title: An acute injection of Porphyromonas gingivalis lipopolysaccharide modulates the OPG/RANKL system and interleukin-6 in an ovariectomized mouse model.
abstract: OBJECTIVE
  In the present study, we attempted to develop a simulated model to explore the causal effects of periodontal pathogens on skeletal homeostasis in postmenopausal osteoporosis.
  
  
  METHODS
  Fifty-three female adult ICR mice were randomly assigned to an experimental group (ovariectomized) or a control group. A single injection of Porphyromonas gingivalis lipopolysaccharide (P. gingivalis-LPS, ATCC 33277) or Escherichia coli lipopolysaccharide (E. coli-LPS) was administered intraperitoneally 4 weeks after an ovariectomy. Concentrations of interleukin-6 (IL-6), osteoprotegerin (OPG), and the receptor activator of nuclear factor-kappaB ligand (RANKL) in serum were subsequently analyzed using an enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  Under stimulation with P. gingivalis-LPS or E. coli-LPS, the concentration of OPG rose in both groups. The serum level of RANKL showed a decreasing trend 24 h after the injection in both groups. After injection of P. gingivalis-LPS in both the experimental and control animals, the OPG : RANKL ratio increased 24 h after the booster (22.26-620.99, P < 0.05). The serum level of IL-6 in the experimental group significantly increased 1-6 h after administration of E. coli-LPS and 1-3 h after administration of P. gingivalis-LPS (P < 0.05).
  
  
  CONCLUSIONS
  A single booster injection of P. gingivalis-LPS induced short-term changes in OPG, RANKL, and IL-6 serum levels in this ovariectomized mouse model.
authors.affiliation: Periodontal Clinic, Dental Department, Taipei Medical University Hospital, Taipei, Taiwan.
authors.forename: H-K
authors.initials: HK
authors.lastname: Lu
authors.forename: K-C
authors.initials: KC
authors.lastname: Yeh
authors.forename: M-F
authors.initials: MF
authors.lastname: Wu
authors.forename: C-L
authors.initials: CL
authors.lastname: Li
authors.forename: C-C
authors.initials: CC
authors.lastname: Tseng
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004926:Escherichia coli; D005260:Female; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D007274:Injections, Intraperitoneal; D015850:Interleukin-6 / Q000097:blood*; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D008813:Mice, Inbred ICR; D010024:Osteoporosis / Q000503:physiopathology; D053244:Osteoprotegerin / Q000097:blood* / Q000187:drug effects; D010052:Ovariectomy; D016966:Porphyromonas gingivalis; D053245:RANK Ligand / Q000097:blood* / Q000187:drug effects; D011897:Random Allocation; D013997:Time Factors
chemical_list: D015850:Interleukin-6; D008070:Lipopolysaccharides; D053244:Osteoprotegerin; D053245:RANK Ligand