Comparison and evaluation of different methodologies and tests for detection of anti-dsDNA antibodies on 889 Slovenian patients' and blood donors' sera

Anti-double stranded DNA antibodies: A rational diagnostic approach in limited resource settings

Context

Anti-double-stranded deoxyribonucleic acid antibodies (dsDNA Abs) are highly specific markers of systemic lupus erythematosus (SLE). Multiple methods are employed for their detection in routine diagnostics.

Objectives

The aim of this study was to evaluate a diagnostic approach for anti-dsDNA Abs using DNA-ELISA and Crithidia luciliae fluorescence test (CLIFT), in combination with antinuclear antibody (ANA) screening.

Methods

We enrolled 113 patients—53 with SLE, 50 with other systemic autoimmune rheumatic diseases (OSARD), and 10 with non-autoimmune clinical conditions (NAICC).

Patients’ samples were tested for anti-dsDNA Abs using an enzyme-linked immunosorbent assay (ELISA) and CLIFT, combined to ANA screening by indirect immunofluorescence assay (ANA-IIFA).

Results

The mean age of patients was 39.94 ± 15 years (ranges: 11–85 years). Overall, specimens from 77.3%, 11.7%, and 20% of patients with SLE, OSARD and NAICC respectively were ELISA-positive; and those from 54.7% to 4% of patients with SLE and OSARD, respectively, were CLIFT-positive. CLIFT positivity was significantly associated with high ELISA titers (p = 0.002) and homogeneous ANA-IIF pattern (p = 0.0002).

Conclusion

For better clinical relevance of anti-dsDNA antibodies, we suggest a combined detection strategy based on ELISA, CLIFT and ANA-IIFA, considering the clinical criteria of SLE.

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Anti-dsDNA Abs represent an excellent indicator of systemic lupus erythematosus (SLE) activity and valuable diagnostic biomarker.

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We tested 103 autoimmune disease cases and 10 non-autoimmune condition cases for anti-dsDNA Abs using DNA and CLIFT, in combination with ANA-IIF screening.

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CLIFT positivity was significantly associated with high DNA-ELISA titers (p = 0.002) and homogeneous ANA-IIF pattern (p = 0.0002).

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High DNA-ELISA titers with a positive CLIFT are clinically relevant for the diagnosis of SLE, especially in the presence of a homogeneous ANA-IIF pattern.

IgA anti-dsDNA antibodies: A neglected serological parameter in systemic lupus erythematosus

Anti-double-stranded DNA (anti-dsDNA) autoantibodies are archetypal biomarkers found in systemic lupus erythematosus (SLE). Although they can exist in any isotype, very little is understood about the IgA isotype for which most of our knowledge is derived from observational studies. This review article summarises our knowledge of this autoantibody isotype to date. Attention will be spent on clinical associations as well as its potential links with lupus nephritis for which there is still some controversy. Further understanding of this serological parameter may facilitate diagnosis, prognosis and treatments of systemic lupus erythematosus patients.

Laboratory evaluation of anti-dsDNA antibodies

Antibodies to dsDNA are an important laboratory parameter for diagnosis, monitoring and classification of systemic lupus erythematosus (SLE). In clinical laboratories, several techniques are used to detect and quantify anti-dsDNA antibodies. Each technique has its advantages and disadvantages regarding sensitivity, specificity, avidity and assay procedure. Assays differ with respect to the antigen source (native versus synthetic versus molecular biological) used and the way the antigen is presented (e.g. in solution, covalently linked to a solid phase,…). Consequently, correlation between assays can be poor and standardization of anti-dsDNA antibody tests is challenging. We here provide an overview of the currently available anti-dsDNA tests frequently used in clinical laboratories [Crithidiae luciliae immunofluorescence test (CLIFT), Enzyme linked immune sorbent assay (ELISA), fluoroenzyme immunoassay (FEIA), chemiluminescence (CIA), multiplexed bead-based assays and Farr-RIA] and their performance characteristics. From this literature study, we concluded that performance characteristics differ between assays. Often, a combination of techniques is necessary for the best result interpretation.

Anti-dsDNA Testing Specificity for Systemic Lupus Erythematosus: A Systematic Review

BACKGROUND

Autoantibody specificity in autoimmune diseases is variable due to each patient's individual spectrum of autoantibodies and the inherent differences between detection methods and tests. Since false-positive results have downstream consequences, we conducted a comprehensive assessment of anti-double stranded DNA (anti-dsDNA) specificity from published studies of systemic lupus erythematosus (SLE).

