Personal non-commercial use only. The Journal of Rheumatology

ABSTRACT. Objective. Analysis of antibodies against dsDNA is an important diagnostic tool for systemic lupus erythematosus (SLE), and changes in anti-dsDNA antibody levels are also used to assess disease activity. Herein, 4 assays were compared with regard to SLE specificity, sensitivity, and association with disease activity variables. Methods. Cross-sectional sera from 178 patients with SLE, of which 11 were followed consecutively, from a regional Swedish SLE register were analyzed for immunoglobulin G (IgG) anti-dsDNA by bead-based multiplex assay (FIDIS; Theradig), fluoroenzyme-immunoassay (EliA; Phadia/Thermo Fisher Scientific), Crithidia luciliae immunofluorescence test (CLIFT; ImmunoConcepts), and line blot (EUROLINE; Euroimmun). All patients with SLE fulfilled the 1982 American College of Rheumatology and/or the 2012 Systemic Lupus International Collaborating Clinics (SLICC-12) classification criteria. Healthy individuals (n = 100), patients with rheumatoid arthritis (n = 95), and patients with primary Sjögren syndrome (n = 54) served as controls. Results. CLIFT had the highest SLE specificity (98%) whereas EliA had the highest sensitivity (35%). When cutoff levels for FIDIS, EliA, and EUROLINE were adjusted according to SLICC-12 (i.e., double the reference limit when using ELISA), the specificity and sensitivity of FIDIS was comparable to CLIFT. FIDIS and CLIFT also showed the highest concordance (84%). FIDIS performed best regarding association with disease activity in cross-sectional and consecutive samples. Fisher's exact test revealed striking differences between methods regarding associations with certain disease phenotypes. Conclusion. CLIFT remains a good choice for diagnostic purposes, but FIDIS performs equally well when the cutoff is adjusted according to SLICC-12. Based on results from cross-sectional and consecutive analyses, FIDIS can also be recommended to monitor disease activity. (First Releas

Osteopontin and disease activity in patients with recent-onset systemic lupus erythematosus:results from the SLICC Inception Cohort

Objective. In cross-sectional studies, elevated osteopontin (OPN) levels have been proposed to reflect, and/or precede, progressive organ damage and disease severity in systemic lupus erythematosus (SLE). We aimed, in a cohort of patients with recent-onset SLE, to determine whether raised serum OPN levels precede damage and/or are associated with disease activity or certain disease phenotypes. Methods. We included 344 patients from the Systemic Lupus International Collaborating Clinics (SLICC) Inception Cohort who had 5 years of followup data available. All patients fulfilled the 1997 American College of Rheumatology (ACR) criteria. Baseline sera from patients and from age- and sex-matched population-based controls were analyzed for OPN using ELISA. Disease activity and damage were assessed at each annual followup visit using the SLE Disease Activity Index 2000 (SLEDAI-2K) and the SLICC/ACR damage index (SDI), respectively. Results. Compared to controls, baseline OPN was raised 4-fold in SLE cases (p < 0.0001). After relevant adjustments in a binary logistic regression model, OPN levels failed to significantly predict global damage accrual defined as SDI ≥ 1 at 5 years. However, baseline OPN correlated with SLEDAI-2K at enrollment into the cohort (r = 0.27, p < 0.0001), and patients with high disease activity (SLEDAI-2K ≥ 5) had raised serum OPN (p < 0.0001). In addition, higher OPN levels were found in patients with persistent disease activity (p = 0.0006), in cases with renal involvement (p < 0.0001) and impaired estimated glomerular filtration rate (p = 0.01). Conclusion. The performance of OPN to predict development of organ damage was not impressive. However, OPN associated significantly with lupus nephritis and with raised disease activity at enrollment, as well as over time

Biomarkers and mediators in systemic lupus erythematosus : IFNα versus the CRP response, and evaluation of suPAR and anti-dsDNA antibody assays

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease which may affect multiple organ systems. Interferon alpha (IFNα) and autoantibodies that form immune complexes with nuclear antigens (ANA) are hallmarks believed to drive the disease into a vicious circle of inflammation, tissue damage, autoantigen exposure and autoantibody production. In SLE, the disease course is characterized by episodes of exacerbations alternating with remissions. In order to best treat the patient it is important to closely monitor symptoms and signs of disease activity. Because of the disease heterogeneity, no single biomarker has yet been found to reflect SLE disease activity in general, although antidouble stranded DNA (anti-dsDNA) antibodies sometimes indicate activity, primarily with renal involvement, and constitutes an item of the SLE disease activity score SLEDAI-2K. However, the method of anti-dsDNA measurement is not standardized and therefore varies between different laboratories. In many other inflammatory conditions, such as rheumatoid arthritis and during bacterial infections, the C-reactive protein (CRP) level is a good indicator of ongoing inflammation, but in SLE and during viral infections, CRP commonly fails to reflect the degree of inflammation. Both viral infections and SLE are characterized by IFNα, and we thus aimed to elucidate whether IFNα can inhibit CRP production. Further, four assays for anti-dsDNA antibody measurements were evaluated with regard to SLE disease specificity and activity, and a new potential biomarker of inflammation, the soluble urokinase plasminogen activator receptor (suPAR), was assessed in relation to disease activity and organ damage. An in vitro inhibitory effect of IFNα on CRP transcription and production was found in hepatocytes, and this was consolidated by in vivo studies of CRP and IFNα in sera from well-characterized SLE patients (KLURING; Kliniskt lupusregister i nordöstra Götaland). Here, CRP and disease activity were associated among patients without IFNα and without a CRP lowering gene variant (SNP rs1205). The poor disease activity compliance of CRP could therefore be explained, at least in part, by polymorphisms in the CRP gene and increased levels of IFNα. Critical differences between the methods measuring anti-dsDNA were found regarding disease specificity and ability to reflect disease activity and the results suggests the Crithidia luciliae immunofluorescence test (CLIFT) for diagnostic purposes and a bead-based multiplex assay (FIDIS) for monitoring of disease activity. Evaluation of suPAR in SLE revealed no association of suPAR with disease activity, but interestingly instead with accumulated organ damage. suPAR could therefore possibly be used to advert patients at high risk of organ damage. A detailed biological and clinical characterization of established and emerging SLE biomarkers is of importance since it may improve the clinical management as well as increase the knowledge about disease mechanisms

