title: Microparticles as mediators and biomarkers of rheumatic disease.
abstract: Microparticles (MPs) are small membrane-bound vesicles that arise from activated and dying cells and enter the blood to display pro-inflammatory and pro-thrombotic activities. MPs are 0.1-1.0 μm in size and incorporate nuclear, cytoplasmic and membrane molecules as they detach from cells. This process can occur with cell activation as well as cell death, with particles likely corresponding to blebs that form on the cell surface during apoptosis. To measure particle expression, flow cytometry allows determination of particle numbers based on size as well as surface markers that denote the cell of origin; platelet MPs are usually the most abundant type in blood. As shown in in vitro and in vivo systems, MPs can promote inflammation and thrombosis resulting from their content of cytokines like IL-1 and pro-coagulant molecules like tissue factor. Certain particle types can be anti-inflammatory, however, suggesting a range of immunomodulatory activities depending on the cell of origin. Studies on patients with a wide range of rheumatic disease show increased MP numbers in blood, with platelet and endothelial particles associated with vascular manifestations; increased numbers of particles also occur in the joint fluid where they may drive cytokine production and activate synoviocytes. In autoimmune diseases such as SLE and RA, MPs may also contribute to disease pathogenesis by the formation of immune complexes. MPs thus represent novel subcellular structures that can impact on the pathogenesis of rheumatic disease and serve as biomarkers of underlying cellular disturbances.
authors.affiliation: Medical Research Service, Durham Veterans Administration Medical Center, Durham, NC 27705, USA. dpiset@acpub.duke.edu
authors.forename: David S
authors.initials: DS
authors.lastname: Pisetsky
authors.forename: Anirudh J
authors.initials: AJ
authors.lastname: Ullal
authors.forename: Julie
authors.initials: J
authors.lastname: Gauley
authors.forename: Tony C
authors.initials: TC
authors.lastname: Ning
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D055252:Cell-Derived Microparticles / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D012216:Rheumatic Diseases / Q000276:immunology* / Q000378:metabolism
chemical_list: D015415:Biomarkers