The Effect Of Interleukin-1β On MMP-2,MMP-9 Expression Of Human Pulp Cells In Vitro

Matrix metalloproteinases (MMPs) form an enzyme family capable of degrading extracellular matrix (ECM). They play an important role in normal tissue remodelling and growth, as well as in many destructive pathological conditions such as inflammation, tumour growth and metastasis. Dental pulp is a loose mesenchymal tissue characterized its particular location and almost entirely enclosed in a mineralized tissue. Degeneration of matrix proteins is thought to occur in pulpal inflammation and MMPs may play a key role in tissue degradation in inflamed dental pulp. MMP expression is regulated at the transcriptional level by many growth factors and cytokines, oncogenes and hormones.Objective: The purpose of this study was to investigate the effect of interleukin-1β(IL-1β) on the synthesis and secretion of MMPs (MMP-2,MMP-9) of human pulp cells in vitro.Methods: Human dental pulp cells were cultivated from pulp connective tissue explants digested with collagenase I. Cells between the fourth and eighth passages were used in this study. The immunohistochemical method was applied to investigate the expression of MMPs (MMP-2n MMP-9) in human dental pulp cells with or without IL-1β, and gelatin zymography to examine the production of MMPs by dental pulp cell in course of cultures ( 2 to 10 days). Results: Human dental pulp cells were successfully cultivated from tissue explants digested with collagenase I. The results of immunohistochemical method and gelatin zymography revealed that MMP-2 and MMP-9 were expressed in normal human dental pulp cells, and IL-1βcould increase this level significantly. MMPs were localized major in the plasma of dental pulp cell and lesser in extracellular matrix. Untreated pulp cells secreted MMP-2 which increase slightly over the culture period. Upon treated with IL-1β, the cells demonstrate elevated levels of synthesis and secretion of MMP-2. The level begin to increase on day 2 and persist throughout the entire culture period. But the increase of MMP-9 is insignificant.Conclusions: Taken together, these results suggest that human dental pulp cells can be cultivated preferably from tissue explants digested with collagenase I in vitro. MMP-2 probably is one of the major matrix-degrading MMPs in the dental pulp. IL-ip could have the potential to stimulate the production of elevated levels of MMPs in human pulp cells and thus result in the inflammation of dental pulp.