Associations between proinflammatory cytokines in the synovial fluid and radiographic grading and pain-related scores in 47 consecutive patients with osteoarthritis of the knee

作者：Orita Sumihisa^*; Koshi Takana; Mitsuka Takeshi; Miyagi Masayuki; Inoue Gen; Arai Gen; Ishikawa Tetsuhiro; Hanaoka Eiji; Yamashita Keishi; Yamashita Masaomi; Eguchi Yawara; Toyone Tomoaki; Takahashi Kazuhisa; Ohtori Seiji

来源：BMC Musculoskeletal Disorders, 2011, 12(1): 144.

DOI：10.1186/1471-2474-12-144

Background: One of the sources of knee pain in osteoarthritis (OA) is believed to be related to local chronic inflammation of the knee joints, which involves the production of inflammatory cytokines such as tumor necrosis factor alpha (TNF alpha), interleukin (IL)-6, and nerve growth factor (NGF) in the synovial membrane, and these cytokines are believed to promote pathological OA. In the present study, correlations between proinflammatory cytokines in knee synovial fluid and radiographic changes and functional scores and pain scores among OA patients were examined.
Methods: Synovial fluid was harvested from the knees of 47 consecutive OA patients, and the levels of TNF alpha, IL-6, and NGF were measured using enzyme-linked immunosorbent assays. Osteoarthritic knees were classified using Kellgren-Lawrence (KL) grading (1-4). The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) was used to assess self-reported physical function, pain, and stiffness.
Results: TNF alpha and IL-6 were detectable in knee synovial, whereas NGF was not. TNF alpha was not correlated with the KL grade, whereas IL-6 had a significantly negative correlation. We observed differences in the correlations between TNF alpha and IL-6 with WOMAC scores and their subscales (pain, stiffness, and physical function). TNF alpha exhibited a significant correlation with the total score and its 3 subscales, whereas IL-6 exhibited a moderately significant negative correlation only with the subscale of stiffness.
Conclusions: The present study demonstrated that the concentrations of proinflammatory cytokines are correlated with KL grades and WOMAC scores in patients with knee OA. Although TNF alpha did not have a significant correlation with the radiographic grading, it was significantly associated with the WOMAC score. IL-6 had a significant negative correlation with the KL grading, whereas it had only a weakly significant correlation with the subscore of stiffness. The results suggest that these cytokines play a role in the pathogenesis of synovitis in osteoarthritic knees in different ways: TNF alpha is correlated with pain, whereas IL-6 is correlated with joint function.

• 出版日期2011-6-30