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Coss SL, Zhou D, Chua GT, Aziz RA, Hoffman RP, Wu YL, Ardoin SP, Atkinson JP, Yu CY. The complement system and human autoimmune diseases. J Autoimmun 2023; 137:102979. [PMID: 36535812 PMCID: PMC10276174 DOI: 10.1016/j.jaut.2022.102979] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 12/11/2022] [Indexed: 12/23/2022]
Abstract
Genetic deficiencies of early components of the classical complement activation pathway (especially C1q, r, s, and C4) are the strongest monogenic causal factors for the prototypic autoimmune disease systemic lupus erythematosus (SLE), but their prevalence is extremely rare. In contrast, isotype genetic deficiency of C4A and acquired deficiency of C1q by autoantibodies are frequent among patients with SLE. Here we review the genetic basis of complement deficiencies in autoimmune disease, discuss the complex genetic diversity seen in complement C4 and its association with autoimmune disease, provide guidance as to when clinicians should suspect and test for complement deficiencies, and outline the current understanding of the mechanisms relating complement deficiencies to autoimmunity. We focus primarily on SLE, as the role of complement in SLE is well-established, but will also discuss other informative diseases such as inflammatory arthritis and myositis.
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Affiliation(s)
- Samantha L Coss
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University, Columbus, OH, USA.
| | - Danlei Zhou
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University, Columbus, OH, USA
| | - Gilbert T Chua
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Rabheh Abdul Aziz
- Department of Pediatrics, The Ohio State University, Columbus, OH, USA; Department of Allergy, Immunology and Rheumatology, University of Buffalo, NY, USA
| | - Robert P Hoffman
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University, Columbus, OH, USA
| | - Yee Ling Wu
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University, Columbus, OH, USA; Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Stacy P Ardoin
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University, Columbus, OH, USA
| | - John P Atkinson
- Department of Medicine, Division of Rheumatology, Washington University School of Medicine, St Louis, MO, USA
| | - Chack-Yung Yu
- Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University, Columbus, OH, USA.
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Ekdahl KN, Persson B, Mohlin C, Sandholm K, Skattum L, Nilsson B. Interpretation of Serological Complement Biomarkers in Disease. Front Immunol 2018; 9:2237. [PMID: 30405598 PMCID: PMC6207586 DOI: 10.3389/fimmu.2018.02237] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 09/10/2018] [Indexed: 01/07/2023] Open
Abstract
Complement system aberrations have been identified as pathophysiological mechanisms in a number of diseases and pathological conditions either directly or indirectly. Examples of such conditions include infections, inflammation, autoimmune disease, as well as allogeneic and xenogenic transplantation. Both prospective and retrospective studies have demonstrated significant complement-related differences between patient groups and controls. However, due to the low degree of specificity and sensitivity of some of the assays used, it is not always possible to make predictions regarding the complement status of individual patients. Today, there are three main indications for determination of a patient's complement status: (1) complement deficiencies (acquired or inherited); (2) disorders with aberrant complement activation; and (3) C1 inhibitor deficiencies (acquired or inherited). An additional indication is to monitor patients on complement-regulating drugs, an indication which may be expected to increase in the near future since there is now a number of such drugs either under development, already in clinical trials or in clinical use. Available techniques to study complement include quantification of: (1) individual components; (2) activation products, (3) function, and (4) autoantibodies to complement proteins. In this review, we summarize the appropriate indications, techniques, and interpretations of basic serological complement analyses, exemplified by a number of clinical disorders.
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Affiliation(s)
- Kristina N Ekdahl
- Rudbeck Laboratory C5:3, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.,Centre of Biomaterials Chemistry, Linnaeus University, Kalmar, Sweden
| | - Barbro Persson
- Rudbeck Laboratory C5:3, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Camilla Mohlin
- Centre of Biomaterials Chemistry, Linnaeus University, Kalmar, Sweden
| | - Kerstin Sandholm
- Centre of Biomaterials Chemistry, Linnaeus University, Kalmar, Sweden
| | - Lillemor Skattum
- Section of Microbiology, Immunology and Glycobiology, Department of Laboratory Medicine, Clinical Immunology and Transfusion Medicine, Lund University, Lund, Sweden
| | - Bo Nilsson
- Rudbeck Laboratory C5:3, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
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Complement diagnostics: concepts, indications, and practical guidelines. Clin Dev Immunol 2012; 2012:962702. [PMID: 23227092 PMCID: PMC3511841 DOI: 10.1155/2012/962702] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 10/17/2012] [Indexed: 12/11/2022]
Abstract
Aberrations in the complement system have been shown to be direct or indirect pathophysiological mechanisms in a number of diseases and pathological conditions such as autoimmune disease, infections, cancer, allogeneic and xenogeneic transplantation, and inflammation. Complement analyses have been performed on these conditions in both prospective and retrospective studies and significant differences have been found between groups of patients, but in many diseases, it has not been possible to make predictions for individual patients because of the lack of sensitivity and specificity of many of the assays used. The basic indications for serological diagnostic complement analysis today may be divided into three major categories: (a) acquired and inherited complement deficiencies; (b) disorders with complement activation; (c) inherited and acquired C1INH deficiencies. Here, we summarize indications, techniques, and interpretations for basic complement analyses and present an algorithm, which we follow in our routine laboratory.
