title: The CO donor CORM-2 inhibits LPS-induced vascular cell adhesion molecule-1 expression and leukocyte adhesion in human rheumatoid synovial fibroblasts.
abstract: OBJECTIVE
  Infection with Gram-negative bacteria has been recognized as an initiator of rheumatoid arthritis, which is characterized by chronic inflammation and infiltration of immune cells. Carbon monoxide (CO) exhibits anti-inflammatory properties. Here we have investigated the detailed mechanisms of vascular cell adhesion molecule-1 (VCAM-1) expression induced by LPS and if CO inhibited LPS-induced leukocyte adhesion to synovial fibroblasts by suppressing VCAM-1 expression.
  
  
  METHODS
  Human rheumatoid arthritis synovial fibroblasts (RASFs) were incubated with LPS and/or the CO-releasing compound CORM-2. Effects of LPS on VCAM-1 levels were determined by analysing mRNA expression, promoter activity, protein expression, and immunohistochemical staining. The molecular mechanisms were investigated by determining the expression, activation, and binding activity of transcriptional factors using target signal antagonists.
  
  
  RESULTS
  CORM-2 significantly inhibited inflammatory responses in LPS-treated RASFs by down-regulating the expression of adhesion molecule VCAM-1 and leukocyte infiltration. The down-regulation of LPS-induced VCAM-1 expression involved inhibition of the expression of phosphorylated-NF-κB p65 and AP-1 (p-c-Jun, c-Jun and c-Fos mRNA levels). These results were confirmed by chromatin immunoprecipitation assay to detect NF-κB and AP-1 DNA binding activity.
  
  
  CONCLUSIONS
  LPS-mediated formation of the TLR4/MyD88/TRAF6/c-Src complex regulated NF-κB and MAPKs/AP-1 activation leading to VCAM-1 expression and leukocyte adhesion. CORM-2, which liberates CO to elicit direct biological activities, attenuated LPS-induced VCAM-1 expression by interfering with NF-κB and AP-1 activation, and significantly reduced LPS-induced immune cell infiltration of the synovium.
authors.affiliation: Department of Physiology and Pharmacology and Health Ageing Research Center, College of Medicine, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan.
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Chi
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Chuang
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Chen
authors.forename: Chih-Chung
authors.initials: CC
authors.lastname: Lin
authors.forename: Li-Der
authors.initials: LD
authors.lastname: Hsiao
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
mesh_terms: D000818:Animals; D018501:Antirheumatic Agents / Q000378:metabolism / Q000494:pharmacology*; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001665:Binding Sites; D002248:Carbon Monoxide / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects*; D002478:Cells, Cultured; D018920:Coculture Techniques; D015536:Down-Regulation; D004789:Enzyme Activation; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008813:Mice, Inbred ICR; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D009942:Organometallic Compounds / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D015398:Signal Transduction / Q000187:drug effects; D013583:Synovial Membrane / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D018501:Antirheumatic Agents; D008070:Lipopolysaccharides; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D009942:Organometallic Compounds; C498143:RELA protein, human; C495345:TLR4 protein, human; D048029:TNF Receptor-Associated Factor 6; D051197:Toll-Like Receptor 4; D018808:Transcription Factor AP-1; D051996:Transcription Factor RelA; D019010:Vascular Cell Adhesion Molecule-1; C447082:tricarbonyldichlororuthenium (II) dimer; D002248:Carbon Monoxide; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases
keywords: LPS; VCAM-1; carbon monoxide; leukocyte adhesion