Plasma and synovial fluid lysozyme activity in horses with experimental cartilage defects.

This research looks into the influence of cartilage defects on lysozyme activity within plasma and synovial fluid of horses, showing that increased lysozyme concentration in the synovial fluid is closely associated with joint injury or inflammation.

Study Method and Parameters

• The researchers created cartilaginous defects in the radiocarpal joints of 12 horses. Radiocarpal joint is one of the main weight-bearing joints in the limbs of a horse, thus a chosen site for this study.
• Post the creation of defects, various parameters inside the synovial fluid were actively monitored for the next 16 days. These parameters included lysozyme activity, beta-glucuronidase activity, and cytologic features.
• The study also compared the activity of plasma lysozyme and beta-glucuronidase, the synovial fluid lysozyme, beta-glucuronidase, and the leukocyte concentrations in the synovium.

Results of the Study

• The results indicated that plasma lysozyme activity was not influenced by synovial fluid lysozyme activity, meaning that the two aspects are independent of each other.
• Significantly increased activity of synovial fluid lysozyme was observed in joints that underwent surgery for induced defects as compared to the control group which only had arthrocentesis.
• However, there was no significant difference in the lysozyme activity between group I (with surgically induced defects) and sham-operated controls where only the cartilage was exposed.
• One of the critical outcomes of the study was the discovery of a positive correlation between increasing lysozyme concentration and increasing numbers of leukocytes in the synovial fluid. More leukocytes implies more inflammation in the joint area.
• The researchers also noticed parallel changes in the synovial fluid beta-glucuronidase activity. This indicates that a significant portion of the observed lysozyme activity in the synovial fluid originates from the lysosomes, not resulting from cartilage destruction.

Conclusions Analyzed

• Lysozyme activity within the synovial fluid was identified as a sensitive indicator of acute joint injury or inflammation, or both. This has a wide array of applications in diagnosing and managing joint disorders, not just in horses but also potentially in other mammals, including humans. Joint inflammation may be an early sign of various disorders including arthritis, which are better managed if diagnosed early.
• The research also confirms the importance of distinguishing the sources of lysozyme activity. As it showed that a large part of the lysozyme activity in synovial fluid is from lysosomal origin, this indicates that elevated lysozyme levels are more related to increased cellular activity or injury rather than cartilage break-down.