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Donnelly S, Roake W, Brown S, Young P, Naik H, Wordsworth P, Isenberg DA, Reid KBM, Eggleton P. Impaired recognition of apoptotic neutrophils by the C1q/calreticulin and CD91 pathway in systemic lupus erythematosus. ACTA ACUST UNITED AC 2006; 54:1543-56. [PMID: 16645988 DOI: 10.1002/art.21783] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE A deficiency in a subcomponent of C1q can result in increased susceptibility to autoimmune diseases such as systemic lupus erythematosus (SLE). The monocyte endocytic receptor CD91 is implicated in the endocytosis of apoptotic neutrophils via interactions with C1q and calreticulin. In this clinical study, we studied the binding of C1q to leukocytes and determined whether C1q bound specifically to calreticulin and CD91 on cells undergoing apoptosis in SLE. METHODS Proximal antibody phage display, calreticulin-transfected cells, and immunocytochemical and confocal techniques were used in a comprehensive analysis of direct binding of C1q to apoptotic neutrophils that were obtained from healthy individuals and from patients with SLE. In addition, apoptotic cellular systems were assessed in vitro. RESULTS C1q appeared to colocalize to apoptotic blebs on the surface of leukocytes in association with both calreticulin and CD91, as determined by phage display and transfected cell studies. However, C1q did not bind to apoptotic cells isolated from SLE patients, despite the positivity of the cells for both calreticulin and CD91. Surface expression of calreticulin decreased on neutrophils as they aged, but increased on monocytes. In an apoptotic phagocytic assay, the addition of C1q and calreticulin significantly enhanced the phagocytosis of apoptotic cell debris by monocyte-derived cells. CONCLUSION These observations indicate that neutrophils from SLE patients have a reduced ability to be recognized and removed by the C1q/calreticulin/CD91-mediated apoptotic pathway, despite the presence of main apoptotic recognition partners. This suggests that an additional component, as yet unidentified, acts as a C1q binding partner on apoptotic cells, and this component may be lacking in cells isolated from SLE patients.
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Arason GJ, Kolka R, Hreidarsson AB, Gudjonsson H, Schneider PM, Fry L, Arnason A. Defective prevention of immune precipitation in autoimmune diseases is independent of C4A*Q0. Clin Exp Immunol 2005; 140:572-9. [PMID: 15932521 PMCID: PMC1809379 DOI: 10.1111/j.1365-2249.2005.02794.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Increased prevalence of C4 null alleles is a common feature of autoimmune diseases. We have shown previously that complement-dependent prevention of immune precipitation (PIP) is defective in patients with systemic lupus erythematosus (SLE), and correlated this defect with C4A*Q0 and low levels of the C4A isotype. To further clarify the role of C4A in the aetiology of SLE, we now extend our studies to other diseases which have been associated with C4A*Q0. The frequency of C4A*Q0 was increased in Icelandic patients with coeliac disease (0.50; P < 0.001), Grave's disease (0.30; P = 0.002) and insulin-dependent diabetes mellitus (0.23; P = 0.04) and in British patients with dermatitis herpetiformis (0.42; P = 0.002) and this was reflected in low levels of C4A. In spite of this, PIP was normal in these patients, and in marked contrast to our previous observations on connective tissue diseases, PIP measurements in these patient groups correlated more strongly with levels of C4B (r = 0.51, P = 0.0000004) than C4A. Patients with increased levels of anti-C1q antibodies had significantly lower PIP than patients without such antibodies (P < 0.01) and a negative association of PIP with anti-C1q antibodies was also reflected in an increased prevalence (P = 0.006) and levels (P = 0.006) of anti-C1q antibodies in patients with subnormal PIP, as well as a negative correlation between PIP and anti-C1q antibodies (r = - 0.25, P = 0.02). These results show that the PIP defect cannot be explained by low levels of C4A alone and suggest that measurements of anti-C1q antibodies may be useful in future studies on the molecular cause of the PIP defect in autoimmune connective tissue disease.
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Affiliation(s)
- G J Arason
- Department of Immunology, Institute of Laboratory Medicine, Reykjavik, Iceland.
