The effect of five osteotropic factors on osteoprotegerin mRNA expression in gingival fibroblasts / 대한치주과학회지

ABSTRACT

PURPOSE: Osteoprotegerin (OPG) is a secreted glycoprotein and a member of the tumor necrosis factor (TNF) receptor family that inhibits bone resorption by suppressing osteoclastogenesis. Gingival fibroblasts (GF) play a role in periodontal disease progression, and the purpose of this experiment was to evaluate influence of osteotropic factors on the expression of osteoprotegerin mRNA in these cells. MATERIALS AND METHODS: In this experiment, the influence of osteoclastogenic factors, interleukin-1 beta (IL-1beta), TNF-alpha, prostanglandin E2 (PGE2). parathyroid hormone (PTH) and 1alpha, 25-dihydroxyvitamin D3 on the expression of osteoprotegerin mRNA in GF was studied by Northern blot hybridization. RESULTS: As expected, PGE2 tended to inhibit OPG levels and this was most prominent at 24 hours of culture with 10(-7)M of PGE2. TNF-alpha at 10ng/ml and also at 25ng/ml decreased OPG levels to almost 30% of the control at 24 hours. This contrasts with reports of increased OPG levels from osteoblast/stromal cells and gingival fibroblasts stimulated by TNF-alpha. Decrease of OPG levels with PGE2 and TNF-alphasuggests a pathway whereby these mediators exert their resorptive effects. However, OPG levels were increased almost 3-fold at 24 hours with IL-1beta(1 to 15ng/ml) and increased 1.4 fold with 24-hour treatment of 10(-7)M PTH. CONCLUSION: Increase of OPG levels suggests that these 'osteoclastogenic' factors act in more complex ways and may act to inhibit bone resorption in inflammatory periodontitis. This result supports the role of OPG as a negative feedback mechanism in osteoclastic activity.