Synovial fluid gelatinase concentrations and matrix metalloproteinase and cytokine expression in naturally occurring joint disease in horses.

The research investigates the concentrations of matrix metalloproteinase (MMP)-2 and -9 in the synovial fluid and the level of mRNA expression of MMP-1, -13, and -3; interleukin[IL]-1alpha and beta; and tumor necrosis factor in the synovial membrane and articular cartilage in horses with naturally occurring joint disease. It found that MMP-2 and -3 are abundant in naturally occurring joint diseases and that inflmmatory cytokines interleukin-1beta and TNF-alpha might play a role in the onset of osteochondritis dissecans, a joint disorder.

Research Methodology

• The research involved the collection and analysis of synovial fluid, synovial membrane and articular cartilage from 5 healthy horses and 55 horses suffering from various joint diseases. The diseases were categorized as acute traumatic, chronic traumatic, osteochondritis dissecans (OCD), or septic conditions.
• Procedure involved the analysis of synovial fluid gelatinase concentrations using zymography, a technique used to study enzymatic activity.
• The mRNA expression for MMP-1, -3, and -13, IL-1alpha and beta, TNF-alpha, type-II collagen, and aggrecan in synovial membrane and articular cartilage were analyzed using quantitative reverse transcriptase-polymerase chain reaction, a technique employed to measure the amount of specific RNA in a sample.

Research Findings

• The MMP-2 concentration in the synovial fluid was significantly higher in diseased joints compared to healthy ones. Notably, septic joints exhibited a significantly higher concentration of pro and active MMP-9.
• Stromelysin-1, a type of enzyme, was present in the majority of synovial membrane and articular cartilage samples and its concentration was affected by age.
• Collagenases, enzymes that break down collagen, were infrequently expressed. Specifically, MMP-13 was only found in diseased joints.
• Elevated interleukin-1beta expression was observed in all OCD samples and was influenced by age.
• Tumor necrosis factor-alpha expression was significantly higher in cartilage from joints with acute traumatic and OCD conditions.
• No correlation was found between MMP or cytokines and the expression of type-II collagen or aggrecan, proteins that make up cartilage.

Conclusion

• MMP-2 and -3 were found to be abundant in naturally occurring joint diseases as well as normal joints. The study therefore identifies a characteristic profile of inflammation in joint diseases that involve the excess presence of MMP-2 and MMP-3.
• Interleukin-1beta and TNF-alpha may be vital in the pathogenesis of OCD, highlighting potential disease mechanisms and therapeutic targets.
• The concentrations of MMP and IL-1beta were found to be affected by age, suggesting that joint diseases might be more prevalent or severe in older horses.