Evidence for altered synthesis of type II collagen in patients with osteoarthritis

There is evidence to suggest that the synthesis of type II collagen is incr eased in osteoarthritis (OA). Using an immunoassay, we show that the conten t of the C-propeptide of type II procollagen (CPII), released extracellular ly from the newly synthesized molecule, is directly related to the synthesi s of this molecule in healthy and osteoarthritic articular cartilages. In O A cartilage, CPII content is often markedly elevated (mean 7.6-fold), parti cularly in the mid and deep zones, reaching 29.6% of the content in newborn . Synthesis is also directly related to total collagen II content in OA, su ggesting its importance in maintaining collagen content and cartilage struc ture. The release of CPII from cartilage is correlated directly with cartil age content. However, the increase in CPII in OA cartilage is not reflected in serum, where a significant reduction is observed. Together these studie s provide evidence for alterations in procollagen II synthesis in vivo in p atients with OA.