title: Prolyl hydroxylase inhibitors increase the production of vascular endothelial growth factor by periodontal fibroblasts.
abstract: OBJECTIVE
  Pharmacological inhibitors of prolyl hydroxylases (PHDs) can induce a proangiogenic response that favors wound healing and bone regeneration. However, the response of periodontal cells to PHD inhibitors is unknown.
  
  
  METHODS
  To determine the effects of PHD inhibitors on periodontal cells, we exposed human fibroblasts from the gingiva and the periodontal ligament to dimethyloxallyl glycine, desferrioxamine, l-mimosine and CoCl(2). Viability, proliferation, and protein synthesis were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), [(3)H]thymidine, and [(3)H]leucine incorporation, respectively. The levels of Ki67, hypoxia-inducible factor 1α (HIF-1α), p27, phosphorylated c-Jun N-terminal kinase (JNK) and phosphorylated p38 were determined by immunohistochemistry and western blotting. Vascular endothelial growth factor (VEGF) mRNA levels were measured by quantitative PCR. Protein levels of VEGF and interleukin (IL)-6 were evaluated by immunoassays.
  
  
  RESULTS
  We found that PHD inhibitors, while leaving cell viability unchanged, reduced proliferation and protein synthesis. This was paralleled by decreased Ki67 levels and increased p27 levels, suggesting that PHD inhibitors provoke growth arrest. Independently from this response, PHD inhibitors stabilized HIF-1α and increased the production of VEGF. This increase of VEGF was observed in the presence of proinflammatory IL-1 and pharmacological inhibitors of JNK and p38 signaling. Moreover, PHD inhibitors did not modulate expression of IL-6 and the phosphorylation of JNK and p38.
  
  
  CONCLUSIONS
  These results suggest that PHD inhibitors enhance the production of VEGF in periodontal fibroblasts, even in the presence of proinflammatory IL-1. The data further suggest that PHD inhibitors do not provoke a significant proinflammatory or anti-inflammatory response in this in vitro setting.
authors.affiliation: Department of Oral Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Agis
authors.forename: G
authors.initials: G
authors.lastname: Watzek
authors.forename: R
authors.initials: R
authors.lastname: Gruber
mesh_terms: D000600:Amino Acids, Dicarboxylic / Q000494:pharmacology; D016587:Antimutagenic Agents / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000032:analysis; D003676:Deferoxamine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects*; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000032:analysis; D018836:Inflammation Mediators / Q000032:analysis; D007375:Interleukin-1 / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D048031:JNK Mitogen-Activated Protein Kinases / Q000032:analysis; D019394:Ki-67 Antigen / Q000032:analysis; D008898:Mimosine / Q000494:pharmacology; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects*; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors*; D047428:Protein Kinase Inhibitors / Q000032:analysis; D011506:Proteins / Q000187:drug effects; D017262:Siderophores / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000187:drug effects*; D048051:p38 Mitogen-Activated Protein Kinases / Q000032:analysis
chemical_list: D000600:Amino Acids, Dicarboxylic; D016587:Antimutagenic Agents; D004791:Enzyme Inhibitors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D018836:Inflammation Mediators; D007375:Interleukin-1; D015850:Interleukin-6; D019394:Ki-67 Antigen; D047428:Protein Kinase Inhibitors; D011506:Proteins; D017262:Siderophores; D042461:Vascular Endothelial Growth Factor A; D050760:Cyclin-Dependent Kinase Inhibitor p27; D003035:Cobalt; D008898:Mimosine; D011393:Procollagen-Proline Dioxygenase; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C018021:cobaltous chloride; D003676:Deferoxamine; C040947:oxalylglycine