The exosomes from OA patients were high in proteins such as Annexin A2 (ANXA2), filaggrin (FLG) and fatty acid-binding protein (FABP5), while RA-patient-derived exosomes showed a higher cargo of alpha-2-macroglobulin (A2M), apolipoprotein B (APOB) and fibronectin (FN1) proteins. Here, A2M is linked to rheumatoid arthritis.