Platelets Amplify Inflammation in Arthritis via Collagen-Dependent Microparticle Production

Platelet Microparticles Drive Inflammatory Arthritis Platelets are best known for their critical role in blood clot formation during wound repair, but an appreciation for their role in inflammatory processes is growing. Platelet-derived cellular microparticles (MPs) are small membrane vesicles released from platelets in response to cell activation that can transport biomolecules throughout the body that have also been implicated in inflammatory processes. Boilard et al. (p. 580 ; see the Perspective by Zimmerman and Weyrich ) have now found that platelet-derived MPs probably contribute to the inflammatory processes underlying rheumatoid arthritis, an autoimmune disease. The majority of MPs in synovial fluid from patients with various types of inflammatory arthritis were platelet-derived and, importantly, platelet-derived MPs were lacking in synovial fluid from osteoarthritis patients. Furthermore, platelet depletion abrogated disease development in a mouse model of inflammatory arthritis.