Collagenase-1 (MMP-1) activity in equine synovial fluid: influence of age, joint pathology, exercise and repeated arthrocentesis.

The research investigates the enrolment of the enzyme Matrix metalloproteinases-1 (MMP-1) in horse joint fluid during different life stages, physical activity or disease. The study observes a potential for using MMP-1 as a biochemical marker for early detection of joint disease like osteoarthritis.

Introduction and Objective

• This research undertook an in-depth study of MMP-1, an enzyme belonging to the Matrix metalloproteinases (MMPs) family and its activity in equine (horse) synovial fluid (SF). SF is the fluid found in the cavities of synovial joints.
• MMPs are responsible for the breakdown of extracellular matrix in normal physiological processes such as embryonic development, reproduction, and tissue remodelling. In particular, collagenases like MMP-1 are of interest due to their distinct role in the breakdown of articular cartilage. This is significant because the malfunction of such can lead to chronic degenerative diseases like osteoarthritis (OA).
• A careful analysis of MMP-1 activity was performed at different stages of equine development and in animals suffering from OA.
• Other influences, such as physical exercise and repeated arthrocentesis (procedure of puncturing the joint cavity to aspirate SF) were also considered with their impact on MMP-1 activity.

Methods

• MMP-1 activity was determined in normal joints of fetal, juvenile and mature horses, and in those suffering from OA.
• A fluorogenic peptide substrate, which sparkles when cleaved, was employed to detect MMP-1 activity.
• MMP-1 activity was also measured in SF from horses subjected to an exercise regimen and those subjected to repeated arthrocentesis.

Results

• The results highlighted an age-related decline in the SF levels of active MMP-1.
• It was observed that MMP-1 activity was 15-fold higher in fetal horses and significantly higher in juvenile horses than mature ones confirming high metabolic activity during rapid growth and differentiation in early stages of life.
• MMP-1 activity was found to be increased in SF of joints inflicted by OA which suggests pathological matrix degradation and confirms the potency of MMP-1 to serve as a marker for early onset of joint disease.
• Exercise did not affect MMP-1 activity in the SF. However, repeated arthrocentesis increased MMP-1 activity significantly, which implies the procedure might become a possible confounding factor in such studies.

Conclusions

• The analysis indicated that MMP-1 activity might be beneficial in diagnostic, therapeutic or prognostic studies in horses suspected of OA.
• However, care must be taken to exclude variations in MMP-1 activity caused by physiological processes such as growth and development, or by clinical interventions such as repeated arthrocentesis.