1. Rheumatology Unit, Department of Experimental and Internal Medicine, University of Messina, 98125 Messina, Italy
2. Centre for Rheumatic Disease, Kings College London, London WC2R 2LS, UK
3. Area of Immunology, Department of Functional Biology, Faculty of Medicine, University of Oviedo, 33006 Oviedo, Spain
4. Instituto de Investigacíon Sanitaria del Principado de Asturias (ISPA), 33011 Oviedo, Spain