Co-expression of interleukin-1β and tumor necrosis factor α in synovial tissues and synovial fluids of temporomandibular joint with internal derangement:: comparision with histological grading of synovial inflammation

Background: It has been clarified that interleukin-1 (IL-1)beta and tumor necrosis factor (TNF)alpha play an important role in pathogenesis of various joint disease. The purpose of this study was to investigate the cellular source of IL-1beta and TNFalpha in temporomandibular joint (TMJ), and to analyze the relation between the expression of these cytokines and the intensity of TMJ synovial inflammation. Methods: We examined 33 synovial biopsy specimens from patients with internal derangement of the TMJ by an immunohistochemical technique using specific antibodies to IL-1beta and TNFalpha. We also studied 20 synovial fluids from the patients by enzyme-linked immunosorbent assay method. These data are compared with histological grading of synovial inflammation by Gynther's system. Results: Both IL-1beta and TNFalpha were predominantly localized in the synovial lining cell layer and the blood vessels of synovial biopsy specimens obtained from patients with TMJ internal derangement. A statistically significant correlation was found between the intensity of IL-1beta expression and that of TNFalpha. Additionally, the intensity of TNFalpha expression was statistically correlated with histological grading by Gynther's system. Conclusion: These results supported that IL-1beta and TNFalpha may be involved in the occurrence of TMJ internal derangement and that they coordinately play an role in pathogenesis of TMJ internal derangement.