Microparticles and their Roles in Inflammation: A Review§

Abstract

Microparticles (MPs) were long dismissed as "platelet-dust", cell debris, with no functional significance. Theyare anucleated vesicles (0.1μm to 1μm), enclosed in a membrane, secretedinto the circulation by cells during cell activation or apoptosis. They have now emerged as mediators and markers of inflammatory diseases and autoimmune disorders. They are distinctly different from exosomes and apoptotic bodiesand are released from nearly every cell type, the most abundant being platelets, leukocytes and endothelial cells. MPs can be detected using flow cytometry and more recently by nanotechnology, which is more accuratein detecting, quantifying and phenotypingMPs.MPs are instrumental in the pathogenesis of various cardiovascular diseases (thrombotic and atherosclerotic) through their pro-inflammatory and pro-coagulant properties. Their levels are significantly elevated in chronic inflammatory disorders such as rheumatoid arthritis and multiple sclerosis. However, increasing evidence suggests they also possess antiinflammatory and anti-coagulant roles which could confer immunoprotection. MPs transport various lipids, proteins, mRNA and microRNA (miRNA) which may influence activities of receiving cells. Particularly the miRNAspecies delivered by MPs have been shown to modulate inflammation.In vitro and in vivo studies are being conducted to bioengineer MPs to facilitate delivery of therapeutic compounds to desired location safely, specifically and more effectively, with fewer side effects. More research is required to understand the composition, origin, mechanisms of formation and release as well as their clearance from the circulation to pave way for gaining greater pharmacological benefits by controlling MP-mediated cellular responses.

Association Between Heart Rate Variability and Decompression-Induced Physiological Stress

“…Interestingly, leukocyte-derived microparticles (CD66b +) appears to carry an endogenous anti-inflammatory effect ( Batool et al, 2013 ). We observed a significant increase in their levels in the post decompression dataset.…”

“…This hypothesis is based on the recently accumulated knowledge about small particles (microparticles or microvesicles) shed by different cells in an organized and regulated manner. Such microparticles (MPs), which carry various nuclear components of their originating cells, like RNA and DNA, are involved in cell signaling and communication, and have recently emerged as relevant markers of inflammatory diseases (Batool et al, 2013). Variations in their levels and the cells from where they originated have been linked to an increasing range of diseases and inflammatory processes (Cognasse et al, 2015) (Puddu et al, 2010).…”

Vesicles bearing gifts: the functional importance of micro-RNA transfer in extracellular vesicles in chronic kidney disease

“…Some important antigenic markers on MPs are summarized in Table 1, and techniques for analyzing them are summarized in Table 2 and are reviewed in Ref. 15.…”

“…Well-documented contributors to the increased cardiovascular risk in patients with ESRD and CKD are endothelial dysfunction, arterial stiffness, and accelerated atherosclerosis (5,6,55). The endothelial dysfunction in ESRD may partly arise (5) as a result of the damaging effect of endotheliumderived EVs on the endothelial cells themselves, and the involvement of EVs in cardiovascular disease has been comprehensively reviewed elsewhere (15,125,126,137,144). Both in patients with preexisting coronary artery disease (152) and in hypertensive patients with impaired renal function, it has been shown that there is an increase in circulating apoptotic EMPs (defined as CD31ϩ/annexin Vϩ EMP) (71,73).…”

Complement Activation on Endothelial Cell-Derived Microparticles—A Key Determinant for Cardiovascular Risk in Patients with Systemic Lupus Erythematosus?

“…Microparticles are inflammatory buddings from cells (between 0.1 and 1 μm) [ 2 ], which themselves sustain the inflammatory reaction in autoimmune disease [ 3 ]. Microparticles are released from activated, apoptotic or dying cells by a process called blebbing whereby membrane remodelling modification and phosphatidylserine exposure result in an extrusion incorporating parental surface proteins and contents [ 4 ].…”