The complement system in systemic lupus erythematosus: an update

Abstract

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.

Complement levels and anti-C1q autoantibodies in patients with neuropsychiatric systemic lupus erythematosus

“…A correlation between renal involvement and circulating immune complexes (CIC), complement deposits and levels of anti-C1q has been found in SLE. [1][2][3] However, the pathogenic role of all these complement components in other organs, including the nervous system, is less clear.…”

Analysis of interleukin 19 serum levels and single nucleotide polymorphisms in systemic lupus erythematosus

“…Therefore, it is very important to screen and investigate the genes that are related to SLE susceptibility. Additionally, some researchers think that the serum IL-19 level can affect normal kidney activity and cause SLE (Barrett et al, 2009;Leffler et al, 2014) (Leffler, Bengtsson, and Blom 2014;Barrett et al, 2009). To explore the correlation between the serum IL-19 level, SNPs, and SLE, the rs2243188 locus was investigated in the present paper.…”

A brief insight into systemic lupus erythematosus pathogenesis

“…Specifically, in SLE the alternative pathway is preferentially activated, its selective inhibition being beneficial -probably due to positive effects of the activation of classic and lectin pathway [17,39].…”

“…This dual role is manifested in SLE through protection achieved by clearance of immune complexes and apoptotic debris and destruction, which through its products, mediates the inflammatory process developed in the kidney and other target organs [17].…”

“…The alternative pathway of complement system activation [17] and oxidative stress [18] are also considered noteworthy participants in SLE pathogenesis.…”