METHODS

A systematic review (MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Database of Abstracts of Reviews of Effects) identified cross-sectional or case-control studies published January 2004 to August 2019, reporting anti-dsDNA test accuracy data in SLE. Study quality was assessed using Quality Assessment Tool for Diagnostic Accuracy Studies, version 2. A meta-analysis was conducted to estimate specificity by test method or named test where feasible.

RESULTS

Thirty studies were included covering 43 different tests. The Crithidia luciliae indirect immunofluorescence test (CLIFT) and fluorescence enzyme immunoassay methods are likely to be ≥ 90% specific (Euroimmun 97.8% (95% CI 96.2%-98.7%) 4 studies; EliA 94.7% (95% CI 91.7%-96.7%), 6 studies; CLIFT 98.7% (95% CI 96.7%-99.5%), 8 studies/7 tests]. For other test methods, specificity was not fully demonstrated to be ≥ 90% and/or the control group included healthy patients possibly overestimating specificity. More studies are required for NOVA Lite [96.0% (95% CI 87.2%-98.9%), 5 studies], chemiluminescence immunoassays [92.3% (95% CI 83.6%-96.6%), 6 studies/4 tests], multiplex immunoassays [89.3% (95% CI 86.1%-91.8%), 4 studies/2 tests], and Farr fluorescent immunoassays (no estimate, 2 studies). Specificity data reported for Farr radioimmunoassays [93.8% (95% CI 85.4-97.5%), 11 studies, 9 tests] and enzyme-linked immunosorbent assays [93.4% (95% CI 89.9%-95.7%), 15 studies/16 tests] lacked consistency.

CONCLUSION

Anti-dsDNA testing shows considerable variation in test specificity, with potential impact on the management of SLE patients. This review may help laboratory specialists and clinicians choose and interpret the appropriate anti-dsDNA test for their setting.

Toll-Like Receptor 9 Deficiency Breaks Tolerance to RNA-Associated Antigens and Up-Regulates Toll-Like Receptor 7 Protein in Sle1 Mice

Objective

Toll‐like receptors (TLRs) 7 and 9 are important innate signaling molecules with opposing roles in the development and progression of systemic lupus erythematosus (SLE). While multiple studies support the notion of a dependency on TLR‐7 for disease development, genetic ablation of TLR‐9 results in severe disease with glomerulonephritis (GN) by a largely unknown mechanism. This study was undertaken to examine the suppressive role of TLR‐9 in the development of severe lupus in a mouse model.

Methods

We crossed Sle1 lupus‐prone mice with TLR‐9–deficient mice to generate Sle1TLR‐9^−/− mice. Mice ages 4.5–6.5 months were evaluated for severe autoimmunity by assessing splenomegaly, GN, immune cell populations, autoantibody and total Ig profiles, kidney dendritic cell (DC) function, and TLR‐7 protein expression. Mice ages 8–10 weeks were used for functional B cell studies, Ig profiling, and determination of TLR‐7 expression.

Results

Sle1TLR‐9^−/− mice developed severe disease similar to TLR‐9–deficient MRL and Nba2 models. Sle1TLR‐9^−/− mouse B cells produced more class‐switched antibodies, and the autoantibody repertoire was skewed toward RNA‐containing antigens. GN in these mice was associated with DC infiltration, and purified Sle1TLR‐9^−/− mouse renal DCs were more efficient at TLR‐7–dependent antigen presentation and expressed higher levels of TLR‐7 protein. Importantly, this increase in TLR‐7 expression occurred prior to disease development, indicating a role in the initiation stages of tissue destruction.

Conclusion

The increase in TLR‐7–reactive immune complexes, and the concomitant enhanced expression of their receptor, promotes inflammation and disease in Sle1TLR9^−/− mice.

Vaccine immune response, autoimmunity and morbidity after neonatal blood exchange transfusion

INTRODUCTION

A blood exchange transfusion (BET) is most commonly performed to treat severe neonatal haemolytic disease. A distinct form of blood transfusion adverse reaction is transfusion-related immunomodulation. The purpose of our retrospective single-centre case-control cohort study was to investigate whether a blood exchange transfusion in the neonatal period provokes immunomodulation and affects humoral immune response to vaccination, morbidity and occurrence of autoantibodies.

METHODS

Study subjects were 74 apparently healthy children, who were born at term as appropriate for gestational age and received four doses of diphtheria and tetanus toxoid vaccine. Forty-one received BET due to neonatal hemolytic disease and no other blood product afterwards, while 33 did not receive any blood products. Analysis of diphtheria, tetanus and autoimmune antibodies was performed and their medical records were analyzed for infectious, allergic, cancerous and autoimmune diseases.

