Predictive value of anti-dsDNA autoantibodies: Importance of the assay

Humanized Mouse Models of Systemic Lupus Erythematosus: Opportunities and Challenges

Animal models have played a crucial role in the understanding of the mechanisms and treatments of human diseases; however, owing to the large differences in genetic background and disease-specific characteristics, animal models cannot fully simulate the occurrence and progression of human diseases. Recently, humanized immune system mice, based on immunodeficient mice, have been developed that allow for the partial reconstruction of the human immune system and mimic the human in vivo microenvironment. Systemic lupus erythematosus (SLE) is a complex disease characterized by the loss of tolerance to autoantigens, overproduction of autoantibodies, and inflammation in multiple organ systems. The detailed immunological events that trigger the onset of clinical manifestations in patients with SLE are still not well known. Two methods have been adopted for the development of humanized SLE mice. They include transferring peripheral blood mononuclear cells from patients with SLE to immunodeficient mice or transferring human hematopoietic stem cells to immunodeficient mice followed by intraperitoneal injection with pristane to induce lupus. However, there are still several challenges to be overcome, such as how to improve the efficiency of reconstruction of the human B cell immune response, how to extend the lifespan and improve the survival rate of mice to extend the observation period, and how to improve the development of standardized commercialized models and use them. In summary, there are opportunities and challenges for the development of humanized mouse models of SLE, which will provide novel strategies for understanding the mechanisms and treatments of SLE.

Performance Characteristics of Different Anti-Double-Stranded DNA Antibody Assays in the Monitoring of Systemic Lupus Erythematosus

Objective

We sought to evaluate different anti-double-stranded DNA assays for their performance characteristics in monitoring disease activity fluctuations in systemic lupus erythematosus (SLE).

Methods

36 active SLE patients were followed monthly. At each study visit (total n = 371), blood was collected and disease activity was scored using the SELENA-SLEDAI (excluding anti-dsDNA or complement components) and by a physician's global assessment (PGA). Four anti-dsDNA tests were compared. Linear mixed-effects models with random intercept and fixed slopes were used to evaluate the relationship between the longitudinal fluctuations of disease activity and anti-dsDNA titers.

Results

At enrollment, positivity for QUANTA Lite and high-avidity anti-dsDNA assay was both 64% and significantly lower than anti-dsDNA positivity by QUANTA Flash (83%) and CLIFT (96%). Linear mixed-effects modeling indicated that the change in clinical SELENA-SLEDAI scores was associated with the titers of all anti-dsDNA with QUANTA Flash yielding the highest marginal R² (0.15; p < 0.01). QUANTA Flash was the only anti-dsDNA assay significantly associated with the change in PGA (marginal R² = 0.05; p < 0.01).

Conclusion

These data indicate that anti-dsDNA antibodies determined by QUANTA Flash have a value in monitoring SLE disease activity.

Mechanisms of atherosclerosis and cardiovascular disease in antiphospholipid syndrome and systemic lupus erythematosus. New therapeutic approaches

Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are 2 highly related autoimmune-rheumatic diseases associated with an increased risk of developing cardiovascular (CV) diseases. Despite the great progresses made in understanding the pathological mechanisms leading to CV diseases in those pathologies, there is still the unmet need to improve long term prognosis. CV diseases in SLE and APS is thought to happen as the result of a complex interaction between traditional CV risk factors, immune deregulation and disease activity, including the synergic effect of cytokines, chemokines, adipokines, proteases, autoantibodies, adhesion receptors, oxidative stress and a plethora of intracellular signalling molecules. Genomic and epigenomic analyses have further allowed the identification of specific signatures explaining the proathero-thrombotic profiles of APS and SLE patients. This review examines the complex role of these heterogeneous factors, and analyses new therapeutic approaches under study to reduce the CV risk in these autoimmune disorders.

Next-Generation Autoantibody Testing by Combination of Screening and Confirmation-the CytoBead® Technology

Occurrence of autoantibodies (autoAbs) is a hallmark of autoimmune diseases, and the analysis thereof is an essential part in the diagnosis of organ-specific autoimmune and systemic autoimmune rheumatic diseases (SARD), especially connective tissue diseases (CTDs). Due to the appearance of autoAb profiles in SARD patients and the complexity of the corresponding serological diagnosis, different diagnostic strategies have been suggested for appropriate autoAb testing. Thus, evolving assay techniques and the continuous discovery of novel autoantigens have greatly influenced the development of these strategies. Antinuclear antibody (ANA) analysis by indirect immunofluorescence (IIF) on tissue and later cellular substrates was one of the first tests introduced into clinical routine and is still an indispensable tool for CTD serology. Thus, screening for ANA by IIF is recommended to be followed by confirmatory testing of positive findings employing different assay techniques. Given the continuous growth in the demand for autoAb testing, IIF has been challenged as the standard method for ANA and other autoAb analyses due to lacking automation, standardization, modern data management, and human bias in IIF pattern interpretation. To address these limitations of autoAb testing, the CytoBead® technique has been introduced recently which enables automated interpretation of cell-based IIF and quantitative autoAb multiplexing by addressable microbead immunoassays in one reaction environment. Thus, autoAb screening and confirmatory testing can be combined for the first time. The present review discusses the history of autoAb assay techniques in this context and gives an overview and outlook of the recent progress in emerging technologies.

Periodontal findings in systemic lupus erythematosus patients and healthy controls

OBJECTIVES

To compare periodontal findings in systemic lupus erythematosus (SLE) patients and healthy controls, and to determine, whether there is a correlation between periodontal parameters and SLE biomarkers.

METHODS

This cross-sectional study was conducted in the Faculty of Dentistry, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia between November 2012 and February 2014. Twenty-five participants diagnosed with SLE and 50 healthy controls were selected. Periodontal assessment consisted of clinical attachment level (CAL), probing depth (PD), bleeding on probing, and plaque scores. For the SLE group, several laboratory tests were obtained, such as, white blood cell count, hemoglobin level, platelet count, anti-nuclear antibody, anti-double-stranded DNA antibody, calcium level, and vitamin D.

RESULTS

Periodontal findings in SLE patients and controls were not significantly different. The SLE patients who had no flare-ups for more than a year showed significant bleeding on probing and deeper PD compared with those who had flare-ups less than a year before starting the study. The SLE patients with arthritis symptoms showed more CAL than those without arthritis. In the SLE patients, no significant correlation was found between their periodontal findings and SLE biomarkers.

CONCLUSION

Periodontal health was not different between SLE patients and healthy controls. In SLE patients however, flare-ups and presence of arthritis had a significant relation with periodontal health.

A novel DNA/histone H4 peptide complex detects autoantibodies in systemic lupus erythematosus sera

BACKGROUND

The detection of anti-dsDNA antibodies is critical for the diagnosis and follow-up of systemic lupus erythematosus (SLE) patients. The presently available assays are characterized by a non-optimal specificity (solid phase assays) or sensitivity (Crithidia Luciliae immunofluorescence test (CLIFT)). To overcome the limits of CLIFT and solid phase chromatin assays, we explored the diagnostic potential of an assay based on plasmid DNA containing a highly bent fragment of 211 bp from Crithidia Luciliae minicircles, complexed with histone peptides.

METHODS

Electrically neutral complexes of PK201/CAT plasmid (PK) DNA and histone 4 (H4) peptides were evaluated by electromobility shift assay. Complexes of H4 peptides and PK were absorbed to the solid phase to detect specific immunoglobulin G (IgG) in sera. Sera from 109 SLE patients, 100 normal healthy subjects, and 169 disease controls were tested.

RESULTS

H4(14-34) containing the consensus sequence for DNA binding interacts with PK, retarding its migration. H4(14-34)/PK complexes were used to test sera by ELISA. Anti-H4-PK antibodies were detected in 56 % of SLE sera (more frequently in patients with skin or joint involvement) versus 5.9 % in disease controls; inhibition assays show that sera react with epitopes present on DNA or on the complex, not on the peptide. Antibody titer is correlated with European Consensus Lupus Activity Measurement (ECLAM) score and anti-complement component 1q (C1q) antibodies, negatively with C3 levels. Anti-H4-PK antibodies compared with CLIFT and solid phase dsDNA assays display moderate concordance.

CONCLUSIONS

The H4/PK assay is a simple and reliable test which is useful for the differential diagnosis and evaluation of disease activity in SLE patients.

'Atherothrombosis-associated microRNAs in Antiphospholipid syndrome and Systemic Lupus Erythematosus patients'

MicroRNAs markedly affect the immune system, and have a relevant role in CVD and autoimmune diseases. Yet, no study has analyzed their involvement in atherothrombosis related to APS and SLE patients. This study intended to: 1) identify and characterize microRNAs linked to CVD in APS and SLE; 2) assess the effects of specific autoantibodies. Six microRNAs, involved in atherothrombosis development, were quantified in purified leukocytes from 23 APS and 64 SLE patients, and 56 healthy donors. Levels of microRNAs in neutrophils were lower in APS and SLE than in healthy donors. Gene and protein expression of miRNA biogenesis-related molecules were also reduced. Accordingly, more than 75% of identified miRNAs by miRNA profiling were underexpressed. In monocytes, miR124a and -125a were low, while miR-146a and miR-155 appeared elevated. Altered microRNAs’ expression was linked to autoimmunity, thrombosis, early atherosclerosis, and oxidative stress in both pathologies. In vitro treatment of neutrophils, monocytes, and ECs with aPL-IgG or anti-dsDNA-IgG antibodies deregulated microRNAs expression, and decreased miRNA biogenesis-related proteins. Monocyte transfections with pre-miR-124a and/or -125a caused reduction in atherothrombosis-related target molecules. In conclusion, microRNA biogenesis, significantly altered in neutrophils of APS and SLE patients, is associated to their atherothrombotic status, further modulated by specific autoantibodies.

Serological profile and clinical features of nucleolar antinuclear pattern in patients with systemic lupus erythematosus from southwestern Spain

Nucleolar staining of antinuclear antibodies (ANAs) is not exclusive to patients suffering systemic sclerosis (SSc) since it can occur in other autoimmune diseases, such as systemic lupus erythematosus (SLE). The nucleolar ANA pattern presents a low incidence in patients with SLE, with less than 9% reported in some studies. The significance of nucleolar staining and antinucleolar antibodies (ANoA) in SLE is still unknown, as is its association with clinical manifestations. To address these issues, a case-control study was carried out. Twenty-eight cases of SLE with nucleolar staining were enrolled, as well as 73 controls with no nucleolar staining and different ANA patterns (homogeneous, speckled, and combined homogeneous and speckled). The homogeneous nucleolar pattern was the most frequent (27 out of 28), and in 75% was combined with other ANA patterns. The anti-double stranded DNA antibodies showed no differences between the two groups of patients, nor the auto-antibodies detected by line immunoassay (LIA). However, we have found an increased frequency of anti-PM-Scl antibodies with respect to the controls ( p = 0.02), in addition to the association between Raynaud's phenomenon (RP) and anti-PM-Scl antibodies (OR = 20.72, 95% CI 1.33–323.19, p = 0.03). Moreover, the cases of SLE showed a 7.78-fold increase in the risk of developing cancer (95%, CI 1.85–32.75, p = 0.005) with respect to the control group. Taken together these findings suggest that nucleolar staining represents a comorbidity factor in patients with SLE, although its significance must still be determined.

Biomarkers in lupus nephritis

Lupus nephritis (LN) has significant impact on the outcome of patients with systemic lupus erythematosus (SLE). In the absence of any new breakthrough for management of LN over the last few years, using existing treatment modalities in a more effective manner is the mainstay of improving outcomes. For effectively using the drugs, disease activity needs to be assessed accurately and more objectively, which is not possible with present clinical assessment tools. Biomarkers help in accurate assessment of disease activity and enable the physician to individualize the therapy. Conventional disease activity markers have limitations which need to be addressed and research in the area of biomarker discovery in LN has immensely expanded over the last two decades as evident by the literature. Moreover, biomarkers for LN should be different from the markers of overall disease activity as LN requires significant immunosuppression, unlike other non-renal manifestations of SLE. Newly discovered biomarkers exhibit qualities pertaining to different aspects of disease activity and damage. In this review, we discuss the established as well as new biomarkers of SLE in the light of their role in LN diagnosis, follow-up, prediction of renal flare and correlation with renal histology findings.

Altered glutamate cysteine ligase activity in peripheral blood mononuclear cells from patients with systemic lupus erythematosus

Reductions in glutathione (GSH) levels have been shown to be associated with aging and the pathogenesis of a variety of diseases, including systemic lupus erythematosus (SLE). Glutamate cysteine ligase (GCL) catalyzes the first and rate-limiting step of GSH synthesis. In order to appraise the correlation between oxidative stress and the severity and activity of SLE, GSH, oxidized GSH (GSSG) and thioredoxin (TRX) concentrations and the enzymatic activity levels of GCL in peripheral blood mononuclear cells (PBMCs) from patients with SLE and healthy controls were studied. In patients with SLE, the levels of GCL activity and GSH decreased, while TRX and GSSG levels increased when compared with those in the healthy controls. GSH concentrations and GCL activity levels negatively correlated with the SLE disease activity index and erythrocyte sedimentation rate. Furthermore, patients with SLE and nephritis had lower levels of GSH and GCL activity and higher levels of TRX and GSSG compared with those in SLE patients without nephritis. Therefore, the results of the present study indicate that insufficient levels of GSH and GCL activity in PBMCs may contribute to the pathogenesis of SLE.

The spectrum of anti-chromatin/nucleosome autoantibodies: independent and interdependent biomarkers of disease

Autoantibodies directed to chromatin components date back to the discovery of the LE cell and the LE cell phenomenon circa 1950, and subsequent evidence that major components of that reaction were chromatin components and histones in particular. Over time, immunoassays ranging from ELISA and line immunoassays to more modern bead-based assays incorporated histone and DNA mixtures, purified histones, and purified nucleosomes leading to a more thorough understanding of the genesis and pathogenetic relationships of antibodies to chromatin components in systemic lupus erythematosus and other autoimmune conditions. More recently, interest has focussed on other components of chromatin such as high mobility group (HMG) proteins both as targets of B cell responses and pro-inflammatory mediators. This review will focus on immunoassays that utilize chromatin components, their clinical relationships, and newer evidence implicating HMG proteins and DNA neutrophil extracellular traps (NETs) as important players in systemic autoimmune rheumatic diseases.

Standardization of autoantibody testing: a paradigm for serology in rheumatic diseases

Autoantibody measurement is an excellent tool to confirm the diagnosis of rheumatic autoimmune diseases. Hence, reliability and harmonization of autoantibody testing are essential, but these issues are still a matter of debate. Intrinsic variability in analytes and reagents as well as heterogeneity of the techniques are the main reasons for discrepancies in inter-laboratory variations and reporting of test results. This lack of reliability might be responsible for wrong or missed diagnoses, as well as additional costs due to assay repetition, unnecessary use of confirmatory tests and/or consequent diagnostic investigations. To overcome such issues, the standardization of autoantibody testing requires efforts on all aspects of the assays, including the definition of the analyte, the pre-analytical stages, the calibration method and the reporting of results. As part of such efforts, the availability of suitable reference materials for calibration and quality control would enable the development of a reliable reference system. Strong-positive sera from patients have been used as reference materials in most of the autoantibody assays for rheumatic diseases; however, antigen-affinity-purified immunoglobulin fractions or in some cases reliable monoclonal antibody preparations offer more adequate tools for standardization. Systematic assessments of reference materials are currently underway, and preliminary results appear to be encouraging.

Concomitance of IgM and IgG anti-dsDNA Antibodies Does Not Appear to Associate to Active Lupus Nephritis

Previous reports proposed that the IgM anti-dsDNA antibody is protective for lupus nephritis. In this cross-sectional study, we aimed to compare clinical features of systemic lupus erythematosus (SLE) patients positive for IgG anti-dsDNA alone with those presenting both IgG and IgM anti-dsDNA. Anti-dsDNA antibodies, urinary examination and complement levels were assessed in the day of appointment. IgG and IgM anti-dsDNA antibodies were detected by indirect immunofluorescence. Fifty-eight SLE patients (93.1% female, 81% European-derived, mean age 42.8±14.7 years, mean duration of disease 10.9±8 years) positive for IgG anti-dsDNA entered the study. Of those, 15 were also positive for the IgM anti-dsDNA isotype. The group with both isotypes showed significant less frequency of active nephritis (sediment changes and proteinuria) when compared to patients with IgG anti-dsDNA alone (6.7% versus 34.9%, p=0.046). These data suggest a nephroprotective role for IgM anti-dsDNA and a distinct biologic behavior for this isotype in SLE.