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Seelen MA, Trouw LA, Daha MR. Diagnostic and prognostic significance of anti-C1q antibodies in systemic lupus erythematosus. Curr Opin Nephrol Hypertens 2003; 12:619-24. [PMID: 14564199 DOI: 10.1097/00041552-200311000-00008] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW The presence of a wide variety of autoantibodies is a characteristic finding in systemic lupus erythematosus. Autoantibodies against nuclear proteins, such as anti-nuclear and anti-double-stranded DNA antibodies, are used as diagnostic markers in systemic lupus erythematosus. Renal involvement is frequently found in systemic lupus erythematosus and is an important risk factor for death. Therefore, markers for the diagnosis and follow-up of nephritis are very important. Anti-C1q autoantibodies are strongly associated with renal involvement in systemic lupus erythematosus. This study will review recent findings on the pathogenic role and clinical importance of anti-C1q antibodies in lupus nephritis. RECENT FINDINGS Recent clinical studies have clearly emphasized the diagnostic relevance of anti-C1q autoantibody levels in patients with lupus nephritis. With a possible negative predictive value of 100%, anti-C1q autoantibodies are the only exclusive antibodies associated with the involvement of a single organ in systemic lupus erythematosus. Next to the clinical findings, the pathogenic significance of anti-C1q antibodies has been shown in an animal model. The deposition of autologous C1q in healthy glomeruli of mice after the infusion of anti-C1q antibodies induces moderate tissue damage. SUMMARY The latest insight into the pathogenesis of anti-C1q autoantibodies in the development of lupus nephritis and the recently demonstrated clinical importance of anti-C1q autoantibodies for the diagnosis of lupus nephritis support the value of further investigations. New diagnostic methods for the detection of anti-C1q and an accurate follow-up of antibody levels might be of use in clinical practice.
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Affiliation(s)
- Marc A Seelen
- Department of Nephrology, Leiden University Medical Center, The Netherlands.
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Horváth L, Czirják L, Fekete B, Jakab L, Prohászka Z, Cervenak L, Romics L, Singh M, Daha MR, Füst G. Levels of antibodies against C1q and 60 kDa family of heat shock proteins in the sera of patients with various autoimmune diseases. Immunol Lett 2001; 75:103-9. [PMID: 11137133 DOI: 10.1016/s0165-2478(00)00287-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previously a strong positive correlation was found between antibodies to C1q (C1qAb) and antibodies against human heat shock protein (hsp60) and mycobacterial hsp65 in HIV infected patients. Here the levels of these antibodies were measured in the sera of patients with different autoimmune diseases (122 systemic lupus erythematosus (SLE), 55 systemic sclerosis, 33 undifferentiated connective tissue disease (UCTD), 27 primary Raynaud syndrome, 21 rheumatoid arthritis (RA), 14 polymyositis/dermatomyositis (PM/DM), and 192 healthy blood donors. The prevalence of IgG C1qAb was found to be high (P<0.0001 as compared to the healthy controls) only in the SLE group. The levels of the anti-hsp60 (P=0.0094) and anti-hsp65 (P=0.0108) antibodies were high only in the UCTD patients. No correlation was found between the C1qAb and anti-hsp antibodies in any group except a significant (P=0.011) positive correlation between C1qAb and hsp65 antibodies in the patients with UCTD. These findings indicate that the autoantibodies against C1q are heterogeneous: in different diseases different types of C1qAb may dominate.
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Affiliation(s)
- L Horváth
- 3rd Department of Medicine, Faculty of Medicine, Semmelweis University, Kútvölgyi út 4, H-1125, Budapest, Hungary
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Mollnes TE, Haga HJ, Brun JG, Nielsen EW, Sjöholm A, Sturfeldt G, Mårtensson U, Bergh K, Rekvig OP. Complement activation in patients with systemic lupus erythematosus without nephritis. Rheumatology (Oxford) 1999; 38:933-40. [PMID: 10534542 DOI: 10.1093/rheumatology/38.10.933] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE To study the association between disease activity and complement activation prospectively in patients with systemic lupus erythematosus (SLE). PATIENTS AND METHODS Twenty-one SLE patients were examined monthly for 1 yr. Disease activity, autoantibodies, conventional complement tests and the following complement activation products were investigated: C1rs-C1inh complexes, C4bc, Bb, C3a, C3bc, C5a and the terminal SC5b-9 complement complex (TCC). RESULTS Modest variation in disease activity was noted. None of the patients had nephritis. Flare was observed at 27 visits. Four patients had anti-C1q antibodies in conjunction with modestly low C1q concentrations. The complement parameters were rather constant during the observation period. Slightly to moderately decreased C4 (0.05-0.10 g/l) was found in 10 patients and severely decreased C4 (<0.05 g/l) in seven patients. Decreased C4 was not associated with increased complement activation. Complement activation products were either normal or slightly elevated. TCC was the only activation product correlating significantly with score for disease activity at flare. None of the variables tested predicted flares. CONCLUSION Complement tests are of limited importance in routine examination of SLE without nephritis, although TCC is suggested to be one of the most sensitive markers for disease activity.
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Affiliation(s)
- T E Mollnes
- Department of Immunology and Transfusion Medicine, Nordland Central Hospital, Bodø, Norway
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von Mühlen CA, Chan EK, Anglés-Cano E, Mamula MJ, Garcia-De La Torre I, Fritzler MJ. Advances in autoantibodies in SLE. Lupus 1998; 7:507-14. [PMID: 9863891 DOI: 10.1191/096120398678920613] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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