title: [Mechanism of TNF-α in bone defect of chronic apical periodontitis].
abstract: OBJECTIVE
  To investigate the effect of lipopolysaccharides(LPS) extracted from Porphyromonas endodontalis(P.e) on the expression of tumor necrosis factor-α(TNF-α) mRNA in MC3T3-E1 cells and the role of NF-κB signaling on the expression of macrophage colony stimulating factor (M-CSF) induced by TNF-α in MC3T3-El cells． METHODS: MC3T3-E1 cells were treated with different concentrations of P.e-LPS(0-50 mg/L) and 10 mg/L P.e-LPS for different time (0-24 h). The expression of TNF-α mRNA was detected by reverse transcription polymerase chain reaction(RT-PCR). MC3T3-E1 cells were treated with different concentrations of TNF-α(0-10 ng/L) for 6 h. The expression of M-CSF mRNA and protein was detected by RT-PCR and enzyme-linked immunoadsordent assay(ELISA).The expression of M-CSF protein was also detected in 10 ng/L TNF-α treated MC3T3-E1 cells after pretreated with BAY 11-7082 for 1 h, a special NF-κB inhibitor . Statistical analysis was performed using Multi-way ANOVA and Dunnett t test with SPSS 13.0 software package.
  
  
  RESULTS
  The level of TNF-α mRNA increased significantly after treatment with different concentrations of P.e-LPS(0-50 mg/L)，which indicated that P.e-LPS induced osteoblasts to express TNF-α mRNA in dose dependent manners. Maximal induction of TNF-α mRNA expression was seen in the MC3T3-E1 cells treated with 10 mg/L P.e-LPS for 6 h. After 6 h, the expression of TNF-α mRNA decreased gradually .The expression of M-CSF mRNA and protein was increased in a does- dependent manner by different concentrations of TNF-α treatment（0-10 ng/L）. The expression of M-CSF protein increased from (37±2) ng/L(control group) to (301±8) ng/L(10 ng/L group).The protein of M-CSF decreased significantly after pretreatment with 10 μmol/L BAY 11-7082 for 1 h, and the expression of M-CSF proteins was reduced from (253±14) ng/L to (154±2) ng/L .BAY group had no significant difference from the control group.
  
  
  CONCLUSIONS
  The expression of TNF-α mRNA was increased by P. endodontalis LPS treatment in osteoblast. TNF-α may induce the expression of M-CSF in MC3T3-E1 cells through the signaling of NF-κB. It suggests that TNF-α affect osteoblasts through autocrine way for bone destruction in chronic apical periodontitis induced by P.e-LPS.
authors.affiliation: Department of Endodontics,School of Stomatology,China Medical University; Lab of Endodontic,Liaoning Institute of Dental Research;Liaoning Provincial Research Center of Translational Oral Medicine. Shenyang 110002, China. E-mail:yuyaqiong1987@126.com.
authors.forename: Ya-Qiong
authors.initials: YQ
authors.lastname: Yu
authors.forename: Liu
authors.initials: L
authors.lastname: Qu
authors.forename: Li-Hong
authors.initials: LH
authors.lastname: Qiu
authors.forename: Jia-Jie
authors.initials: JJ
authors.lastname: Guo
authors.forename: Nan
authors.initials: N
authors.lastname: Ma
authors.forename: Li
authors.initials: L
authors.lastname: Zhu
mesh_terms: D000818:Animals; D001842:Bone and Bones; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009570:Nitriles; D010006:Osteoblasts; D010485:Periapical Periodontitis; D045202:Porphyromonas endodontalis; D012333:RNA, Messenger; D015398:Signal Transduction; D013450:Sulfones; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009570:Nitriles; C498143:RELA protein, human; D012333:RNA, Messenger; D013450:Sulfones; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha