MATRIX METALLOPROTEINASE-3 (MMP-3), or stromelysin-1, is an enzyme responsible for the degradation of a wide range of extracellular matrix proteins. Increases in MMP-3 activity have been found in several chronic inflammatory diseases, and this increased activity is thought to be mediated by interleukin-1 beta (IL-1 beta). Because IL-1 beta has been strongly associated with inflammatory periodontal disease, the purpose of this in vitro study was to investigate the role of IL-1 beta on the regulation of MMP-3 levels in cells derived from the human periodontal ligament (PDL). Human PDL cell cultures were treated with IL-1 beta at varying concentrations (0.01-1.0 ng/ml) for 24 hour prior to analysis at either transcript or protein levels. Following the isolation of total RNA, the relative levels of MMP-3 mRNA were determined using reverse transcription-polymerase chain reaction (RT-PCR) with 32P-end-labeled primers. Immunocytochemical detection of MMP-3 protein was performed using polyclonal antibodies to human MMP-3. The results of RT-PCR analysis demonstrated a concentration-dependent increase in MMP-3 mRNA expression, with IL-1 beta treatments of 0.1 and 1.0 ng/ml significantly (P < 0.01) increased over those cells not treated with IL-1 beta. This increase in mRNA expression was paralleled by significant (P < 0.001) changes at the protein level, with an average of 27.6% of the cells stained positive for MMP-3 following IL-1 beta treatment (1.0 ng/ml), compared with control cells showing no positive staining for MMP-3. In conclusion, the results of this study demonstrate that IL-1 beta upregulates MMP-3 in human PDL cells on both an mRNA and a protein level. These findings suggest possibly important roles for IL-1 beta and MMP-3 in both normal turnover and maintenance of the PDL and in the connective tissue degradation associated with periodontal disease.

This study demonstrates an inhibitory effect of tiludronate on the activity of both MMP-1 and MMP-3. These effects appear to occur without altering either mRNA or protein levels for these enzymes, supporting a possible mechanism of action that involves the ability of bisphosphonates to chelate cations from the MMPs. Furthermore, these results support the continued investigation of these drugs as potential therapeutic agents in periodontal disease.

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Previous studies have shown that costochondral cartilage cell cultures produce extracellular matrix vesicles which contain metalloproteinase activity. In the present study, we examined whether two matrix metalloproteinases (MMPs) known to be present in cartilage, stromelysin-1 and 72 kDa gelatinase, are expressed by fourth passage resting zone and growth zone costochondral chondrocytes and whether they are specifically incorporated into matrix vesicles produced by the cells. We also examined whether the cells synthesize tissue inhibitor of metalloproteinase-1 and -2 (TIMP-1 and TIMP-2). Oligonucleotide primers for stromelysin-1, 72 kDa gelatinase, tissue inhibitor of metalloproteinases-1 and -2 (TIMP-1 and TIMP-2), and GAPDH were synthesized and optimized for use in the reverse transcription-polymerase chain reaction (RT-PCR). It was found that both resting zone and growth zone chondrocytes produced mRNA for both MMPs and the two TIMPs. Further, immunostaining of cell layers with antibodies to 72 kDa gelatinase and stromelysin-1 showed that both cell types produced these MMPs in culture. Substrate gel electrophoresis and Western analysis were used to characterize MMP activity in matrix vesicles, media vesicles, or plasma membranes as well as in conditioned media produced by the chondrocyte cultures. It was found that matrix vesicles but not plasma membranes or media vesicles were selectively enriched in stromelysin-1. Also, 72 kDa gelatinase was found in matrix vesicles, but to a lesser extent than seen in media vesicles. The relative activity of each enzyme detected was cell maturation-dependent. No MMP activity was detected in conditioned media produced by either cell type. The results of this study show that MMPs are expressed by resting zone and growth zone chondrocytes in culture and differentially distributed among three different membrane compartments. This suggests that, in addition to the well-known activators and inhibitors of MMP activity in the matrix, differential membrane distribution may enable more precise control over the site, rate, and extent of matrix degradation by the cell.