title: Identification of the osteoprotegerin/receptor activator of nuclear factor-kappa B ligand system in gingival crevicular fluid and tissue of patients with chronic periodontitis.
abstract: OBJECTIVE
  Recent findings have suggested that osteoclastogenesis is directly regulated by receptor activator of nuclear factor-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG). However, no studies have described interactions of OPG/RANKL and the gp130 cytokine family in periodontal disease. This study aimed to identify and quantify OPG/RANKL in the gingival crevicular fluid (GCF) and connective tissue of patients with periodontitis, and to clarify possible correlations with disease severity and interleukin-6 (IL-6) cytokines.
  
  
  METHODS
  Ninety-five sites in 20 patients with generalized chronic periodontitis were divided into four groups by site based on probing depth (PD) and bleeding on probing (BOP). In periodontitis patients, GCF was obtained using sterile paper strips from clinically healthy sites (PD <or= 3 mm without BOP, n = 12 in periodontitis subjects), mildly diseased sites (PD <or= 3 mm with BOP, n = 23), moderately diseased sites (PD <or= 4-6 mm with BOP, n = 33) and severely diseased sites (PD > 6 mm with BOP, n = 27). Fourteen clinically healthy sites from four periodontally healthy individuals were used as the control group. The levels of OPG, RANKL and two gp130 cytokines - IL-6 and oncostatin M (OSM) - in the GCF were determined by an enzyme-linked immunosorbent assay (ELISA) and are expressed as total amounts (pg/site). Immunohistochemical localization of OPG- and RANKL-positive cells was also performed on gingival connective tissues harvested from patients with periodontitis (inflammatory group, n = 8 biopsies) and from non-diseased individuals (healthy group, n = 8 biopsies).
  
  
  RESULTS
  GCF RANKL, but not OPG, was elevated in diseased sites of patients with periodontitis. However, the expressions of OPG and RANKL showed no correlation with disease severity (r = 0.174 and 0.056, respectively), but the content of RANKL in the GCF was significantly positively correlated with those of IL-6 (r = 0.207) and OSM (r = 0.231) (p < 0.01). Immunohistochemical staining showed that RANKL-positive cells were significantly distributed in the inflammatory connective tissue zone of diseased gingiva, compared with those of samples from non-diseased persons (p < 0.01). However, few OPG-positive cells were found in connective tissue zones of either the diseased gingiva or healthy biopsies.
  
  
  CONCLUSIONS
  These findings imply that in this cross-sectional study of GCF, RANKL, IL-6 and OSM were all prominent in periodontitis sites, whereas OPG was inconsistently found in a few samples of diseased sites but was undetectable in any of the control sites. The results also imply that the expression of RANKL was positively correlated with IL-6 and OSM in the GCF.
authors.affiliation: College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: H-K
authors.initials: HK
authors.lastname: Lu
authors.forename: Y-L
authors.initials: YL
authors.lastname: Chen
authors.forename: H-C
authors.initials: HC
authors.lastname: Chang
authors.forename: C-L
authors.initials: CL
authors.lastname: Li
authors.forename: M Y-P
authors.initials: MY
authors.lastname: Kuo
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism*; D016022:Case-Control Studies; D002908:Chronic Disease; D016207:Cytokines / Q000032:analysis / Q000378:metabolism; D005260:Female; D005881:Gingiva / Q000378:metabolism; D005883:Gingival Crevicular Fluid / Q000378:metabolism; D006023:Glycoproteins / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000032:analysis / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis / Q000378:metabolism*; D008875:Middle Aged; D053683:Oncostatin M; D053244:Osteoprotegerin; D010512:Periodontal Index; D010518:Periodontitis / Q000378:metabolism*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis / Q000378:metabolism*; D018709:Statistics, Nonparametric
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; D006023:Glycoproteins; D015850:Interleukin-6; D008562:Membrane Glycoproteins; C508351:OSM protein, human; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; D053683:Oncostatin M