Polymyositis (PM) and dermatomyositis (DM) are autoimmune inflammatory diseases that primarily target muscle.~autoimmune Dermatomyositis (DM) is a rare inflammatory disease that mainly affects skin, muscle, and lung.~Inflammatory myopathies (IMs) often have distinct histopathologic features suggesting humorally mediated involvement of the microcirculation in dermatomyositis (DM), including early capillary deposition of the complement C5b-9 membranolytic attack complex (MAC) and secondary ischaemic changes; and CD8 T-cell-mediated and MHC1-restricted autoimmune attack of myofibers in polymyositis (PM) and inclusion body myositis.~Plexins are a conserved family of large proteins (~200kDa) that are the canonical receptors for semaphorin molecules. Plexins are divided into four classes, A through D.~Recently, plexin and semaphorin molecules have been shown to control cell movement and cell-cell interaction in the immune system .~Extracellular vesicles (EVs) are lipid bilayer membrane vesicles that exist in various bodily fluids. EVs are released by normal, diseased, and transformed cells in vitro and in vivo and are capable of carrying lipids, proteins, mRNAs, non-coding RNAs, and even DNA. They are abundant in serum and plasma and have been a source of considerable interest as potential disease biomarkers. Normally, they maintain physiological functions by transferring biological information to neighboring cells and facilitating intercellular communication, but are also involved in the pathogenesis of numerous autoimmune diseases LC/MS analysis identified 1220 proteins in serum EVs. Of these, plexin D1 was enriched in those from PM/DM patients.
evaluation of level of serum circulating plexin D1 on extacellular vesicles in adult PM/DM patients and juvenile dermatomysitis.