RESULTS

A clearly exaggerated immune response to diphtheria (1.016 IU/mL, 95% confidence interval (CI) 0.662-1.369 IU/mL vs. 0.515 IU/mL, 95% CI 0.363 to 0.626 IU/mL, P = 0.011) and slightly exaggerated immune response to tetanus vaccine (1.798 IU/mL, 95% CI 1.180-2.416 IU/mL vs. 1.036 IU/mL, 95% CI 0.398-1.673 IU/mL, P = non-specific) were observed in BET subjects. A propensity towards autoimmunity (25.8% vs. 12.5%, P = non-specific) was observed in BET subjects. However, BET in the neonatal period did not influence the occurrence of bacterial, childhood viral diseases with exception of varicella (43.9% vs. 21.2%, P = 0.040), autoimmune and cancer diseases.

CONCLUSION

BET impacted humoral immune response to diphtheria and tetanus vaccine and occurrence of autoimmune antibodies, but did not affect morbidity and the occurrence of autoimmune diseases. These effects could be related to massive antigenic load of BET and an accelerated priming of immune cells and consequent immunomodulation.

The clinical significance of plasma CFHR 1-5 in lupus nephropathy

A deficiency of complement factor H may lead to excessive consumption of C3 and an increase in C3b deposition, which are important pathological characteristics of lupus nephritis. Complement factor H-related proteins (CFHRs), comprising CFHR1 to CFHR5 (CFHR1-5), are members of the wider factor H/CFHR family. Their role in lupus nephritis remains unclear. In this study, we compared circulating levels of CFHR1-5 in 152 patients diagnosed with lupus nephritis and 20 unrelated healthy individuals to explore the relationship between the expression of CFHR1-5 and development of the disease. We found that plasma levels of CFHR3 and CFHR5 were higher in patients with lupus nephritis than in healthy individuals; also, CFHR3 and CFHR5 concentrations increased with increasing systemic lupus erythematosus disease activity index (SLEDAI) values (P < 0.05). Pearson's and Spearman's correlation test results confirmed that plasma CFHR3 and CFHR5 levels in lupus nephritis patients were positively correlated with proteinuria and levels of creatinine (Cr) and anti-dsDNA (correlation coefficients = 0.491-0.717, P < 0.05), while they were negatively correlated with plasma C3 levels and eGFR [correlation coefficients = -(0.706-0.788), P < 0.05]. Receiver operating characteristic (ROC) curve analysis results confirmed that plasma CFHR3 and CFHR5 levels were predictive of SLEDAI values and disease end points (area under the curve = 0.664-0.884, P < 0.05), with patients with both high CFHR3 and high CFHR5 exhibiting the shortest progression-free survival. Thus, both CFHR3 and CFHR5 are of prognostic value in lupus nephritis status.

A Rare Case of Malignant Mesothelioma Presenting with Systemic Lupus Erythematosus Seropositivity: A Case Report and Review of Literature

While malignant mesothelioma may initially present in a variety of ways, it is uncommon to present with systemic lupus erythematosus (SLE) seropositivity and thus obscuring its diagnosis. Our case involves a 75-year-old Caucasian male with a past medical history of essential hypertension, remote prostate cancer status post prostatectomy, and lifetime nontobacco use presenting with progressive shortness of breath over one month. After a negative cardiac assessment, a postcardiac catheterization chest X-ray (CXR) revealed a right-sided moderate-to-large pleural effusion that, on further workup, was found to be exudative. Effusion studies were negative for malignancy and bacterial growth. Recurrent accumulation of fluid after a thoracentesis one week prior prompted an autoimmune work up. Positive markers included antinuclear antibodies, anti-double stranded DNA antibodies, and anti-histone antibodies, while anti-Smith antibodies were negative. Although SLE was initially suspected based on serologies, no clinical signs or symptoms were present to fulfill the diagnosis criteria. A trial of oral prednisone resulted in decreased pleural effusion size with no further recurrence. Additional studies included a CT scan of the chest that showed pleural masses confirmed with biopsy to be epithelioid mesothelioma. Given the patient's age and new diagnosis of malignant mesothelioma, we hypothesized that the presence of autoantibodies was likely false positives due to acquired autoantibodies with age, hyperactivity of the immune system from malignancy, and possible prior asbestos exposure.

Autoantibodies Associated With Connective Tissue Diseases: What Meaning for Clinicians?