Elevated subclinical double-stranded DNA antibodies and future proliferative lupus nephritis

BACKGROUND AND OBJECTIVES

Elevated anti-double-stranded DNA (dsDNA) antibody and C-reactive protein are associated with proliferative lupus nephritis (PLN). Progression of quantitative anti-dsDNA antibody in patients with PLN has not been compared with that in patients with systemic lupus erythematosus (SLE) without LN before diagnosis. The temporal relationship between anti-dsDNA antibody and C-reactive protein elevation has also not been evaluated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This case-control Department of Defense Serum Repository (established in 1985) study compared longitudinal prediagnostic quantitative anti-dsDNA antibody and C-reactive protein levels in 23 patients with biopsy-proven PLN (Walter Reed Army Medical Center, 1993-2009) with levels in 21 controls with SLE but without LN matched for patient age, sex, race, and age of serum sample. The oldest (median, 2601 days; 25%, 1245 days, 75%, 3075 days), the second to last (368; 212, 635 days), and the last (180; 135, 477 days) serum sample before diagnosis were analyzed.

RESULTS

More patients with PLN had an elevated anti-dsDNA antibody level than did the matched controls at any point (78% versus 5%; P<0.001), <1 year (82% versus 8%; P<0.001), 1-4 years (53% versus 0%; P<0.001), and >4 years (33% versus 0%; P=0.04) before diagnosis. A rate of increase >1 IU/ml per year (70% versus 0%; P<0.001) was most specific for PLN. The anti-dsDNA antibody levels increased before C-reactive protein did in most patients with an antecedent elevation (92% versus 8%; P<0.001).

CONCLUSIONS

Elevated anti-dsDNA antibody usually precedes both clinical and subclinical evidence of proliferative LN, which suggests direct pathogenicity. Absolute anti-dsDNA antibody level and rate of increase could better establish risk of future PLN in patients with SLE.

A colorimetric method for protein assay via exonuclease III-assisted signal attenuation strategy and specific DNA-protein interaction

Taking advantage of exonuclease III (Exo III)-assisted signal attenuation strategy and the protection of DNA from Exo III-mediated digestion by specific DNA-protein interaction, a colorimetric method is proposed in this paper for protein assay. Specifically, in the absence of target protein, Exo III-assisted signal attenuation can be achieved by digesting the report DNA in a complex formed by the hybridization of a report DNA and a probe DNA. Nevertheless, in the presence of target protein, the binding of the analyte to the probe DNA will inhibit the Exo III-assisted nucleotides cleavage, so that cyclic signal attenuation is blocked. Therefore, a bridge can be established between the concentration of target protein and the degree of the attenuation of the obtained signal, and the relationship can be shown by the surface plasmon changes caused by the report DNA-induced aggregation of DNA-modified gold nanoparticles (AuNPs). Our method can also have considerable sensitivity and selectivity, which has been demonstrated by the assay of human α-thrombin. Furthermore, by simply changing the sequence of the probe DNA, we can expand the application of our method to not only aptamer binding proteins but also DNA binding proteins, thus we have also used this method to analyze a specific serological marker for systemic lupus erythematosus (SLE) in this study. With a broad detection range of 1.3-133 nM and a detection limit of 0.61 nM (S/N=3), it may hold great promise for clinical application.