BIOMARKERS AND MEDIATORS IN SYSTEMIC LUPUS

IFNα versus the CRP response, and evaluation of suPAR and anti-dsDNA antibody assay

Soluble urokinase plasminogen activator receptor : A valuable biomarker in systemic lupus erythematosus?

Systemic lupus erythematosus (SLE) is a potentially severe autoimmune condition with an unpredictable disease course, often with fluctuations in disease activity over time. Long term inflammation and drug-related side-effects may subsequently lead to permanent organ damage, a consequence which is intimately connected to decreased quality of life and mortality. New lupus biomarkers that convey information regarding inflammation and/or organ damage are thus warranted. Today, there is no clinical biomarker that indicates the risk of damage accrual. Herein we highlight the urokinase plasminogen activator receptor (uPAR) and especially its soluble form (suPAR) that besides having biological functions in e.g. proteolysis, cell migration and tissue homeostasis, recently has emerged as a promising biomarker of inflammation and prognosis of several disorders. A strong association between suPAR and organ damage in SLE was recently demonstrated, and preliminary data (presented in this review) suggests the possibility of a predictive value of suPAR blood levels. The involvement of suPAR in the pathogenesis of SLE remains obscure, but its effects in leukocyte recruitment, phagocytic uptake of dying cells (efferocytosis) and complement regulation suggests that the central parts of the SLE pathogenesis could be regulated by suPAR, and vice versa

N.B.: When citing this work, cite the original article. Original Publication:

Soluble urokinase plasminogen activator receptor levels reflect organ damage in systemic lupus erythematosu

Soluble urokinase plasminogen activator receptor : A valuable biomarker in systemic lupus erythematosus?

Systemic lupus erythematosus (SLE) is a potentially severe autoimmune condition with an unpredictable disease course, often with fluctuations in disease activity over time. Long term inflammation and drug-related side-effects may subsequently lead to permanent organ damage, a consequence which is intimately connected to decreased quality of life and mortality. New lupus biomarkers that convey information regarding inflammation and/or organ damage are thus warranted. Today, there is no clinical biomarker that indicates the risk of damage accrual. Herein we highlight the urokinase plasminogen activator receptor (uPAR) and especially its soluble form (suPAR) that besides having biological functions in e.g. proteolysis, cell migration and tissue homeostasis, recently has emerged as a promising biomarker of inflammation and prognosis of several disorders. A strong association between suPAR and organ damage in SLE was recently demonstrated, and preliminary data (presented in this review) suggests the possibility of a predictive value of suPAR blood levels. The involvement of suPAR in the pathogenesis of SLE remains obscure, but its effects in leukocyte recruitment, phagocytic uptake of dying cells (efferocytosis) and complement regulation suggests that the central parts of the SLE pathogenesis could be regulated by suPAR, and vice versa

Soluble urokinase plasminogen activator receptor levels reflect organ damage in systemic lupus erythematosus

Assessments of disease activity and organ damage in systemic lupus erythematosus (SLE) remain challenging because of the lack of reliable biomarkers and disease heterogeneity. Ongoing inflammation can be difficult to distinguish from permanent organ damage caused by previous flare-ups or medication side effects. Circulating soluble urokinase plasminogen activator receptor (suPAR) has emerged as a potential marker of inflammation and disease severity, and an outcome predictor in several disparate conditions. This study was done to evaluate suPAR as a marker of disease activity and organ damage in SLE. Sera from 100 healthy donors- and 198 patients with SLE fulfilling the 1982 American College of Rheumatology classification criteria and/or the Fries criteria were analyzed for suPAR by enzyme immunoassay. Eighteen patients with varying degree of disease activity were monitored longitudinally. Disease activity was assessed by the SLE disease activity index 2000 and the physicians global assessment. Organ damage was evaluated by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology damage index (SDI). Compared with healthy control subjects, serum suPAR levels were elevated significantly in patients with SLE. No association was recorded regarding suPAR levels and SLE disease activity in cross-sectional or consecutive samples. However, a strong association was observed between suPAR and SDI (P andlt; 0.0005). Considering distinct SDI domains, renal, neuropsychiatric, ocular, skin, and peripheral vascular damage had.a significant effect on suPAR levels. This study is the first to demonstrate an association between serum suPAR and irreversible organ damage in SLE. Further studies are warranted to evaluate suPAR and other biomarkers as predictors of evolving organ damage.Funding Agencies|Swedish Research Council|K2012-69X-14594-10-3|County Council of Ostergotland||Swedish Society of Medicine||Swedish Society for Medical Research||Swedish Rheumatism Association||King Gustaf V 80-Year, Clas Groschinsky, Ingrid Svensson, Bror Karlsson, Gunnar Trosell, Magn. Bergvall, Sigurd Elsa Golje||Nanna Svartz research foundations||</p