Urotensin II (U-II), a novel cyclic peptide, possibly associated with the pathophysiology of osteoarthritis

Synovial fibrosis is one of the main outcomes of osteoarthritis. Some authors have reported that urotensin-II (U-II) may cause pathologic fibrosis in cardiovascular system, lung and liver. However there are no previous reports available in the literature about its relationship with the synovial fibrosis in osteoarthritis. The aim of this study was to compare the U-II levels in knee synovial fluids obtained from osteoarthritic and non-osteoarthritic patients. Two groups were created, the osteoarthritis group and non-osteoarthritic control group. The control group was consisted of patients who underwent arthroscopic surgery for other reasons than cartilage disorders. In the osteoarthritis group all patients had grade 4 primer degenerative osteoarthritis and were treated with total knee arthroplasty. Minimum 1 mL knee synovial fluids were obtained during operation. Levels of U-II were measured by using ELISA kit U-II levels were significantly higher in the osteoarthritic group than that in the control group. No correlation was found between U-II levels and age. In conclusion, the significantly high U-II levels in the knee synovial fluid of osteoarthritic patients supported our hypothesis that "U-II may be associated with the synovial fibrosis in osteoarthritis".