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Mouliou DS. C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians. Diseases 2023; 11:132. [PMID: 37873776 PMCID: PMC10594506 DOI: 10.3390/diseases11040132] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/15/2023] [Accepted: 09/19/2023] [Indexed: 10/25/2023] Open
Abstract
The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.
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Jia RF, Li L, Li H, Cao XJ, Ruan Y, Meng S, Wang JY, Jin ZN. Meta-analysis of C-Reactive Protein and Risk of Angina Pectoris. Am J Cardiol 2020; 125:1039-1045. [PMID: 32014245 DOI: 10.1016/j.amjcard.2020.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/29/2019] [Accepted: 01/03/2020] [Indexed: 11/16/2022]
Abstract
Associations between elevated C-reactive protein (CRP) levels and the angina pectoris risk have been reported for many years, but the results remain controversial. To address this issue, a meta-analysis was therefore conducted. Eligible studies were identified by searching PubMed, EMBASE, Cochrane library, and web of science up to January 2019. Altogether, 10 prospective cohort studies and 11 case-control studies were included, and they were published from 1997 to 2013 and summed up to 18,316 samples totally. The pooled mean difference of CRP levels was 4.44 (95% confidence interval 2.71 to 6.17) between angina patients and healthy controls. The combined odds ratio of CRP for major adverse cardiac events in angina patients was 1.67 (95% CI 1.23 to 2.26). In conclusion, the meta-analysis indicated that elevated CRP levels were associated with angina pectoris, especially unstable angina pectoris, and were probably a risk factor of major adverse cardiac events.
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Affiliation(s)
- Ruo-Fei Jia
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Long Li
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Hong Li
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xiao-Jing Cao
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yang Ruan
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Shuai Meng
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jia-Yu Wang
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Ze-Ning Jin
- Department of Cardiovascular, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
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Dinter F, Burdukiewicz M, Schierack P, Lehmann W, Nestler J, Dame G, Rödiger S. Simultaneous detection and quantification of DNA and protein biomarkers in spectrum of cardiovascular diseases in a microfluidic microbead chip. Anal Bioanal Chem 2019; 411:7725-7735. [PMID: 31760445 PMCID: PMC6881413 DOI: 10.1007/s00216-019-02199-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/30/2019] [Accepted: 10/08/2019] [Indexed: 12/19/2022]
Abstract
The rapid and simultaneous detection of DNA and protein biomarkers is necessary to detect the outbreak of a disease or to monitor a disease. For example, cardiovascular diseases are a major cause of adult mortality worldwide. We have developed a rapidly adaptable platform to assess biomarkers using a microfluidic technology. Our model mimics autoantibodies against three proteins, C-reactive protein (CRP), brain natriuretic peptide (BNP), and low-density lipoprotein (LDL). Cell-free mitochondrial DNA (cfmDNA) and DNA controls are detected via fluorescence probes. The biomarkers are covalently bound on the surface of size- (11–15 μm) and dual-color encoded microbeads and immobilized as planar layer in a microfluidic chip flow cell. Binding events of target molecules were analyzed by fluorescence measurements with a fully automatized fluorescence microscope (end-point and real-time) developed in house. The model system was optimized for buffers and immobilization strategies of the microbeads to enable the simultaneous detection of protein and DNA biomarkers. All prime target molecules (anti-CRP, anti-BNP, anti-LDL, cfmDNA) and the controls were successfully detected both in independent reactions and simultaneously. In addition, the biomarkers could also be detected in spiked human serum in a similar way as in the optimized buffer system. The detection limit specified by the manufacturer is reduced by at least a factor of five for each biomarker as a result of the antibody detection and kinetic experiments indicate that nearly 50 % of the fluorescence intensity is achieved within 7 min. For rapid data inspection, we have developed the open source software digilogger, which can be applied for data evaluation and visualization. Graphical abstract ![]()
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Affiliation(s)
- Franziska Dinter
- Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968, Senftenberg, Germany
| | - Michał Burdukiewicz
- Faculty of Mathematics and Informations Science, Warsaw University of Technology, plac Politechniki 1, 00-661, Warsaw, Poland
| | - Peter Schierack
- Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968, Senftenberg, Germany
| | | | - Jörg Nestler
- BiFlow Systems GmbH, Technologie-Campus 1, 09126, Chemnitz, Germany
| | - Gregory Dame
- Institute of Microbiology and Virology-Brandenburg Medical School Theodor Fontane, Universitätsplatz 1, 01968, Senftenberg, Germany
| | - Stefan Rödiger
- Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968, Senftenberg, Germany. .,Faculty of Health Sciences, joint Faculty of the Brandenburg University of Technology Cottbus - Senftenberg, the Brandenburg Medical School Theodor Fontane and the University of Potsdam, Berlin, Germany.
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Singh SK, Agrawal A. Functionality of C-Reactive Protein for Atheroprotection. Front Immunol 2019; 10:1655. [PMID: 31379851 PMCID: PMC6646712 DOI: 10.3389/fimmu.2019.01655] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/03/2019] [Indexed: 12/14/2022] Open
Abstract
C-reactive protein (CRP) is a pentameric molecule made up of identical monomers. CRP can be seen in three different forms: native pentameric CRP (native CRP), non-native pentameric CRP (non-native CRP), and monomeric CRP (mCRP). Both native and non-native CRP execute ligand-recognition functions for host defense. The fate of any pentameric CRP after binding to a ligand is dissociation into ligand-bound mCRP. If ligand-bound mCRP is proinflammatory, like free mCRP has been shown to be in vitro, then mCRP along with the bound ligand must be cleared from the site of inflammation. Once pentameric CRP is bound to atherogenic low-density lipoprotein (LDL), it reduces both formation of foam cells and proinflammatory effects of atherogenic LDL. A CRP mutant, that is non-native CRP, which readily binds to atherogenic LDL, has been found to be atheroprotective in a murine model of atherosclerosis. Thus, unlike statins, a drug that can lower only cholesterol levels but not CRP levels should be developed. Since non-native CRP has been shown to bind to all kinds of malformed proteins in general, it is possible that non-native CRP would be protective against all inflammatory states in which host proteins become pathogenic. If it is proven through experimentation employing transgenic mice that non-native CRP is beneficial for the host, then using a small-molecule compound to target CRP with the goal of changing the conformation of endogenous native CRP would be preferred over using recombinant non-native CRP as a biologic to treat diseases caused by pathogenic proteins such as oxidized LDL.
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Affiliation(s)
| | - Alok Agrawal
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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Luan YY, Yao YM. The Clinical Significance and Potential Role of C-Reactive Protein in Chronic Inflammatory and Neurodegenerative Diseases. Front Immunol 2018; 9:1302. [PMID: 29951057 PMCID: PMC6008573 DOI: 10.3389/fimmu.2018.01302] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 05/25/2018] [Indexed: 12/17/2022] Open
Abstract
C-reactive protein (CRP) is an acute-phase protein synthesized by hepatocytes in response to pro-inflammatory cytokines during inflammatory/infectious processes. CRP exists in conformationally distinct forms such as the native pentameric CRP and monomeric CRP (mCRP) and may bind to distinct receptors and lipid rafts and exhibit different functional properties. It is known as a biomarker of acute inflammation, but many large-scale prospective studies demonstrate that CRP is also known to be associated with chronic inflammation. This review is focused on discussing the clinical significance of CRP in chronic inflammatory and neurodegenerative diseases, such as cardiovascular disease, type 2 diabetes mellitus, age-related macular degeneration, hemorrhagic stroke, Alzheimer’s disease, and Parkinson’s disease, including recent advances on the implication of CRP and its forms specifically on the pathogenesis of these diseases. Overall, we highlight the advances in these areas that may be translated into promising measures for the diagnosis and treatment of inflammatory diseases.
