Effects of bisphosphonate on matrix metalloproteinase enzymes in human periodontal ligament cells

Background: The host response is a critical component in the pathogenesis o f periodontitis. In fact, the clinical benefits associated with regulating the host response have been demonstrated in studies using several different classes of drugs. Biophosphates are one host-modulating class of drugs tha t has demonstrated this ability These drugs are clinically effective at red ucing bone resorption and have shown the ability to inhibit host degradativ e enzymes, specifically the matrix metalloproteinases (MMPs). Therefore, th e purpose of this study was to investigate the regulatory effects of a bisp hosphonate, tiludronate, on MMP levels and activity in human periodontal ce lls. Methods: MMP-1 and MMP-3 were assessed in cultured human periodontal ligame nt cells treated with a bisphosphonate, tiludronate. Reverse transcription- polymerase chain reaction was used to identify mRNA levels for both enzymes , and also for tissue inhibitors (TIMP-1). Enzyme immunoassay (EIA) and imm unocytochemistry were used to assess MMP proteins in these cell cultures. E nzyme activity was assessed using FITC-conjugated substrates and quantitate d using spectrophotofluorometry. Results: Tiludronate significantly inhibited both MMP-1 and MMP-3 activity in a concentration-dependent manner. A maximal reduction in activity of 35% was achieved for each of the enzymes at a 10(-4) M concentration. Tiludron ate did not have a significant effect on the mRNA levels for MMP-1, MMP-3, or TIMP-1. Similarly, there were no effects noted for either MMP-1 or MMP-3 on the protein level. Conclusions: This study demonstrates an inhibitory effect of tiludronate on the activity of both MMP-1 and MMP-3. These effects appear to occur withou t altering either mRNA or protein levels for these enzymes, supporting a po ssible mechanism of action that involves the ability of bisphosphonates to chelate cations from the MMPs. Furthermore, these results support the conti nued investigation of these drugs as potential therapeutic agents in period ontal disease.