP-1 mRNA expression was analyzed by Northern blotting using a 0.6 kb cDNA probe for human TIMP-1.

RESULTS

Human recombinant interleukin 1 beta (IL-1 beta) increased MMP-3 levels in primary chondrocyte cultures. Indomethacin at 10(-5) M inhibited this IL-1 beta stimulation, but had no effect in the therapeutic range (10(-6)-10(-7) M). Low levels of indomethacin (10(-7) M) significantly increased the production of TIMP-1 by chondrocytes. Synthesis of TIMP-1 appeared to be inhibited by prostaglandin E2 (PGE2), since exogenously added PGE2 reversed the stimulating effect of indomethacin on TIMP-1 production. Northern blot analysis showed that 10(-7) M indomethacin increased TIMP-1 mRNA levels in chondrocytes.

CONCLUSION

Our findings indicate that low levels of indomethacin can benefit matrix metabolism by affecting the balance of proteinases to their inhibitors in human articular cartilage.