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Affiliation(s)
- Ying-Yi Luan
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing, China
| | - Yong-Ming Yao
- Trauma Research Center, First Hospital Affiliated to the Chinese PLA General Hospital, Beijing, China.,State Key Laboratory of Kidney Disease, The Chinese PLA General Hospital, Beijing, China
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Shi P, Li XX, Zhu W, Yang H, Dong C, Li XM. Immunohistochemical staining reveals C-reactive protein existing predominantly as altered conformation forms in inflammatory lesions. ACTA BIOLOGICA HUNGARICA 2014; 65:265-73. [PMID: 25194730 DOI: 10.1556/abiol.65.2014.3.3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
C-reactive protein (CRP) is an established marker of inflammation and has been proposed to play a proinflammatory role in pathologies of several diseases. CRP is primarily produced by the liver and released into circulation as a pentameric molecule composed of five identical subunits. It has been suggested that the activation of the proinflammatory actions of CRP requires sequential conformational changes triggered by local inflammatory conditions. These include the dissociation into the subunit form (monomeric CRP, mCRP) and further reduction of the intra-subunit disulfide bond of mCRP. This model predicts that mCRP is the primary isoform present in inflamed but not healthy tissues, however the supporting evidence is lacking. Herein, we stained tissue samples across multiple anatomical locations from several types of human diseases with highly selective monoclonal antibodies that can differentiate CRP and mCRP. The results indicated that mCRP is the predominant form existing in the lesions. Further immunoblotting of the patient tissue samples revealed the potential presence of reduced mCRP. Together, we conclude that mCRP but not CRP is the major isoform present in local inflammatory lesions, supporting the so-called cascading model of CRP function and regulation.
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Affiliation(s)
- Ping Shi
- The Second Hospital of Lanzhou University Lanzhou 730000 PR China
| | - Xiao-Xin Li
- The Second Hospital of Lanzhou University Lanzhou 730000 PR China
| | - Wei Zhu
- The Second Hospital of Lanzhou University Lanzhou 730000 PR China
| | - Hong Yang
- The Second Hospital of Lanzhou University Lanzhou 730000 PR China
| | - Chi Dong
- The Second Hospital of Lanzhou University Lanzhou 730000 PR China
| | - Xiao-Ming Li
- The Second Hospital of Lanzhou University Lanzhou 730000 PR China
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7
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Regulated conformation changes in C-reactive protein orchestrate its role in atherogenesis. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11434-012-5591-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Gheita TA, El-Gazzar II, Azkalany G, El-Fishawy HS, El-Faramawy A. High-sensitivity C-reactive protein (hs-CRP) in systemic lupus erythematosus patients without cardiac involvement; relation to disease activity, damage and intima-media thickness. EGYPTIAN RHEUMATOLOGIST 2012. [DOI: 10.1016/j.ejr.2012.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Sjöwall C, Cardell K, Boström EA, Bokarewa MI, Enocsson H, Ekstedt M, Lindvall L, Frydén A, Almer S. High prevalence of autoantibodies to C-reactive protein in patients with chronic hepatitis C infection: association with liver fibrosis and portal inflammation. Hum Immunol 2012; 73:382-8. [PMID: 22333691 DOI: 10.1016/j.humimm.2012.01.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 01/12/2012] [Accepted: 01/24/2012] [Indexed: 02/08/2023]
Abstract
The presence of autoantibodies against C-reactive protein (anti-CRP) has been reported in association with autoimmunity and histopathology in chronic hepatitis C virus (HCV) infection. Resistin could play a role in the pathogenesis of hepatitis, although results on HCV infection are ambiguous. Here we retrospectively analyzed anti-CRP and resistin levels in the sera of 38 untreated and well-characterized HCV patients at the time of their first liver biopsy. HCV activity and general health were assessed by a physician at least yearly until follow-up ended. Anti-CRP and resistin were also measured in patients with autoimmune hepatitis (AIH) and nonalcoholic fatty liver disease (NAFLD). Anti-CRP antibodies were registered in all HCV patients, whereas only a few AIH (11%) and NAFLD (12%) sera were positive. Anti-CRP levels were related to histopathological severity and were highest in patients with cirrhosis at baseline. Resistin levels were similar in HCV, AIH, and NAFLD patients, but high levels of resistin were associated with early mortality in HCV patients. Neither anti-CRP nor resistin predicted a response to interferon-based therapy or cirrhosis development or was associated with liver-related mortality. We conclude that anti-CRP antibodies are frequently observed in chronic HCV infection and could be a useful marker of advanced fibrosis and portal inflammation.
