Evaluation of transforming growth factor beta 1 in dogs with osteoarthritis

Osteoarthritis is a common problem in daily veterinary practice with insufficient knowledge about disease mechanism. Because fibrosis is a part of the alteration in the effected joints, we investigated the transforming growth factor beta 1 (TGF-β1) as an important regulation molecule of tissue fibrosis. We chose Osteoarthritis following a cruciate ligament rupture (CLR) because it is a common model of osteoarthritis. A total of 13 healthy dogs and 38 dogs suffering from CLR were included in this prospective study. The concentration of TGF-β1 was measured in synovial fluid using the "Quantikine Human TGF-β1 Immunoassay" (Fa. R & D Systems, Minneapolis, USA). There was a significant difference in the TGF-β1 concentration of the synovial fluid of healthy compared to affected patients (p < 0.001). The synovial TGF-β1 concentration also correlated significantly (p = 0.0147) with the synovial viscosity of the affected patients. No significant correlations could be observed to duration of disease, severity of lameness and degree of joint swelling, but also to joint capsule sickness, osteophyte development and degeneration of joint cartilage. The results of our study show an increased TGF-β1 concentration in knees affected with osteoarthritis as consequence of CLR. So we can conclude that TGF-β1 takes part at the osteoarthritic remodelling process, but different phases of the remodelling process cannot be distinguished by the measurement of TGF-β1.