Discussion

Abstract

Proinflammatory cytokines have been postulated to be important mediators of inflammation and joint destruction in osteoarthritis (OA) and rheumatoid arthritis (RA).1Kaneyama K. Segami N. Nishimura M. et al.Importance of proinflammatory cytokines in synovial fluid from 121 joints with temporomandibular disorders.Br J Oral Maxillofac Surg. 2002; 40: 418Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar It remains controversial whether the analysis of synovial fluid can accurately portend the clinical status of temporomandibular joint (TMJ) disorders (TMDs), yet higher concentrations of the proinflammatory cytokines found in TMD patients are thought to reflect an activated immunologic network in the pathogenesis of TMD.1Kaneyama K. Segami N. Nishimura M. et al.Importance of proinflammatory cytokines in synovial fluid from 121 joints with temporomandibular disorders.Br J Oral Maxillofac Surg. 2002; 40: 418Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar This report represents an extension of a study on the same 100 patients/103 joints published in a 2001 study that considered the prognostic factors in internal derangement (ID) of the TMJ following arthrocentesis. A diverse study group with respect to age, duration of locking, ID, bony changes of the condyle, and mean follow-up was simplified by categorizing patients to 1 of 2 groups: comparison of proinflammatory cytokine levels in synovial fluid in successful and unsuccessful cases of TMJ arthrocentesis. Treatment success was arbitrarily defined to be an interincisal opening of greater than 38 mm and “no” to “minimal pain” on a visual analog scale. No presurgical data were made available with respect to these parameters of success for comparison. No attempt was made to correlate proinflammatory cytokine levels with respect to preoperative diagnostic categories. This was disappointing because the raw data were likely available to make such a correlation, lending a potential clinical application to this communication. Interleukin (IL)-6, thought to be produced by macrophages and T lymphocytes that infiltrate the synovium, as well as by chondrocytes and fibroblasts,1Kaneyama K. Segami N. Nishimura M. et al.Importance of proinflammatory cytokines in synovial fluid from 121 joints with temporomandibular disorders.Br J Oral Maxillofac Surg. 2002; 40: 418Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar, 2Hirano T. Matsuda T. Turner M. Miyasaka N. Excessive production of interleukin 6/B cell stimulatory factor-2 in rheumatoid arthritis.Eur J Immunol. 1988; 18: 1797Crossref PubMed Scopus (658) Google Scholar has been associated with joint synovitis and increased levels in joints showing degenerative bony changes in OA.1Kaneyama K. Segami N. Nishimura M. et al.Importance of proinflammatory cytokines in synovial fluid from 121 joints with temporomandibular disorders.Br J Oral Maxillofac Surg. 2002; 40: 418Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar IL-6 may also induce the release of proteinases that destroy the articular cartilage and cause bone resorption.1Kaneyama K. Segami N. Nishimura M. et al.Importance of proinflammatory cytokines in synovial fluid from 121 joints with temporomandibular disorders.Br J Oral Maxillofac Surg. 2002; 40: 418Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar, 3Sinmei M. Masuda K. Kikuchi T. et al.Interleukin 1, tumor necrosis factor, and interleukin 6 as mediators in cartilage destruction.Semin Arthritis Rheum. 1989; 18: 27Abstract Full Text PDF PubMed Google Scholar, 4Wilbrink B. Nietfeld J. Otter W. et al.Role of TNFα in relation to IL-1 and IL-6 in the proteoglycan turnover of human articular cartilage.Br J Rheumatol. 