title: Characterization of blood borne microparticles as markers of premature coronary calcification in newly menopausal women.
abstract: While the risk for symptomatic atherosclerotic disease increases after menopause, currently recognized risk factors do not identify ongoing disease processes in low-risk women. This study tested the hypothesis that circulating cell-derived microparticles may reflect disease processes in women defined as low risk by the Framingham risk score. The concentration and phenotype of circulating microparticles were evaluated in a cross-sectional study of apparently healthy menopausal women, screened for enrollment into the Kronos Early Estrogen Prevention Study. Microparticles were evaluated by flow cytometry, and coronary artery calcification (CAC) was scored using 64-slice computed tomography scanners. The procoagulant activity of isolated microparticles was determined with a sensitive fluorescent thrombin generation assay. Chronological age, body mass index, serum lipids, systolic blood pressure (Framingham risk score < 10%, range 1-3%), and high-sensitivity C-reactive protein did not differ significantly among women with low (0 < 35; range, 0.3-32 Agatston units) or high (>50; range, 93-315 Agatston units) CAC compared with women without calcification. The total concentration and percentage of microparticles derived from platelets and endothelial cells were greatest in women with high CAC scores. The thrombin-generating capacity of the isolated microparticles correlated with phosphatidylserine expression, which also was greatest in women with high CAC scores. The percentages of microparticles expressing granulocyte and monocyte markers were not significantly different among groups. Therefore, the characterization of platelet and endothelial microparticles may identify early menopausal women with premature CAC who would not otherwise be identified by the usual risk factor analysis.
authors.affiliation: Department of Surgery and Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 1st St. SW, Rochester, MN 55905, USA. jaya.m@mayo.edu
authors.forename: Muthuvel
authors.initials: M
authors.lastname: Jayachandran
authors.forename: Robert D
authors.initials: RD
authors.lastname: Litwiller
authors.forename: Whyte G
authors.initials: WG
authors.lastname: Owen
authors.forename: John A
authors.initials: JA
authors.lastname: Heit
authors.forename: Thomas
authors.initials: T
authors.lastname: Behrenbeck
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Mulvagh
authors.forename: Philip A
authors.initials: PA
authors.lastname: Araoz
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Budoff
authors.forename: S Mitchell
authors.initials: SM
authors.lastname: Harman
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Miller
mesh_terms: D000328:Adult; D017304:Annexin A5 / Q000502:physiology; D015415:Biomarkers; D001772:Blood Cell Count; D001774:Blood Chemical Analysis; D001777:Blood Coagulation / Q000502:physiology; D001792:Blood Platelets / Q000502:physiology; D002114:Calcinosis / Q000175:diagnosis / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D003331:Coronary Vessels / Q000473:pathology*; D003430:Cross-Sectional Studies; D042783:Endothelial Cells / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007202:Indicators and Reagents; D008593:Menopause / Q000502:physiology*; D008875:Middle Aged; D053758:Nanoparticles; D013917:Thrombin / Q000096:biosynthesis
chemical_list: D017304:Annexin A5; D015415:Biomarkers; D007202:Indicators and Reagents; D013917:Thrombin; D002118:Calcium