Involvement of prostaglandins from rheumatoid synovium in inhibition of articular cartilage metabolism

Abstract

Short term incubations of articular cartilage in media from cultures of rheumatoid synovial tissue result in marked inhibition of ³H-glycine and Na₂³⁵SO₄ incorporation into trichloroacetic acid (TCA) insoluble macro-molecules by the cartilage segments with little effect on degradation of prelabeled cartilage matrix. This inhibition is time dependent and not observed in cartilage segments incubated in media derived from rheumatoid synovia cultured in the presence of indomethacin (a specific inhibitor of prostaglandin synthesis). In addition, no indomethacin-sensitive cartilage inhibitory activity was detectable in media from cultures of normal synovia. The ether solubility of the majority of the inhibitory activity and the indomethacin sensitivity suggest that the inhibitor(s) are prostaglandins. The significance of prostaglandin-induced cartilage inhibitory activity derived from rheumatoid synovial tissue remains speculative. However, these data suggest that prostaglandins may play a substantial role in the development of cartilaginous lesions in inflammatory arthritis in which elevated prostaglandin levels are commonly found in the synovial fluid.