Lipid anti-lipid antibody responses correlate with disease activity in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by broad clinical manifestations including cardiovascular and renal complications with periodic disease flares and significant morbidity and mortality. One of the main contributing factors to the pathology of SLE is the accumulation and impaired clearance of immune complexes of which the principle components are host auto-antigens and antibodies. The contribution of host lipids to the formation of these autoimmune complexes remains poorly defined. The aim of the present study was to identify and analyze candidate lipid autoantigens and their corresponding anti-lipid antibody responses in a well-defined SLE patient cohort using a combination of immunological and biophysical techniques. Disease monitoring in the SLE cohort was undertaken with serial British Isles Lupus Assessment Group (BILAG) scoring. Correlations between specific lipid/anti-lipid responses were investigated as disease activity developed from active flares to quiescent during a follow up period. We report a significant negative correlation between anti-lipid antibodies for 24S-hydroxycholesterol, cardiolipin and phosphatidylserine with SLE disease activity. Taken together, these data suggest that lipid autoantigens represent a new family of biomarkers that can be employed to monitor disease activity plus the efficacy of therapeutic intervention in SLE.

Self double-stranded (ds)DNA induces IL-1β production from human monocytes by activating NLRP3 inflammasome in the presence of anti-dsDNA antibodies

The pathogenic hallmark of systemic lupus erythematosus is the autoimmune response against self nuclear Ags, including dsDNA. The increased expression of the proinflammatory cytokine IL-1β has been found in the cutaneous lesion and PBMCs from lupus patients, suggesting a potential involvement of this cytokine in the pathogenesis of lupus. IL-1β is produced primarily by innate immune cells such as monocytes and can promote a Th17 cell response, which is increased in lupus. IL-1β production requires cleaving pro-IL-β into IL-1β by the caspase-1-associated multiprotein complex called inflammasomes. In this study we show that self dsDNA induces IL-1β production from human monocytes dependent on serum or purified IgG containing anti-dsDNA Abs by activating the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Reactive oxygen species (ROS) and K(+) efflux were involved in this activation. Knocking down the NLRP3 or inhibiting caspase-1, ROS, and K(+) efflux decreased IL-1β production. Supernatants from monocytes treated with a combination of self dsDNA and anti-dsDNA Ab(+) serum promoted IL-17 production from CD4(+) T cells in an IL-1β-dependent manner. These findings provide new insights in lupus pathogenesis by demonstrating that self dsDNA together with its autoantibodies induces IL-1β production from human monocytes by activating the NLRP3 inflammasome through inducing ROS synthesis and K(+) efflux, leading to the increased Th17 cell response.

Circulating anti-double-stranded DNA antibody-secreting cells in patients with systemic lupus erythematosus: a novel biomarker for disease activity

Antibodies against double-stranded DNA (dsDNA) are widely used to diagnose systemic lupus erythematosus (SLE) and evaluate its activity in patients. This study was undertaken to examine the clinical utility of circulating anti-dsDNA antibody-secreting cells for evaluating SLE patients. Anti-dsDNA antibody-secreting cells quantified using an enzyme-linked immunospot assay were detected in the spleen, bone marrow and peripheral blood from MRL/ lpr but not in control BALB/c mice. Circulating anti-dsDNA antibody-secreting cells were detected in 29 (22%) of 130 patients with SLE, but in none of 49 with non-SLE connective-tissue disease or 18 healthy controls. The presence of circulating anti-dsDNA antibody-secreting cells was associated with persistent proteinuria, high SLE disease activity index and systemic lupus activity measures, and a high serum anti-dsDNA antibody titre measured with an enzyme-linked immunosorbent assay. The positive predictive value for active disease was 48% for circulating anti-dsDNA antibody-secreting cells versus 17% for serum anti-dsDNA antibodies. A prospective cohort of patients with circulating anti-dsDNA antibodies and inactive SLE showed that the cumulative disease flare-free rate was significantly lower in patients with than without circulating anti-dsDNA antibody-secreting cells ( p < 0.001). Circulating anti-dsDNA antibody-secreting cells are a useful biomarker for assessing disease activity in SLE patients.

