[Effects of pathological synovial fluids on the metabolism of chondrocytes]

The purpose of this study was to clarify the mechanism of joint destruction in rheumatoid arthritis and osteoarthritis by observing the effects of the pathological synovial fluids on proteoglycan (PG) and collagen metabolism of chondrocytes. When chondrocytes from chick embryo were cultured with pathological synovial fluids, especially RA synovial fluid, biosynthesis of both proteoglycan and collagen of chondrocytes were found to increase in proportion to the amounts of pathological synovial fluids applied to the culture medium. Chondrocytes began to synthesize PG of small molecular size, approximately 70,000 in addition to PG of normal molecular size. It is noteworthy that the PG of small molecular size shows a shortening of the glycosaminoglycan link and core protein on undersulfation. These findings indicate that pathological synovial fluids disturb the biochemical regulation of the articular cartilage matrix by altering both PG and collagen metabolisms of chondrocytes.