Interferon-γhas been suggested as a cytokine of connective tissue stabilizer. In addition. It has also been demonstrated that this cytokine inhibited bone remodeling activities of the bone derived cells. In order to illuminate the effects of
this
cytokine in orthodontic force induced bone remodeling. It wasadmiistered to primary cultured periodontal ligament cells which have been known to have some osteoblast like characteristics.
Interferon-γslighlty decreased [3H] thymidine incorporation rate without a significant change in the total cellular DNA content up to 1000 U/ml, which meant these doses were not cytotoxic to the cell. Total protein synthesis was not influenced
by
various concentration of interferon-γwhether it was determined by the [3H]proline incorporation rate or by the Lowry smethod. The effect of interferon-γon the indivvidual protein was, however, differential, ie, it increased [3H]proline
incorporation
into the noncollagenous protein marginally, while it decreased [3H] proline incorporation into the collagen, so that in cause dose-dependent suppression of the relative collagen synthesis. On the contrary, the fibronectin synthesis determined by
the
ELISA was increased by 1000 U/ml of interferon-γ. The differential effects of the interferon-γon the collagen and fibronectin synthesis exhibited not only their protein level but also the steady state mRNA level. Interferon-γdecreased steady
state
level of α1(I) procollagen mRNAsignificantly, while showing no significant changes in the fibronectin mRNA level. In addition to this, it was also found that indomethacin did not affect on the interferon-γinduced collagen decrease in this cell,
which
meant prostaglandins were not involed in the process of interferon-γinduced collagen decrease.
So it can be concluded that the incubation of periodontal ligament cells with 1000 u/ml of interferon-γfor 24 hr showed differential effects on the type I collagen and fibronectin gene expression. The decrease in relative collagen synthesis in
the
protein level was related with decrease in the steady state level of mRNA, while the increase in the fibronection synthesis in the protein level was not correlated with the mRNA level.
KOREA J ORTHOD 1993 ; 23(2) : 229-248.
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