title: In vitro and clinical studies examining the expression of osteopontin in cigarette smoke-exposed endothelial cells and cigarette smokers.
abstract: BACKGROUND
  Cigarette smoking is a leading cause of mortality and morbidity and is associated with cardiovascular disease via contributory processes such as endothelial dysfunction, inflammation and thrombosis. Cigarette smoke both contains and stimulates the production of cellular oxidants and it may also promote vascular inflammation. Osteopontin is a non-collagenous matrix protein first identified in bone and there is increasing evidence for its role in inflammation and cardiovascular disease via its action as a soluble cytokine.
  
  
  METHODS
  In this study we have examined the mechanisms underlying the expression of osteopontin in human vascular endothelial cells in vitro following exposure to cigarette smoke particulate matter (PM), using PCR, electrochemiluminescence, immunostaining and Western blotting. We further determined if serum osteopontin levels changed in humans who quit smoking.
  
  
  RESULTS
  Non-cytotoxic concentrations of PM increased osteopontin levels in cultured human endothelial cells and this effect was reduced in the presence of ascorbate, suggesting a role for oxidants in the response to PM. However, oxidant production played no role in the PM-evoked induction MMP-3, an enzyme which cleaves osteopontin. In smokers who quit smoking for 5 days, serum osteopontin levels were significantly lowered compared to those measured prior to smoking cessation.
  
  
  CONCLUSIONS
  In vitro cigarette smoke extract exposure induced osteopontin expression in human endothelial cells in an oxidative stress-dependent manner, which may involve MMP-3 cleavage. In humans, serum osteopontin was decreased with short-term smoking cessation. Endothelial-derived osteopontin may contribute to inflammation in smokers, and may also contribute to atherosclerosis and cardiovascular disease-related processes.
authors.affiliation: British American Tobacco, Group Research and Development, Regents Park Road, Southampton SO15 8TL, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Bishop
authors.forename: Eugenia H
authors.initials: EH
authors.lastname: Theophilus
authors.forename: Ian M
authors.initials: IM
authors.lastname: Fearon
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D015153:Blotting, Western; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D055664:Electrochemical Techniques; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D008875:Middle Aged; D053495:Osteopontin / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012906:Smoke / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects* / Q000097:blood / Q000235:genetics; D016540:Smoking Cessation; D000074606:Smoking Prevention; D013997:Time Factors; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D000975:Antioxidants; C506895:SPP1 protein, human; D012906:Smoke; D053495:Osteopontin; C511768:MMP3 protein, human; D019278:Matrix Metalloproteinase 3; D001205:Ascorbic Acid