title: Nicotine and lipopolysaccharide stimulate the production of MMPs and prostaglandin E2 by hypoxia-inducible factor-1α up-regulation in human periodontal ligament cells.
abstract: OBJECTIVE
  Although hypoxia-inducible factor 1α (HIF-1α) is up-regulated in the periodontal pockets of periodontitis patients, the expression and precise molecular mechanisms of HIF-1α remain unknown in human periodontal ligament cells (PDLCs). The aim of this study was to explore the effects, as well as the signaling pathway, of nicotine and lipopolysaccharide (LPS) on the expression of HIF-1α and on the production of its target genes, including cyclooxygenase-2 (COX-2)-derived prostaglandin E(2) (PGE(2) ), MMP-2 and MMP-9 in PDLCs.
  
  
  METHODS
  The expression of COX-2 and HIF-1α proteins was evaluated using western blotting. The production of PGE(2) and MMPs was evaluated using enzyme immunoassays and zymography, respectively.
  
  
  RESULTS
  LPS and nicotine synergistically induced the production of PGE(2) , MMP-2 and MMP-9, and increased the expression of MMP-2, MMP-9, COX-2 and HIF-1α proteins. Inhibition of HIF-1α activity by chetomin or knockdown of HIF1α gene expression by small interfering RNA markedly attenuated the production of LPS- and nicotine-stimulated PGE(2) and MMPs, as well as the expression of COX-2 and HIF-1α. Furthermore, pretreatment with inhibitors of COX-2, p38, extracellular signal-regulated kinase, Jun N-terminal kinase, protein kinase C, phosphatidylinositol 3-kinase and nuclear factor-kappaB decreased the expression of nicotine- and LPS-induced HIF-1α and COX-2, as well as the activity of PGE(2) and MMPs.
  
  
  CONCLUSIONS
  These data demonstrate novel mechanisms by which nicotine and LPS promote periodontal tissue destruction, and provide further evidence that HIF-1α is a potential target in periodontal disease associated with smoking and dental plaque.
authors.affiliation: Department of Maxillofacial Tissue Regeneration, School of Dentistry and Institute of Oral Biology, Seoul, Korea.
authors.forename: Y-S
authors.initials: YS
authors.lastname: Kim
authors.forename: S-I
authors.initials: SI
authors.lastname: Shin
authors.forename: K-L
authors.initials: KL
authors.lastname: Kang
authors.forename: J-H
authors.initials: JH
authors.lastname: Chung
authors.forename: Y
authors.initials: Y
authors.lastname: Herr
authors.forename: W-J
authors.initials: WJ
authors.lastname: Bae
authors.forename: E-C
authors.initials: EC
authors.lastname: Kim
mesh_terms: D000704:Analysis of Variance; D002461:Cell Line, Transformed; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D015232:Dinoprostone / Q000096:biosynthesis; D004357:Drug Synergism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D020935:MAP Kinase Signaling System; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D009538:Nicotine / Q000494:pharmacology*; D010513:Periodontal Ligament / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D016966:Porphyromonas gingivalis / Q000737:chemistry; D018709:Statistics, Nonparametric; D015854:Up-Regulation
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008070:Lipopolysaccharides; D009538:Nicotine; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D015232:Dinoprostone