title: Distinct features of circulating microparticles and their relationship to clinical manifestations in systemic lupus erythematosus.
abstract: OBJECTIVE
  Characterization of the abundance, origin, and annexin V (AnxV)-binding capabilities of circulating microparticles (MPs) in SLE patients and healthy controls and to determine any associations with clinical parameters.
  
  
  METHODS
  Seventy unselected SLE patients and 29 sex- and age-matched healthy control subjects were included in the study. MPs were isolated from citrate-treated plasma and characterized by flow cytometry using AnxV or antibodies to platelet, leukocyte, or endothelial cell surface markers.
  
  
  RESULTS
  SLE patients had significantly increased concentrations of AnxV-nonbinding (AnxV-) MPs (P<0.0001), while the concentrations of total MPs (P=0.011) and AnxV-binding (AnxV+) MPs (P<0.0001) were decreased, as compared with controls. Based on flow cytometric characteristics, 2 subgroups of AnxV- MPs could be discerned: AnxV- cell-derived MPs (CDMPs) and AnxV- MPs of unknown nature (UNMPs). Both fractions were significantly increased in SLE patients (P=0.007 and P=0.0018, respectively). Platelet- and leukocyte-derived MPs were decreased in the SLE patients (P<0.0001), whereas no difference was observed for endothelial cell-derived MPs (P=0.14). The concentrations of AnxV- CDMPs correlated with the concentrations of endothelial cell-derived MPs, the disease activity score, active nephritis, hypertension, history of arterial thrombosis, and triglyceride levels (P<0.05 for all comparisons).
  
  
  CONCLUSIONS
  The concentrations and composition of MPs in SLE patients differ markedly from those in healthy subjects. Overall MP numbers were significantly decreased, but two distinct subpopulations of AnxV- MPs were significantly increased. These findings call for further characterization of MPs in SLE patients to elucidate their role in disease pathogenesis.
authors.affiliation: Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Christoffer T
authors.initials: CT
authors.lastname: Nielsen
authors.forename: Ole
authors.initials: O
authors.lastname: Østergaard
authors.forename: Christina
authors.initials: C
authors.lastname: Johnsen
authors.forename: Søren
authors.initials: S
authors.lastname: Jacobsen
authors.forename: Niels H H
authors.initials: NH
authors.lastname: Heegaard
mesh_terms: D000328:Adult; D000368:Aged; D017304:Annexin A5 / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D001792:Blood Platelets / Q000378:metabolism; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D003430:Cross-Sectional Studies; D042783:Endothelial Cells / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged
chemical_list: D017304:Annexin A5; D015415:Biomarkers