Dental caries often causes pulp inflammation once it reaches the dentine. In deep caries, there are many kinds of bacterial components, such as lipopolysaccharide (LPS), that induce the production of proinflammatory mediators, including tumor necrosis factor (TNF)-alpha. Inflammation in dental pulp tissue is associated with tissue degradation, and matrix metalloproteinases (MMPs) are believed to participate in this destruction. In the present study, we examined whether TNF-alpha and LPS affect the production of MMP-1 and MMP-3 in human dental pulp cells (HDPCs) of deciduous teeth utilizing RT-PCR and ELISA analyses. Exposure of HDPCs to TNF-alpha at 10 ng/ml for 6 h significantly increased the gene expression of MMP-1 and MMP-3. MMP-1 gene expression was slightly affected by exposure to LPS, while MMP-3 gene expression was significantly elevated by LPS at 0.1, 1 and 5 mu g/ml. TNF-alpha at 10 ng/ml and LPS at 1 and 5 mu g/ml potentiated the protein production of MMP-3, but not MMP-1, in HDPCs. The results of this study suggests that the mechanisms by which TNF-alpha and LPS induce MMP-3 expression may be important links in the pathogenesis of inflammatory diseases and reparative dentin formation in HDPCs of deciduous teeth.