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Affiliation(s)
- Christopher Sjöwall
- Rheumatology/AIR, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
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10
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Lakota K, Zigon P, Mrak-Poljsak K, Rozman B, Shoenfeld Y, Sodin-Semrl S. Antibodies against acute phase proteins and their functions in the pathogenesis of disease: A collective profile of 25 different antibodies. Autoimmun Rev 2011; 10:779-89. [DOI: 10.1016/j.autrev.2011.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 06/15/2011] [Indexed: 01/09/2023]
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11
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Zen M, Bassi N, Campana C, Bettio S, Tarricone E, Nalotto L, Ghirardello A, Doria A. Protective molecules and their cognate antibodies: new players in autoimmunity. AUTO- IMMUNITY HIGHLIGHTS 2010; 1:63-72. [PMID: 26000109 PMCID: PMC4389047 DOI: 10.1007/s13317-010-0010-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 09/08/2010] [Indexed: 12/21/2022]
Abstract
Impairment of the clearance of apoptotic material seems to contribute to autoantigen exposure, which can initiate or maintain an autoimmune response in predisposed individuals. Complement component C1q, Creactive protein (CRP), serum amyloid P (SAP), mannose-binding lectin (MBL), apolipoprotein A-1 (Apo A-1) and long pentraxin 3 (PTX3) are molecules involved in the removal of apoptotic bodies and pathogens, and in other antiinflammatory pathways. For this reason they have been called "protective" molecules. C1q has a key role in the activation of the complement cascade and acts as a bridging molecule between apoptotic bodies and macrophages favouring phagocytosis. In addition to other functions, CRP, SAP and MBL bind to the surface of numerous pathogens as well as cellular debris and activate the complement cascade, thus stimulating their clearance by immune cells. The role of PTX3 is more controversial. In fact, PTX also promotes the clearance of microorganisms, but the activation of the complement cascade through C1q and removal of apoptotic material can be either stimulated or inhibited by this molecule. Antibodies against protective molecules have been recently reported in systemic lupus erythematosus and other autoimmune rheumatic diseases. Some of them seem to be pathogenetic and others protective. Thus, protective molecules and their cognate antibodies may constitute a regulatory network involved in autoimmunity. Dysregulation of this system might contribute to the development of autoimmune diseases in predisposed individuals.
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Affiliation(s)
- Margherita Zen
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
| | - Nicola Bassi
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
| | - Carla Campana
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
| | - Silvano Bettio
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
| | - Elena Tarricone
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
| | - Linda Nalotto
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
| | - Anna Ghirardello
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
| | - Andrea Doria
- Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
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Lakota K, Thallinger GG, Cucnik S, Bozic B, Mrak-Poljsak K, Ambrozic A, Rozman B, Blinc A, Tomsic M, Sodin-Semrl S. Could antibodies against Serum Amyloid A function as physiological regulators in humans? Autoimmunity 2010; 44:149-58. [DOI: 10.3109/08916934.2010.487504] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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13
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Sjöwall C, Zickert A, Skogh T, Wetterö J, Gunnarsson I. Serum levels of autoantibodies against C-reactive protein correlate with renal disease activity and response to therapy in lupus nephritis. Arthritis Res Ther 2009; 11:R188. [PMID: 20003354 PMCID: PMC3003497 DOI: 10.1186/ar2880] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2009] [Revised: 12/03/2009] [Accepted: 12/11/2009] [Indexed: 01/08/2023] Open
Abstract
Introduction Serum levels of C-reactive protein (CRP) seldom reflect disease activity in systemic lupus erythematosus (SLE). We have previously shown that autoantibodies against neo-epitopes of CRP often occur in SLE, but that this does not explain the modest CRP response seen in flares. However, we have repeatedly found that anti-CRP levels parallel lupus disease activity, with highest levels in patients with renal involvement; thus, we aimed to study anti-CRP in a material of well-characterized lupus nephritis patients. Methods Thirty-eight patients with lupus nephritis were included. Treatment with corticosteroids combined with cyclophosphamide, mycophenolate mofetil or rituximab was started after baseline kidney biopsy. A second biopsy was taken after ≥ 6 months. Serum creatinine, cystatin C, complement, anti-dsDNA, anti-CRP and urinalysis were done on both occasions. Biopsies were evaluated regarding World Health Organisation (WHO) class and indices of activity and chronicity. Renal disease activity was estimated using the British Isles Lupus Assessment Group (BILAG) index. Results At baseline, 34/38 patients had renal BILAG-A; 4/38 had BILAG-B. Baseline biopsies showed WHO class III (n = 8), IV (n = 19), III to IV/V (n = 3) or V (n = 8) nephritis. Seventeen out of 38 patients were anti-CRP-positive at baseline, and six at follow-up. Overall, anti-CRP levels had dropped at follow-up (P < 0.0001) and anti-CRP levels correlated with renal BILAG (r = 0.29, P = 0.012). A positive anti-CRP test at baseline was superior to anti-dsDNA and C1q in predicting poor response to therapy as judged by renal BILAG. Baseline anti-CRP levels correlated with renal biopsy activity (r = 0.33, P = 0.045), but not with chronicity index. Anti-CRP levels were positively correlated with anti-dsDNA (fluorescence-enhanced immunoassay: r = 0.63, P = 0.0003; Crithidia luciliae immunofluorescence microscopy test: r = 0.44, P < 0.0001), and inversely with C3 (r = 0.35, P = 0.007) and C4 (r = 0.29, P = 0.02), but not with C1q (r = 0.14, P = 0.24). No associations with urinary components, creatinine, cystatin C or the glomerular filtration rate were found. Conclusions In the present study, we demonstrate a statistically significant correlation between anti-CRP levels and histopathological activity in lupus nephritis, whereas a baseline positive anti-CRP test predicted poor response to therapy. Our data also confirm previous findings of associations between anti-CRP and disease activity. This indicates that anti-CRP could be helpful to assess disease activity and response to therapy in SLE nephritis, and highlights the hypothesis of a pathogenetic role for anti-CRP antibodies in lupus nephritis.
