**4. Role of Microparticles in Inflammatory Joint Diseases**

Rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA) are chronic immune-mediated inflammations, leading to chronic joint inflammations and/or enthesopathies and to many extra-articular complications. Increasing numbers of circulating microparticles in immune-mediated diseases have been reported; the increase is particularly manifested if vessels are also affected; it usually concerns microparticles of platelet origin and—less frequently—those of endothelial origin [40–46]. The few studies conducted to date have suggested, or even confirmed, a pathogenic link between microparticles and immune-dependent diseases [6–10,47,48]. MPs can be detected in inflammatory joint diseases in blood and other biological fluids (Table 2).



aCCP—anti cyclic citrullinated peptide antibodies; AS—ankylosing spondylitis; CD—cluster of differentiation; MPMs—monocyte-derived microparticles; PMPs—platelet-derived microparticles; PsA—psoriatic arthritis; RA—rheumatoid arthritis; JIA—juvenile idiopathic arthritis.
