|Budget Amount *help
¥2,800,000 (Direct Cost : ¥2,800,000)
Fiscal Year 1999 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1998 : ¥1,500,000 (Direct Cost : ¥1,500,000)
The present study investigated the influence of hydrostatic pressure (HP) on the cytokine expression by an osteoblast cell line, MG-63. The cells were cultured in dishes until they reach a confluent level, and then exposed to HP of 1, 10, or 50 Ma for 2 h in an apparatus that can add pressure under sterile conditions. Twelve and 24 h after giving the exposure, interleukin (IL)-1α, IL-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, interferon (IFN)- α and IFN-γ levels in culture supernatants were measured with ELISA method. Total RNA was extracted 4 h after the exposure with the acid guanidinium thiocyanate-phenolchloroform method, and IL-8 mRNA expression was confirmed by Northern blot hybridization using a digoxigenin-labeled probe. The same procedure was repeated for the human fibroblast cell line TIG-3, as the control.
After the exposure to 1, 10 or 50 MPa of HP, IL-1α, IL-1β, IL-6, TNF-α, IFN-α and IFN-γ levels in MG-63 culture were lower than the minimum detectable level (20pg/ml). However, 12 and 24 h after the exposure to 50 MPa, IL-8 levels increased to 3 times the normal levels, and the expression of IL-8 mRNA also increased. In the control TIG-3 cells, levels of all cytokines examined after HP exposure were lower than the minimum detectable level.
These findings indicate that excessive mechanical stress can induce IL-8 production in osteoblasts. Mechanical factor may induced inflammatory reaction in bone tissues that then could result in bone destruction.