title: Isorhamnetin inhibits Prevotella intermedia lipopolysaccharide-induced production of interleukin-6 in murine macrophages via anti-inflammatory heme oxygenase-1 induction and inhibition of nuclear factor-κB and signal transducer and activator of transcription 1 activation.
abstract: OBJECTIVE
  Interleukin-6 (IL-6) is a key proinflammatory cytokine that has been considered to be important in the pathogenesis of periodontal disease. Therefore, host-modulatory agents directed at inhibiting IL-6 appear to be beneficial in terms of attenuating periodontal disease progression and potentially improving disease susceptibility. In the current study, we investigated the effect of the flavonoid isorhamnetin on the production of IL-6 in murine macrophages stimulated with lipopolysaccharide (LPS) from Prevotella intermedia, a pathogen implicated in inflammatory periodontal disease, and its mechanisms of action.
  
  
  METHODS
  Lipopolysaccharide from P. intermedia ATCC 25611 was isolated using the standard hot phenol-water method. Culture supernatants were collected and assayed for IL-6. We used real-time PCR to quantify IL-6 and heme oxygenase-1 (HO-1) mRNA expression. The expression of HO-1 protein and the levels of signaling proteins were monitored using immunoblot analyses. The DNA-binding activity of nuclear factor-κB (NF-κB) was analyzed using ELISA-based assay kits.
  
  
  RESULTS
  Isorhamnetin significantly down-regulated P. intermedia LPS-induced production of IL-6 as well as its mRNA expression in RAW264.7 cells. Isorhamnetin up-regulated the expression of HO-1 at both gene transcription and translation levels in cells stimulated with P. intermedia LPS. In addition, inhibition of HO-1 activity by tin protoporphyrin IX blocked the inhibitory effect of isorhamnetin on IL-6 production. Isorhamnetin failed to prevent LPS from activating either c-Jun N-terminal kinase or p38 pathways. Isorhamnetin did not inhibit NF-κB transcriptional activity at the level of inhibitory κB-α degradation. Isorhamnetin suppressed NF-κB signaling through inhibition of nuclear translocation and DNA binding activity of NF-κB p50 subunit and attenuated signal transducer and activator of transcription 1 signaling.
  
  
  CONCLUSIONS
  Although further research is required to clarify the detailed mechanism of action, we propose that isorhamnetin may contribute to blockade of the host-destructive processes mediated by IL-6 and could be a highly efficient modulator of the host response in the treatment of inflammatory periodontal disease. Further research in animal models of periodontitis is required to better evaluate, the potential of isorhamnetin as a novel agent for treating periodontal disease.
authors: Department of Biological Science, College of Medical and Life Sciences, Silla University, Busan, Korea.
authors: J Y
authors: JY
authors: Jin
authors: E Y
authors: EY
authors: Choi
authors: H R
authors: HR
authors: Park
authors: J I
authors: JI
authors: Choi
authors: I S
authors: IS
authors: Choi
authors: S J
authors: SJ
authors: Kim
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000975:Antioxidants / Q000494:pharmacology*; D002460:Cell Line; D015536:Down-Regulation; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000187:drug effects*; D020672:I-kappa B Proteins / Q000187:drug effects; D048031:JNK Mitogen-Activated Protein Kinases / Q000187:drug effects; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors*; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000187:drug effects*; D008665:Metalloporphyrins / Q000494:pharmacology; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D052002:NF-kappa B p50 Subunit / Q000187:drug effects; D018713:Prevotella intermedia / Q000276:immunology*; D014176:Protein Biosynthesis / Q000187:drug effects; D011524:Protoporphyrins / Q000494:pharmacology; D011794:Quercetin / Q000031:analogs & derivatives* / Q000494:pharmacology; D050794:STAT1 Transcription Factor / Q000037:antagonists & inhibitors*; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects; D000093242:Interleukin-6 Inhibitors
chemical_list: D000893:Anti-Inflammatory Agents; D000975:Antioxidants; D004791:Enzyme Inhibitors; D051547:Heme Oxygenase-1; D020672:I-kappa B Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D008665:Metalloporphyrins; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D011524:Protoporphyrins; D011794:Quercetin; D050794:STAT1 Transcription Factor; D048051:p38 Mitogen-Activated Protein Kinases; D000093242:Interleukin-6 Inhibitors; C047368:3-methylquercetin; C032628:tin protoporphyrin IX; C496542:Hmox1 protein, mouse
keywords: Prevotella intermedia; heme oxygenase-1; interleukin-6; isorhamnetin; nuclear factor-κB; signal transducer and activator of transcription 1