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-1 beta (IL-1 beta) 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-1 beta increased DNA synthesis in both a dose- and an incubation time-dependent manner. IL-1 beta in combination with tumor-necrosis factor alpha or transforming growth factor beta 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-1 beta on c-myc messenger RNA (mRNA) level in HPLF was examined. IL-1 beta induced a marked c-myc mRNA level in the cells at 90 minutes after initiation of the cytokine treatment. On the other hand, IL-1 beta 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-1 beta was dose- and incubation time-dependent. These results suggest that IL-1 beta is a regulatory cytokine involved in the regeneration of the human periodontal ligament.