Effect of a Benzylidene Derivative, Novel Antirheumatic Agent, on the Production of Tissue Inhibitor of Metalloproteinases.

Abstract

We investigated the effects of PAL (protocatechualdehyde), a metabolite of ACP (3,4-diacetoxy benzylidene diacetate) which is a candidate as a novel antirheumatic agent, on the production of a tissue inhibitor of metalloproteinases (TIMP) using a primary chondrocyte culture from bovine nasal septum cartilage. The addition of human recombinant interleukin-1 alpha (hrIL-1 alpha) induced proteoglycan (PG) depletion from a chondrocyte matrix. PAL significantly reduced the induction of PG depletion. HrIL-1 alpha increased the casein-degrading activity, matrix metalloproteinase (MMP) activity, and the level of TIMP secretion in the culture media. PAL significantly reduced the casein-degrading activity and further increased TIMP secretion under hrIL-1 alpha stimulation. Phorbol myristate acetate (PMA) also increased the level of TIMP secretion, and staurosporine, a specific inhibitor of protein kinase C (PKC), reduced the TIMP secretion to the control level under hrIL-1 alpha or PMA stimulation. Furthermore, PAL showed a significant increase following treatment with a low concentration of PMA which alone did not increase TIMP production. These findings suggest that the activation of the PKC pathway plays an important role in TIMP production and that PAL increases the level of TIMP production through an additive or synergistic effect with the activation of the PKC pathway. In conclusion, these findings demonstrate that the inhibition of the MMP activity and the increase of TIMP production by PAL contribute to the inhibition of PG depletion in a primary chondrocyte culture from bovine nasal septum cartilage.