OBJECTIVE: In addition to releasing proteins and mediators, cells also release membrane vesicles (exosomes and apoptotic blebs) into the extracellular environment. Apoptotic blebs contain multiple autoantigens, but few data are available concerning the protein content of exosomes. Exosomes are formed during an immune response and can directly stimulate T cells or bind to dendritic cells. The aim of this study was to identify the nature of synovial exosomes from patients with different rheumatic diseases and to examine their potential autoantigenic content, which may be involved in the induction of an autoimmune response. METHODS: Synovial exosomes from patients with rheumatoid arthritis (RA), patients with reactive arthritis, and patients with osteoarthritis were purified, analyzed by electron microscopy, and labeled with immunogold to detect IgG and IgM molecules. Autoantigen content was identified by 2-dimensional electrophoresis-immunoblotting and subsequent mass spectrometry. In order to investigate the presence of citrullinated proteins, immunoblotting with anticitrulline antibodies was performed. RESULTS: Citrullinated proteins were observed in all exosome preparations, in contrast to other autoantigenic proteins (e.g., BiP and heterogeneous nuclear RNP A2) that were previously observed in RA and other autoimmune diseases. These citrullinated proteins included the fibrin alpha-chain fragment, fibrin beta-chain, fibrinogen beta-chain precursor, fibrinogen D fragment, and the Sp alpha (CD5 antigen-like protein) receptor. Purification of synovial exosomes led to the detection of citrullinated fibrinogen and citrullinated Sp alpha associated with IgM and IgG. CONCLUSION: Synovial exosomes contain citrullinated proteins, which are known to be autoantigens in RA. Although immune mechanisms in which exosomes carry citrullinated peptides could play an important role in the induction and distribution of citrullinated proteins, there must be a specific recognition of these proteins that is unique to the RA immune system.
OBJECTIVE: In addition to releasing proteins and mediators, cells also release membrane vesicles (exosomes and apoptotic blebs) into the extracellular environment. Apoptotic blebs contain multiple autoantigens, but few data are available concerning the protein content of exosomes. Exosomes are formed during an immune response and can directly stimulate T cells or bind to dendritic cells. The aim of this study was to identify the nature of synovial exosomes from patients with different rheumatic diseases and to examine their potential autoantigenic content, which may be involved in the induction of an autoimmune response. METHODS: Synovial exosomes from patients with rheumatoid arthritis (RA), patients with reactive arthritis, and patients with osteoarthritis were purified, analyzed by electron microscopy, and labeled with immunogold to detect IgG and IgM molecules. Autoantigen content was identified by 2-dimensional electrophoresis-immunoblotting and subsequent mass spectrometry. In order to investigate the presence of citrullinated proteins, immunoblotting with anticitrulline antibodies was performed. RESULTS: Citrullinated proteins were observed in all exosome preparations, in contrast to other autoantigenic proteins (e.g., BiP and heterogeneous nuclear RNP A2) that were previously observed in RA and other autoimmune diseases. These citrullinated proteins included the fibrin alpha-chain fragment, fibrin beta-chain, fibrinogen beta-chain precursor, fibrinogen D fragment, and the Sp alpha (CD5 antigen-like protein) receptor. Purification of synovial exosomes led to the detection of citrullinated fibrinogen and citrullinated Sp alpha associated with IgM and IgG. CONCLUSION: Synovial exosomes contain citrullinated proteins, which are known to be autoantigens in RA. Although immune mechanisms in which exosomes carry citrullinated peptides could play an important role in the induction and distribution of citrullinated proteins, there must be a specific recognition of these proteins that is unique to the RA immune system.
Authors: Altan Ercan; Jing Cui; Dereck E W Chatterton; Kevin D Deane; Melissa M Hazen; William Brintnell; Colin I O'Donnell; Lezlie A Derber; Michael E Weinblatt; Nancy A Shadick; David A Bell; Ewa Cairns; Daniel H Solomon; V Michael Holers; Pauline M Rudd; David M Lee Journal: Arthritis Rheum Date: 2010-08
Authors: María Yáñez-Mó; Pia R-M Siljander; Zoraida Andreu; Apolonija Bedina Zavec; Francesc E Borràs; Edit I Buzas; Krisztina Buzas; Enriqueta Casal; Francesco Cappello; Joana Carvalho; Eva Colás; Anabela Cordeiro-da Silva; Stefano Fais; Juan M Falcon-Perez; Irene M Ghobrial; Bernd Giebel; Mario Gimona; Michael Graner; Ihsan Gursel; Mayda Gursel; Niels H H Heegaard; An Hendrix; Peter Kierulf; Katsutoshi Kokubun; Maja Kosanovic; Veronika Kralj-Iglic; Eva-Maria Krämer-Albers; Saara Laitinen; Cecilia Lässer; Thomas Lener; Erzsébet Ligeti; Aija Linē; Georg Lipps; Alicia Llorente; Jan Lötvall; Mateja Manček-Keber; Antonio Marcilla; Maria Mittelbrunn; Irina Nazarenko; Esther N M Nolte-'t Hoen; Tuula A Nyman; Lorraine O'Driscoll; Mireia Olivan; Carla Oliveira; Éva Pállinger; Hernando A Del Portillo; Jaume Reventós; Marina Rigau; Eva Rohde; Marei Sammar; Francisco Sánchez-Madrid; N Santarém; Katharina Schallmoser; Marie Stampe Ostenfeld; Willem Stoorvogel; Roman Stukelj; Susanne G Van der Grein; M Helena Vasconcelos; Marca H M Wauben; Olivier De Wever Journal: J Extracell Vesicles Date: 2015-05-14
Authors: Suresh Mathivanan; Justin W E Lim; Bow J Tauro; Hong Ji; Robert L Moritz; Richard J Simpson Journal: Mol Cell Proteomics Date: 2009-10-16 Impact factor: 5.911
Authors: Katleen Van Steendam; Kelly Tilleman; Marlies De Ceuleneer; Filip De Keyser; Dirk Elewaut; Dieter Deforce Journal: Arthritis Res Ther Date: 2010-07-07 Impact factor: 5.156