title: Protein kinase A enhances lipopolysaccharide-induced IL-6, IL-8, and PGE₂ production by human gingival fibroblasts.
abstract: OBJECTIVE
  Periodontal disease is accompanied by inflammation of the gingiva and destruction of periodontal tissues, leading to alveolar bone loss in severe clinical cases. Interleukin (IL)-6, IL-8, and the chemical mediator prostaglandin E₂ (PGE₂) are known to play important roles in inflammatory responses and tissue degradation. Recently, we reported that the protein kinase A (PKA) inhibitor H-89 suppresses lipopolysaccharide (LPS)-induced IL-8 production by human gingival fibroblasts (HGFs). In the present study, the relevance of the PKA activity and two PKA-activating drugs, aminophylline and adrenaline, to LPS-induced inflammatory cytokines (IL-6 and IL-8) and PGE₂ by HGFs were examined.
  
  
  METHODS
  HGFs were treated with LPS from Porphyromonas gingivalis and H-89, the cAMP analog dibutyryl cyclic AMP (dbcAMP), aminophylline, or adrenaline. After 24 h, IL-6, IL-8, and PGE₂ levels were evaluated by ELISA.
  
  
  RESULTS
  H-89 did not affect LPS-induced IL-6 production, but suppressed IL-8 and PGE₂ production. In contrast, dbcAMP significantly increased LPS-induced IL-6, IL-8, and PGE₂ production. Up to 10 μg/ml of aminophylline did not affect LPS-induced IL-6, IL-8, or PGE₂ production, but they were significantly increased at 100 μg/ml. Similarly, 0.01 μg/ml of adrenaline did not affect LPS-induced IL-6, IL-8, or PGE₂ production, but they were significantly increased at concentrations of 0.1 and 1 μg/ml. In the absence of LPS, H-89, dbcAMP, aminophylline, and adrenaline had no relevance to IL-6, IL-8, or PGE₂ production.
  
  
  CONCLUSIONS
  These results suggest that the PKA pathway, and also PKA-activating drugs, enhance LPS-induced IL-6, IL-8, and PGE₂ production by HGFs. However, aminophylline may not have an effect on the production of these molecules at concentrations used in clinical settings (8 to 20 μg/ml in serum). These results suggest that aminophylline does not affect inflammatory responses in periodontal disease.
authors.affiliation: Department of Pharmacology, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan. ara_t@po.mdu.ac.jp
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ara
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Fujinami
authors.forename: Hiroko
authors.initials: H
authors.lastname: Urano
authors.forename: Kaname
authors.initials: K
authors.lastname: Hirai
authors.forename: Toshimi
authors.initials: T
authors.lastname: Hatori
authors.forename: Hiroo
authors.initials: H
authors.lastname: Miyazawa
mesh_terms: D000628:Aminophylline / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis*; D004789:Enzyme Activation / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005881:Gingiva / Q000166:cytology*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis*; D016209:Interleukin-8 / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D047428:Protein Kinase Inhibitors; D000628:Aminophylline; D017868:Cyclic AMP-Dependent Protein Kinases; D015232:Dinoprostone; D004837:Epinephrine