title: [Inhibitory effects of Porphyromonas endodontalis lipopolysaccharides on proliferation and differentiation of mouse osteoblast].
abstract: OBJECTIVE
  To observe the effect of lipopolysaccharides (LPS) extracted from Porphyromonas endodontalis (Pe) on osteoblast cell proliferation and the activity of alkaline phosphatase (ALP) and interleukin (IL)-6 secretion and to investigate the role of Pe-LPS in osteoblast proliferation and differentiation.
  
  
  METHODS
  MC3T3-E1 cells were treated with different concentrations of Pe-LPS (10, 25, 50 mg/L) respectively. The relative growth rate (RGR) was detected by methyl thiazolyl tetrazolium (MTT) at different time point (12, 24, 48, 72 h). MC3T3-E1 cells were also stimulated with 10, 25 or 50 mg/L Pe-LPS for 6, 12, 24 and 48 h. The activity of ALP was detected by enzyme kinetics assay and the secretion of IL-6 was detected by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  After the stimulation with 25 or 50 mg/L Pe-LPS for 72 h, the RGR of MC3T3-E1 cells descend to 87.46% and 71.12%. The ALP activities of MC3T3-E1 cells were inhibited obviously (P < 0.05) after the stimulation of different concentrations (10, 25, 50 mg/L) Pe-LPS for more than 24 hours. ELISA result showed that IL-6 increased to 32.21 ng/L treated with the 25 mg/L Pe-LPS for 6 h, 25 mg/L Pe-LPS gradually increased the expression of IL-6 from the ELISA results.
  
  
  CONCLUSIONS
  Pe-LPS can induce the secretion of IL-6 in MC3T3-E1 and decrease the ALP activities of MC3T3-E1, the differentiation of osteoblasts was inhibited. with the long-time toxicity action of Pe-LPS, the proliferation rate of MC3T3-E1 also markedly decreased.
authors.affiliation: Department of Endodontics, China Medical University, Shenyang 110002, China.
authors.forename: Ren
authors.initials: R
authors.lastname: Li
authors.forename: Li-hong
authors.initials: LH
authors.lastname: Qiu
authors.forename: Di
authors.initials: D
authors.lastname: Yang
authors.forename: Ming
authors.initials: M
authors.lastname: Xue
authors.forename: Ming
authors.initials: M
authors.lastname: Zhong
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015850:Interleukin-6 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D045202:Porphyromonas endodontalis / Q000737:chemistry*
chemical_list: D015850:Interleukin-6; D008070:Lipopolysaccharides; D000469:Alkaline Phosphatase