The complement system in systemic lupus erythematosus: an update.
The complement system plays a major role in the autoimmune disease, systemic lupus erythematosus (SLE). However, the role of complement in SLE is complex since it may both prevent and exacerbate the disease. In this review, we explore the latest findings in complement-focused research in SLE. C1q deficiency is the strongest genetic risk factor for SLE, although such deficiency is very rare. Various recently discovered genetic associations include mutations in the complement receptors 2 and 3 as well as complement inhibitors, the latter related to earlier onset of nephritis. Further, autoantibodies are a distinct feature of SLE that are produced as the result of an adaptive immune response and how complement can affect that response is also being reviewed. SLE generates numerous disease manifestations involving contributions from complement such as glomerulonephritis and the increased risk of thrombosis. Furthermore, since most of the complement system is present in plasma, complement is very accessible and may be suitable as biomarker for diagnosis or monitoring of disease activity. This review highlights the many roles of complement for SLE pathogenesis and how research has progressed during recent years.
Division of Medical Protein Chemistry, Department of Laboratory Medicine Malmö, Lund University, Malmö, Sweden Division of Cell Biology and Immunology, Telethon Kids Institute, University of Western Australia, Subiaco, Australia.
Jonatan
J
Leffler
Department of Clinical Sciences, Section of Rheumatology, Lund University, Skåne University Hospital Lund, Lund, Sweden.
Anders A
AA
Bengtsson
Division of Medical Protein Chemistry, Department of Laboratory Medicine Malmö, Lund University, Malmö, Sweden.
Anna M
AM
Blom
D056704:Adaptive Immunity; D017209:Apoptosis / Q000276:immunology; D015922:Complement C1q / Q000172:deficiency; D003169:Complement Inactivator Proteins / Q000235:genetics; D003165:Complement System Proteins / Q000276:immunology*; D020022:Genetic Predisposition to Disease; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000276:immunology*; D009154:Mutation; D011951:Receptors, Complement / Q000235:genetics
D003169:Complement Inactivator Proteins; D011951:Receptors, Complement; D015922:Complement C1q; D003165:Complement System Proteins
Autoantibodies; Inflammation; Systemic Lupus Erythematosus