Transgenic overexpression of anti-double-stranded DNA autoantibody and activation of Toll-like receptor 4 in mice induce severe systemic lupus erythematosus syndromes

Systemic lupus erythematosus (SLE) is a multi-organ autoimmune disease characteristized by the presence of autoantibodies against double-stranded DNA (anti-dsDNA) in sera at high levels. Bacterial infections in SLE are associated with higher morbidity and mortality. Our goal was to observe the interaction between these 2 factors in the pathogenesis of lupus. We generated transgenic mice with monoclonal anti-dsDNA to investigate the development of lupus. By challenging the mice in vitro and in vivo with Toll-like receptor 4 (TLR4) ligand lipopolysaccharides (LPS), we were able to examine the role of bacterial infection in SLE. In our study, the transgenic mice with a secreted form of anti-dsDNA were found to have higher levels of anti-nuclear antibodies, anti-dsDNA, blood urea nitrogen, and proteinuria. The splenocytes of the mice stimulated with LPS secreted more anti-dsDNA, IFN-γ, and IL-10. After injecting them with LPS in vivo, we further found higher immune complex depositions and IL-10 in the kidneys of the transgenic mice. Moreover, the LPS-injected transgenic mice had higher mortality rate. This is the first transgenic model to demonstrate that only 2 risk factors, pathogenic anti-dsDNA and TLR4 activation, induce severe SLE syndromes in normal mice through the overproduction of IL-10 and IFN-γ. These findings imply that anti-dsDNA and bacterial infections have pivotal roles in the pathogenesis of SLE; the inhibition of TLR4 may be regarded as a therapeutic target.

Autoantibodies to double-stranded DNA-Intermethod comparison between four commercial immunoassays and a research biosensor-based device

Patients with systemic lupus erythematosus (SLE) often develop a wide variety of serological manifestations including the presence of antibodies to double-stranded DNA (anti-dsDNA). Positivity for anti-dsDNA constitutes one of the laboratory criteria for the diagnosis of SLE and is therefore clinically relevant. We analyzed the diagnostic accuracies of four commercial anti-dsDNA immunoassays and compared the results with a recently established surface plasmon resonance (SPR) biosensor chip with covalently chip-immobilized dsDNA. The anti-dsDNA measurements were performed retrospectively in 50 patients with clinically proven SLE, 39 patients with other autoimmunopathies and 20 healthy controls. Data were evaluated by Receiver-Operator Characteristic (ROC) analysis, with special regard to SLE patients suffering from lupus nephritis. The ROC analyses for the four immunoassays and the SPR biosensor resulted in the following area-under-the-curve (AUC) and diagnostic efficiency (DE) values in descending order: Bindazyme AUC, 0.89; DE, 0.88; ELiA AUC, 0.89; DE, 0.86; SPR biosensor AUC, 0.82; DE, 0.80; Farrzyme AUC, 0.77; DE, 0.77; Farr AUC, 0.77; DE, 0.70. When considering the 22 nephritis SLE patients the following AUC were observed: Bindazyme 0.98; EliA 0.95; SPR biosensor 0.93; Farr 0.89; Farrzyme 0.88. Although various methodologies for the determination of anti-dsDNA were compared, the overall diagnostic accuracy was found satisfactory in all immunoassays. Best data were found for the Bindazyme assay. We referenced the measurements to our in-house SPR biosensor device which showed good AUC and DE values. When optimized, this technique, allowing to monitor antigen/ antibody interactions in real-time, may add a new analytical quality to the existing methods, potentially beneficial in diagnosis and clinical monitoring of SLE.

Quantitative, reagentless, single-step electrochemical detection of anti-DNA antibodies directly in blood serum

Here we demonstrate the use of redox labeled double- and single-stranded oligonucleotides as recognition probes for the reagentless, single-step, electrochemical detection of anti-DNA antibodies directly in blood serum.

Differential responses to Smith D autoantigen by mice with HLA-DR and HLA-DQ transgenes: dominant responses by HLA-DR3 transgenic mice with diversification of autoantibodies to small nuclear ribonucleoprotein, double-stranded DNA, and nuclear antigens

