Effect of interleukin-1β on gene expressions and functions of fibroblastic cells derived from human periodontal ligament

The present study shows the effect of interleukin‐1β (IL‐1β) on some gene expressions and functions of fibroblastic cells (HPLF) derived from human periodontal ligament. HPLF were used at passages number 5 to 10. IL‐1β increased DNA synthesis in both a dose‐ and an incubation time‐dependent manner. IL‐1β in combination with tumor‐necrosis factor α or transforming growth factor β synergistically stimulated the DNA synthesis in the cells. Since many studies have shown that the c‐myc oncogene is involved in cell proliferation and differentiation, the effect of IL‐1β on c‐myc messenger RNA (mRNA) level in HPLF was examined. IL‐1β induced a marked c‐myc mRNA level in the cells at 90 minutes after initiation of the cytokine treatment. On the other hand, IL‐1β significantly inhibited alkaline phosphatase (ALP) activity of the cells in a dose‐dependent manner. Also an inhibitory effect was observed on the liver/bone/kidney ALP mRNA level of the cells, and this inhibition by IL‐1β was dose‐ and incubation time‐dependent. These results suggest that IL‐1β is a regulatory cytokine involved in the regeneration of the human periodontal ligament.