title: Role of the complement system in rheumatoid arthritis and psoriatic arthritis: relationship with anti-TNF inhibitors.
abstract: The complement system is an essential component of innate immunity and also plays an important role in modulating adaptive immunity. It comprises more than 30 plasma and membrane-bound proteins and can be activated through three pathways: the classical, the alternative and the lectin pathways. Its activation contributes to the pathogenesis of several autoimmune and inflammatory conditions. The evidence of complement activation in synovial fluid of Rheumatoid Arthritis (RA) patients is abundant, while few data exist in Psoriatic Arthritis (PsA) patients. Levels of complement proteins are generally depressed in the synovial fluid of patients with RA, reflecting consumption of complement. On the other hand, elevated levels of several complement cleavage products have been observed in synovial fluid. Involvement of complement in the pathogenesis of RA was also confirmed in animal models of arthritis: mice deficient for complement proteins are protected against the development of collagen-induced arthritis and administration of the anti-C5 monoclonal antibody prevents the onset of this arthritis. In the last decade anti-tumor necrosis factor agents have shown to be effective for the treatment of both RA and PsA and some studies suggest that the interaction between TNFα and complement system may contribute to the pathogenesis of these diseases. Reduction of the complement activation could be one of the mechanism by which TNFα-inhibitors exert their effectiveness in inflammatory arthritides. Because of these findings, complement could be an attractive therapeutic target both in RA and in PsA.
authors.affiliation: Rheumatology, Allergology and Clinical Immunology, Department of Internal Medicine, University of Rome Tor Vergata, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Ballanti
authors.forename: Carlo
authors.initials: C
authors.lastname: Perricone
authors.forename: Gioia
authors.initials: G
authors.lastname: di Muzio
authors.forename: Barbara
authors.initials: B
authors.lastname: Kroegler
authors.forename: Maria Sole
authors.initials: MS
authors.lastname: Chimenti
authors.forename: Dario
authors.initials: D
authors.lastname: Graceffa
authors.forename: Roberto
authors.initials: R
authors.lastname: Perricone
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking; D018501:Antirheumatic Agents / Q000494:pharmacology / Q000627:therapeutic use; D001169:Arthritis, Experimental / Q000188:drug therapy / Q000235:genetics / Q000276:immunology*; D015535:Arthritis, Psoriatic / Q000188:drug therapy / Q000235:genetics / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000235:genetics / Q000276:immunology*; D003167:Complement Activation / Q000187:drug effects / Q000235:genetics; D003165:Complement System Proteins / Q000235:genetics / Q000276:immunology*; D004195:Disease Models, Animal; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D013583:Synovial Membrane / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors
chemical_list: D019138:Antibodies, Blocking; D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha; D003165:Complement System Proteins