Characterization of bone resorbing activity in gingival crevicular fluid from patients with periodontitis

Background: In attempts to elucidate factors stimulating bone resorption in patients with different inflammatory diseases in the vicinity of the skele ton, e.g., peridontal disease and rheumatoid arthritis, we are investigatin g the presence of bone-resorbing activity in a variety of inflammatory exud ates. The aim of the present study was to characterize the bone-resorbing a ctivity present in patients with periodontitis. Methods: Bone-resorbing activity was assessed in gingival crevicular fluids (GCFs) collected from patients with periodontitis and from patients with n o signs of gingivitis. Bone-resorbing activity was evaluated by analyzing t he capacity of GCFs to stimulate the release of minerals and the breakdown of bone matrix proteins in cultured neonatal mouse calvariae. The concentra tions of IL-1 alpha, IL-1 beta and PGE(2) were determined with ELISA and RI A techniques, respectively. Results: GCF eluates from 24 different healthy sites caused a 1.23+/-0.05 f old stimulation of Ca-45 release, whereas GCF eluates from 45 different dis eased (periodontitis) sites caused a 2.46+/-0.10 fold stimulation. The effe ct on Ca-45 release was time- and concentration-dependent, inhibited by 3 d ifferent osteoclast inhibitors and associated with enhanced release of H-3 from [H-3]-proline-labelled bones. The activity in GCF causing enhanced Ca- 45 release was unaffected, or in some samples partially reduced, by ultrafi ltration using a filter with a molecular weight cut-off of 3000 Daltons. Th e bone-resorbing activity was temperature sensitive (+90 degrees C, 10 min) . The concentrations of prostaglandin E-2 (PGE(2)) in the diluted GCF eluat es, used in the bone resorption bioassay, were too low to be responsible fo r the release of Ca-45. Antisera specifically neutralizing human IL-1 alpha inhibited the stimulatory effect of GCF pooled from several diseased sites . The specific, recombinant human IL-1 receptor antagonist completely inhib ited the effect of pooled GCFs. GCF eluates from diseased sites contained h uman IL-1 alpha and IL-1 beta at concentrations of 1838 +/- 294 pg/ml and 5 12 +/- 91 pg/ml, respectively. Conclusions: These data show that GCF contains activity(ies) stimulating os teoclastic bone resorption in vitro. The factor primarily responsible for t his activity seems to be IL-1 alpha, but IL-1 alpha is not the sole activat or of bone resorption in GCF.