Role of interleukin-1 in induction of matrix metalloproteinases synthesized by rat temporomandibular joint chondrocytes and disc cells

Abstract

To identify cartilage-degrading enzymes and cell types that can be specifically induced by interleukin-1 (IL-1)α, we studied matrix metalloproteinase (MMP) activities of cultured rat temporomandibular joint (TMJ) chondrocytes and disc cells. The cells were isolated from TMJs pre-injected with normal physiological saline (CR) or recombinant human IL-1α (AR). MMP activities in the conditioned media were assayed by gelatin enzymography, and they were identified by Western blot analyses. MMP mRNAs in these cells were also detected by RT-PCR. IL-1α significantly induced an increase of active MMP9 as well as pro- and active MMP3, but had no effect on the MMP2 activity in both types of cells. MMP3 and MMP9 mRNAs were also inducible in these cells by IL-1α stimulation. Furthermore, disc cells were more susceptible to IL-1α than chondrocytes. AR cells spontaneously produced the same MMPs in vitro as the CR cells synthesized under IL-1α stimulation. The results indicate that MMP9 and MMP3 were predominantly produced by disc cells, and these may be considered to play a pivotal role in ECM degradation during pathological conditions of the TMJ, such as IL-1-induced TMJ arthritis. Copyright © Eur J Oral Sci 2001.