1991; 30: 265Crossref PubMed Scopus (45) Google Scholar Because the patient population in this study included a subset of 35 patients with joints showing bony changes of the condyle, such a preoperative diagnostic correlation could have proved interesting, especially for those of us who do not routinely send synovial fluid for analysis. Detection rates of IL-6 and concentration of IL-1β were reported to be statistically significant indicators of possible unsuccessful treatment following arthrocentesis for ID of the TMJ. The main role of IL-1β is destruction of the cartilage via degradation of proteoglycan.5Nishimura Segami N. Kaneyama K. et al.Proinflammatory cytokines and arthroscopic findings of patients with internal derangement and osteoarthritis of the temporomandibular joint.Br J Oral Maxillofac Surg. 2002; 40: 68Abstract Full Text PDF PubMed Scopus (67) Google Scholar, 6Arner E.C. Pratta M.A. Independent effects of interleukin-1 on proteoglycan breakdown, proteoglycan synthesis, and prostaglandin E2 release from cartilage in organ culture.Arthritis Rheumatol. 1989; 32: 288Crossref PubMed Scopus (121) Google Scholar, 7Okada Y. Shinmei M. Tanaka O. et al.Localization of matrix metalloproteinase 3 (stromelysin) in osteoarthritic cartilage and synovium.Lab Invest. 1992; 66: 680PubMed Google Scholar, 8Shinmei M. Masuda K. Kikuchi T. et al.The role of cytokines in chondrocyte mediated cartilage degradation.J Rheumatol. 1989; 16: 32Google Scholar, 9Shinmei M. Masuda K. Kikuchi T. et al.Interleukin 1, tumor necrosis factor, and interleukin 6 as mediators of cartilage destruction.Semin Arthritis Rheum. 1989; 18: 27Abstract Full Text PDF PubMed Scopus (80) Google Scholar, 10Saklatvala J. Tumor necrosis factor alpha stimulates resorption and inhibits synthesis of proteoglycan in cartilage.Nature. 1986; 322: 547Crossref PubMed Scopus (644) Google Scholar, 11Wilbrink B. Nietfeld J.J. Den Otter W. et al.Role of TNF alpha, in relation to IL-1 and IL-6 in the proteoglycan turnover of human articular cartilage.Br J Rheumatol. 1991; 30: 265Crossref PubMed Google Scholar, 12Henderson B. Pettipher E.R. Arthritogenic actions of recombinant IL-1 and tumor necrosis factor alpha in the rabbit Evidence for synergistic interactions between cytokines in vivo.Clin Exp Rheumatol. 1989; 75: 306Google Scholar The authors offered no explanation as to why the other measured proinflammatory cytokines (tumor necrosis factor-α, IL-8) were not found to be statistically relevant. This might be related to the rapid turnover or consumption of cytokines within the joint cavity5Nishimura Segami N. Kaneyama K. et al.Proinflammatory cytokines and arthroscopic findings of patients with internal derangement and osteoarthritis of the temporomandibular joint.Br J Oral Maxillofac Surg. 2002; 40: 68Abstract Full Text PDF PubMed Scopus (67) Google Scholar, 13Hopkins S.J. Humphreys M. Jayson M.I.V. Cytokines in synovial fluid. The presence of biologically active and immunoreactive IL-1.Clin Exp Immunol. 1988; 73: 422Google Scholar and the presence of cytokine receptor antagonists5Nishimura Segami N. Kaneyama K. et al.Proinflammatory cytokines and arthroscopic findings of patients with internal derangement and osteoarthritis of the temporomandibular joint.Br J Oral Maxillofac Surg. 2002; 40: 68Abstract Full Text PDF PubMed Scopus (67) Google Scholar, 14Neidel J. Schultze M. Lindschau J. Association between degree of bone-erosion and synovial fluid levels of tumor necrosis factor alpha in the knee-joints of patients with rheumatoid arthritis.Inflamm Res. 1995; 44: 217Crossref PubMed Scopus (88) Google Scholar, 15Fang P.K. Ma X.C. Ma D.L. et al.Determination of interleukin-1 receptor antagonist, interleukin-10, and transforming growth factor-β1 in synovial fluid aspirates of patients with temporomandibular disorders.J Oral Maxillofac Surg. 1999; 57: 922Abstract Full Text PDF PubMed Scopus (39) Google Scholar that might play a role in the pathogenesis of ID and OA in the TMJ. Furthermore, the role of individual cytokines in the inflammatory process is influenced by the actions of other cytokines and can be regulated in an autocrine or paracrine fashion by a number of cytokines.1Kaneyama K. Segami N. Nishimura M. et al.Importance of proinflammatory cytokines in synovial fluid from 121 joints with temporomandibular disorders.Br J Oral Maxillofac Surg. 2002; 40: 418Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar The authors are to be commended for their industrious work in this most challenging surgical discipline of oral and maxillofacial surgery.