Connective tissue diseases (CTDs) such as systemic lupus erythematosus, systemic sclerosis, myositis, Sjögren's syndrome, and rheumatoid arthritis are systemic diseases which are often associated with a challenge in diagnosis. Autoantibodies (AAbs) can be detected in these diseases and help clinicians in their diagnosis. Actually, pathophysiology of these diseases is associated with the presence of antinuclear antibodies. In the last decades, many new antibodies were discovered, but their implication in pathogenesis of CTDs remains unclear. Furthermore, the classification of these AAbs is nowadays misused, as their targets can be localized outside of the nuclear compartment. Interestingly, in most cases, each antibody is associated with a specific phenotype in CTDs and therefore help in better defining either the disease subtypes or diseases activity and outcome. Because of recent progresses in their detection and in the comprehension of their pathogenesis implication in CTD-associated antibodies, clinicians should pay attention to the presence of these different AAbs to improve patient's management. In this review, we propose to focus on the different phenotypes and features associated with each autoantibody used in clinical practice in those CTDs.

Evaluation of Endothelial Cell Adhesion Molecules and Anti-C1q Antibody in Discriminating between Active and Non-Active Systemic Lupus Erythematosus

BACKGROUND

Detecting the active state of systemic lupus erythematosus (SLE) is important but challenging. This study aimed to determine the diagnostic accuracy of serum endothelial cell adhesion molecules (ICAM-1 and VCAM-1) and anti-C1q antibody in discriminating between active and non-active SLE.

METHODS

Using SELENA-SLE disease activity index (SLEDAI), 95 SLE patients (45 active and 50 non-active) were assessed. A score above five was considered indicative of active SLE. The blood samples were tested for serum ICAM-1, VCAM-1 and anti-C1q antibody using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The levels of serum VCAM-1 and anti-C1q antibody were significantly higher in active SLE patients. Both VCAM-1 and anti-C1q were able to discriminate between active and non-active SLE (p-value < 0.001 and 0.005, respectively). From the receiver operating characteristic curves (ROCs) constructed, the optimal cut-off values for VCAM-1 and anti-C1q antibody in discriminating between active and non-active SLE were 30.5 ng/mL (69.0% sensitivity, 60.0% specificity, PPV 58.5%, NPV 66.7%) and 7.86 U/mL (75.6% sensitivity, 80% specificity, PPV 77.3%, NPV 78.4%), respectively. However, serum ICAM-1 level was unable to discriminate between the two groups (p-value = 0.193).

CONCLUSION

Anti-C1q antibody demonstrated the best diagnostic accuracy in discriminating between active and non-active SLE patients.

The Usefulness of Endothelial Cell Adhesion Molecules and Anti-C1q Antibody in Monitoring Systemic Lupus Erythematosus Disease Activity

Objectives. The study was conducted to determine the correlation of ICAM-1, VCAM-1, and anti-C1q antibody levels with SLE disease activity index (SLEDAI) and standard SLE disease activity immunological markers (anti-dsDNA and sera C3 and C4). Study Design. This was a cross-sectional study. Materials and Methods. Blood samples were obtained from 95 SLE patients (45 active SLE and 50 nonactive SLE) and 50 controls. The subjects were assessed using SLEDAI and score of more than five is determined as having active SLE. The sera were tested for serum ICAM-1, VCAM-1, and anti-C1q (ELISA), anti-dsDNA (CLIFT), serum C3, and serum C4 (immunonephelometry). Results. Anti-dsDNA and anti-C1q antibody showed good positive correlations with SLEDAI (r = 0.529, P < 0.001 and r = 0.559, P < 0.001, resp.). VCAM-1 and sera C3 and C4 showed fair correlation with SLEDAI (r = 0.294, P = 0.004; r = −0.312, P = 0.002; and r = −0.382, P < 0.001, resp.). ICAM-1 level showed no significant correlation with SLEDAI (P = 0.062). There were significant correlations of VCAM-1 and anti-C1q antibody with anti-dsDNA (r = 0.226, P = 0.006 and r = 0.511, P < 0.001, resp.). VCAM-1 showed poor inverse correlation with serum C3 (r = −0.183, P = 0.028) and fair inverse correlation with serum C4 (r = −0.251, P = 0.002). Anti-C1q antibody demonstrated fair inverse correlation with both sera C3 and C4 (r = −0.420, P ≤ 0.001 and r = −0.398, P < 0.001, resp.). However, ICAM-1 showed no significant correlation with anti-dsDNA and sera C3 and C4 (P = 0.259, P = 0.626 and P = 0.338, resp.). Conclusions. The serum levels of anti-C1q antibody in SLE patients showed the best correlation with the SLEDAI and standard immunological tests for SLE disease activity. These data support that anti-C1q antibody is a useful marker for monitoring SLE global disease activity. The potential of VCAM-1 needs further confirmation.