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Affiliation(s)
- Christopher Sjöwall
- Rheumatology/AIR, Clinical and Experimental Medicine, Linköping University, SE-581 85 Linköping, Sweden.
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14
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Singh SK, Suresh MV, Hammond DJ, Rusiñol AE, Potempa LA, Agrawal A. Binding of the monomeric form of C-reactive protein to enzymatically-modified low-density lipoprotein: effects of phosphoethanolamine. Clin Chim Acta 2009; 406:151-5. [PMID: 19545552 DOI: 10.1016/j.cca.2009.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 06/11/2009] [Accepted: 06/12/2009] [Indexed: 01/11/2023]
Abstract
BACKGROUND The 5 subunits of native pentameric C-reactive protein (CRP) are dissociated to generate the monomeric form of CRP (mCRP) in some in vitro conditions, both physiological and non-physiological, and also in vivo. Many bioactivities of mCRP generated by urea-treatment of CRP and of mCRP generated by mutating the primary structure of CRP have been reported. The bioactivities of mCRP generated by spontaneous dissociation of CRP are largely unexplored. METHODS We purified mCRP generated by spontaneous dissociation of CRP and investigated the binding of mCRP to enzymatically-modified low-density lipoprotein (E-LDL). RESULTS mCRP was approximately 60 times more potent than CRP in binding to E-LDL. In the presence of the small-molecule compound phosphoethanolamine (PEt), at 37 degrees C, the binding of mCRP to E-LDL was enhanced <2-fold, while the binding of CRP to E-LDL was enhanced >10-fold. In contrast, PEt inhibited the binding of both CRP and mCRP to pneumococcal C-polysaccharide, another phosphocholine-containing ligand to which CRP and mCRP were found to bind. We have not investigated yet whether PEt alters the structure of CRP at 37 degrees C. CONCLUSIONS Combined data suggest that the targeting of CRP with the aim to monomerize CRP in vivo may be an effective approach to capture modified forms of LDL.
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Affiliation(s)
- Sanjay K Singh
- Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States
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15
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The fundamental flaws of immunoassays and potential solutions using tandem mass spectrometry. J Immunol Methods 2009; 347:3-11. [PMID: 19538965 DOI: 10.1016/j.jim.2009.06.003] [Citation(s) in RCA: 392] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 05/21/2009] [Accepted: 06/05/2009] [Indexed: 12/26/2022]
Abstract
Immunoassays have made it possible to measure dozens of individual proteins and other analytes in human samples for help in establishing the diagnosis and prognosis of disease. In too many cases the results of those measurements are misleading and can lead to unnecessary treatment or missed opportunities for therapeutic interventions. These cases stem from problems inherent to immunoassays performed with human samples, which include a lack of concordance across platforms, autoantibodies, anti-reagent antibodies, and the high-dose hook effect. Tandem mass spectrometry may represent a detection method capable of alleviating many of the flaws inherent to immunoassays. We review our understanding of the problems associated with immunoassays on human specimens and describe methodologies using tandem mass spectrometry that could solve some of those problems. We also provide a critical discussion of the potential pitfalls of novel mass spectrometric approaches in the clinical laboratory.
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