Alterations in a cartilage matrix glycoprotein in canine osteoarthritis

A number of biochemical abnormalities have been described in osteoarthritic (OA) cartilage, but little study has been devoted to changes in the noncollagenous, nonproteoglycan proteins of cartilage in this condition. Using a canine model of OA produced by transection of the anterior cruciate ligament of the knee, we have demonstrated that distinct alterations occur in a 550,000-dalton cartilage matrix glycoprotein in OA canine cartilage. This protein is a major protein constituent of normal articular cartilage. Fragments which are immunologically cross-reactive with the 550,000-dalton protein were more abundant in OA cartilage than in normal articular cartilage. Immunofluorescence studies revealed that staining with specific antiserum to the protein was absent in OA cartilage. This was the only noncollagenous, nonproteoglycan protein noted to undergo significant changes in this model of OA.