title: PPARγ inhibits inflammation and RANKL expression in epoxy resin-based sealer-induced osteoblast precursor cells E1 cells.
abstract: OBJECTIVE
  The AH26 of epoxy resin-based sealer is used widely owing to its excellent physical characteristics but it induces oxidative stress and cytotoxicity at the periapical tissues. AH26 exhibited cytotoxicity towards MC-3T3-E1 cells, which resulted in mitochondria-mediated apoptosis. Peroxisome proliferator-activated receptor (PPARγ) has an anti-inflammatory effect in several tissue and cells, but its action of AH26-related inflammation is not completely understood. The aim of this study is to investigate the anti-inflammatory and anti-osteoclastic mechanisms of PPARγ in AH26-induced MC-3T3 E1 cells.
  
  
  METHODS
  AH26 was prepared according to the manufacturer's instructions. The 1-day extraction sample, which was diluted by 30%, was tested in this experiment. Recombinant deficiency adenoviral PPARγ (Ad/PPARγ) was used to examine PPARγ over-expression in MC-3T3 E1 cells. AH26-induced reactive oxygen species (ROS) formation was analysed using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) with fluorescence-activated cell sorting (FACS), and the expression of receptor activator of nuclear factor-κB ligand (RANKL) and inflammatory molecules was determined by immunoblotting. The anti-inflammatory and anti-osteoclastic mechanisms of the PPARγ-involved signal pathway was examined by immunoblotting.
  
  
  RESULTS
  The AH26 elutes induced inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), RANKL expression and ROS formation. In addition, the AH26 elutes suppressed the expression of PPARγ. However, the recovery of PPARγ expression with Ad/PPARγ resulted in the inhibition of iNOS, COX-2, RANKL and ROS formation despite the AH26 treatment in MC-3T3 E1 cells. The mechanism of PPARγ was confirmed by the blocking of nuclear factor kappa B (NF-κB) translocation to the nucleus after the suppression of ERK1/2, SAPK/JNK and AP-1 in AH26-induced MC-3T3 E1 cells.
  
  
  CONCLUSIONS
  From this result, PPARγ acts to inhibit bone destruction in AH26-induced bone cells. Therefore, the anti-inflammatory and anti-osteoclastic character of PPARγ might be applicable for healing periapical lesions more rapidly or reducing the induction of cellular inflammation caused by some endodontic sealers.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Chonbuk National University, Jeonju, Republic of Korea.
authors.forename: Tae-Gun
authors.initials: TG
authors.lastname: Kim
authors.forename: Young-Hee
authors.initials: YH
authors.lastname: Lee
authors.forename: Govinda
authors.initials: G
authors.lastname: Bhattari
authors.forename: Nan-Hee
authors.initials: NH
authors.lastname: Lee
authors.forename: Kwang-Won
authors.initials: KW
authors.lastname: Lee
authors.forename: Ho-Keun
authors.initials: HK
authors.lastname: Yi
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Yu
mesh_terms: D016475:3T3 Cells; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001729:Bismuth / Q000494:pharmacology*; D015153:Blotting, Western; D002469:Cell Separation; D051546:Cyclooxygenase 2 / Q000187:drug effects; D004853:Epoxy Resins / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects; D005434:Flow Cytometry; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005822:Genetic Vectors / Q000235:genetics; D018836:Inflammation Mediators / Q000378:metabolism; D048670:MAP Kinase Kinase 4 / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D016328:NF-kappa B / Q000187:drug effects; D052247:Nitric Oxide Synthase Type II / Q000187:drug effects; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D010010:Osteoclasts / Q000187:drug effects*; D047495:PPAR gamma / Q000032:analysis / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D053245:RANK Ligand / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000032:analysis; D012387:Root Canal Filling Materials / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D012834:Silver / Q000494:pharmacology*; D014025:Titanium / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000187:drug effects; D014162:Transfection
chemical_list: D000893:Anti-Inflammatory Agents; D004853:Epoxy Resins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D018836:Inflammation Mediators; D016328:NF-kappa B; D047495:PPAR gamma; D053245:RANK Ligand; D017382:Reactive Oxygen Species; D012387:Root Canal Filling Materials; C505689:Tnfsf11 protein, mouse; D018808:Transcription Factor AP-1; C029569:diacetyldichlorofluorescein; D012834:Silver; C028044:epoxy resin AH-26; D014025:Titanium; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D048670:MAP Kinase Kinase 4; D001729:Bismuth