Osteoarthritis early detection by studying synovial fluid

For the first time, researchers found a change in the glycosylation profile of lubricin in synovial fluid from osteoarthritic equine joints compared with healthy joints. This is not shown before in human research, partly due to experimental limitations of healthy human tissue.

Glycosylation is a reaction of enzymes that attaches carbohydrate to a protein. In osteoarthritic joints that process is different from healthy joints, causing changes on a molecular level. See image below.

Lubricin (proteoglycan 4) acts in the superficial articular cartilage and synovial fluid. It has a crucial role in continuance of cartilage homeostasis. It regulates the proliferation of synovial cells and protects superficial chondrocytes from death.

Synovial fluid was collected from 7 healthy horses, 7 horses with structural osteoarthritis lesions and 3 horses with osteochondral lesions in joints from which fluid was collected. Additionally, 1 post mortem horse was used for an in vitro cartilage model mimicking osteoarthritis, to examine the release and processing of lubricin.

The in vitro model showed higher secretion of lubricin in synovial fluid after trauma. This
may also explain how injury leads to decreased joint lubrication and reduces the superficial synovial layer which increases the chance of osteoarthritis

> E. Svala et al., Equine Veterinary Journal 0 (2015) 1–8. All rights reserved to 2015 EVJ Ltd. Click here for the Pubmed summary