Prolonged matrix metalloproteinase-3 high expression after cyclic compressive load on human synovial cells in three-dimensional cultured tissue

Excessive mechanical stress is thought to be a factor in the development of joint disorders through the expression of matrix metalloproteinases (MMPs) and related cytokines. Although studies revealed that mechanical stress on the synovium induces MMP expression, it is still not known which MMPs prolonged high level expression. The authors focused on MMP-3, which is one of the major factors in joint disorders such as rheumatism and temporomandibular joint disorders. They examined mRNA and protein levels of MMP-3, other MMPs and related cytokines after loading stress. Human synovial cells were seeded onto a collagen scaffold and different magnitudes of cyclic compressive load were applied for 1 h. Time-dependent mRNA and protein levels for catabolic genes were examined after loading. mRNA expressions of MMP-1, MMP-3, MMP-9, IL-6, IL-8 and IL-1β increased after excessive compression. In particular, only mRNA of MMP-3 was up-regulated and maintained at a high level for 24 h after excessive loading. The concentrations of MMP-3, IL-6 and IL-8 in culture media after loading increased with excessive compression. These results may account for the pathomechanism of MMP-3 induced by cyclic load on synovial cells in joint disorders.