2014 Volume 57 Issue 1 Pages 1-8
Purpose: Dental pulp is involved in nutrient supply to the dentin and the maintenance of homeostasis, and plays a major role in reparative dentin formation. Dental pulp inflammation associated with the progression of dental caries facilitates the production of inflammatory cytokines such as interleukin-1β (IL-1β) and enzymes such as matrix metalloproteinases (MMPs) in the pulp tissue, resulting in tissue destruction. Elucidating the pathogenesis of pulpitis is important for dental pulp preservation. Thus, we investigated MMP-3 production by inflammatory cytokine IL-1β stimulation and extracellular signal-regulated kinase 1/2 (ERK1/2), an intracellular signal transducer, in human dental pulp fibroblast-like cells (HPFs).
Methods: Under approval No. 070716 of the Ethics Committee of Osaka Dental University, HPFs from teeth extracted during orthodontic treatment were primarily cultured for three to ten generations to be used in the present study. HPFs were cultured in serum-free α-MEM, followed by the addition of IL-1β (0, 1, 2, 5, and 10 ng/ml) and an MEK inhibitor (U0126). MMP-3 production and ERK1/2 phosphorylation after the stimulation were examined by Western blotting using their detection antibodies. The supernatant was subjected to electrophoresis by SDS-PAGE using 1 mg/ml gelatin to be examined by gelatin zymography.
Results: MMP-3 production in HPFs was enhanced by IL-1β stimulation. ERK1/2 phosphorylation was enhanced in an IL-1β concentration-dependent manner. Furthermore, the MEK1/2 inhibitor U0126 inhibited the ERK1/2 phosphorylation and MMP-3 production enhanced by IL-1β stimulation.
Conclusion: The results of this experiment suggest that the MEK1/2 and ERK1/2 pathways are involved in MMP-3 production enhanced by IL-1β stimulation in HPFs.