Anti-Smith (Sm) D autoantibodies are specific for systemic lupus erythematosus. In this investigation, the influence of HLA-D genes on immune responses to SmD was investigated. Mice with HLA-DR3, HLA-DR4, HLA-DQ0601, HLA-DQ0604, or HLA-DQ8 transgenes were immunized with recombinant SmD1, and their Ab responses were analyzed. Analysis by ELISA showed that all strains responded well to SmD. However, when synthetic SmD peptides were used as substrate, DR3 mice had the highest Ab response followed by DQ8, DQ0604, DQ0601, and DR4. A similar trend was observed in Western blot analysis using WEHI 7.1 cell lysate as the substrate, with the exception that DR4 mice did not generate detectable amounts of Abs. Only sera from DR3 and DQ0604 mice immunoprecipitated A-ribonucleoprotein (RNP), SmB, and SmD. Intermolecular epitope spreading to A-RNP and SmB was evident in DR3 and DQ0604 mice, as sera depleted of anti-SmD Abs were reactive with these proteins. DR3 mice also generated an immune response to C-RNP. Anti-nuclear Abs were detected in the majority of the DR3 mice, whereas moderate reactivities were seen in DQ0604 and DQ8 mice. Interestingly, only DR3 mice mounted an anti-dsDNA Ab response. Approximately half of the anti-dsDNA Abs were cross-reactive with SmD. Ab responses correlated with the strength of the T cell responses. Thus, HLA-DR3 appears to be the dominant HLA-D gene that determines the magnitude and quality of the anti-SmD immune response. In addition, our findings provide insights into the origin of the anti-dsDNA Abs often detected in patients with systemic lupus erythematosus.

Correlation between clinical activity and serological markers in a wide cohort of patients with systemic lupus erythematosus: an eight-year prospective study

Titers of serum anti-double-stranded DNA antibodies (anti-dsDNA Abs) and C3 and C4 are used for monitoring systematic lupus erythematosus (SLE) patients. Here, we assessed the relationship between the clinical activity index (SLEDAI) and serum titers of anti-dsDNA Abs, C3, and C4 in an 8-year prospective study conducted in 194 SLE patients. The association of anti-dsDNA Abs and complement with M-SLEDAI was significant but low. Ninety-eight of the 194 patients were selected because they were followed for at least 5 years. We observed four types of clinical-serological patterns: parallelism between serum and clinical activity (n = 24), clinical quiescence with partial serum activity (n = 30), clinical quiescence but serologically fully active (n = 18), and clinical activity but serologically quiescent (n = 21). The serological markers evaluated are of limited utility in the monitoring of SLE patients and their use must be individualized.

Development and validation of a fluorescent microsphere immunoassay for soluble CD30 testing

Testing for soluble CD30 (sCD30), an indicator of Th2 immune response, is a useful prognostic marker in solid organ transplantation, lymphoproliferative disorders, autoimmunity, and various parasitic diseases. In this study we report the development and validation of a fluorescent microsphere immunoassay for the detection of sCD30 in serum, plasma, and culture supernatants. The dynamic range of this assay is 1 to 400 ng/ml, and the rate of recovery of various concentrations of recombinant sCD30 ranges from 97 to 116% (average recovery, 105%). The test showed a high degree of precision in both intra-assay and interassay studies (coefficients of variation, as high as 7% and 8%, respectively), with a sensitivity of 1 ng/ml. The normal reference range calculated for a cohort of 151 healthy individuals was 1 to 29 ng/ml. The clinical usefulness of the sCD30 fluorescent microsphere immunoassay was demonstrated by showing that levels of sCD30 have a positive correlation with specimens containing high titers of anti-double-stranded DNA antibodies and high titers of immunoglobulin G against Leishmania species. Given the multiplexing potential of the sCD30 fluorescent microsphere immunoassay reported in this study, it is expected that testing of sCD30 concentrations along with those of other cytokines will become an important diagnostic tool for selected immunological and inflammatory diseases where Th2-type cytokine responses have been reported.

Incidence and nature of infectious disease in patients treated with anti-TNF agents

Tumor necrosis factor alpha (TNF-alpha) inhibitors offer a targeted therapeutic strategy that contrasts with the nonspecific immunosuppressive agents traditionally used to treat most inflammatory diseases. These biologic agents have had a significant impact in ameliorating the signs and symptoms of inflammatory rheumatoid disease and improving patient function. From the onset of clinical trials, a central concern of cytokine blockade has been a potential increase in susceptibility to infections. Not surprisingly, a variety of infections have been reported in association with the use of TNF-alpha inhibitor agents. In particular, there is evidence suggesting an increased rate of granulomatous infections in patients treated with monoclonal TNF-alpha inhibitors. This review provides the incidence and nature of infections in patients treated with TNF-alpha inhibitor agents and reminds the clinician of the required vigilance in monitoring patients.