Journal of Dental Research, Vol 70, 27-33, Copyright © 1991 by International & American Associations for Dental Research Online Journals
Involvement of PGE synthesis in the effect of intermittent pressure and interleukin-1 beta on bone resorption
S. Saito, P. Ngan, T. Rosol, M. Saito, H. Shimizu, N. Shinjo, J. Shanfeld and Z. Davidovitch
Department of Orthodontics, Showa University, Tokyo, Japan.
Human periodontal ligament (PDL) fibroblasts, cultured from extracted
healthy premolars, and a cloned osteogenic cell line (MC3T3-E1) were used
in this study to determine the effect of intermittent pressure on bone
resorption. Cells (1 x 10(5] were incubated with BGJb medium in the
presence or absence of the following factors: intermittent negative (-30
g/cm2) or positive (30 g/cm2) hydrostatic pressure and interleukin-1 beta
(IL-1 beta, 1 ng/mL), for 24 h. Conditioned media (CM) generated from
cultures of either cell types were used for prostaglandin E (PGE) assay,
bone resorption assay, and assessment of osteoclast (OC)-like cell
formation. Unstimulated PDL fibroblasts or MC3T3-E1 cells produced
measurable amounts of PGE and bone-resorbing activity as measured by 45Ca
released from mouse calvaria and OC-like cells. IL-1 beta-treated cells
showed significantly elevated levels of PGE, bone resorption, and OC-like
cell formation, as compared with unstimulated cells. Intermittent positive
pressure (IPP) alone stimulated PGE production, but the resultant CM did
not stimulate bone resorption or OC-like cell formation when IPP was
applied to either cell type. The application of IPP, together with IL-1
beta in CM, caused a slight increase in the number of alpha-like cells, as
compared with that of IL-1 beta-treated CM in both cell types. On the other
hand, direct application of IPP on mouse bone-marrow cultures significantly
increased the number of OC-like cells. This effect was additive in
combination with either CM from unstimulated cells or exogenous addition of
PGE2.(ABSTRACT TRUNCATED AT 250 WORDS)
