A critical view on autoantibodies in lupus nephritis: Concrete knowledge based on evidence

Deposition of autoantibodies in glomeruli is a key factor in the development of lupus nephritis (LN). For a long time, anti-dsDNA and anti-C1q antibodies were thought to be the main cause of the kidney damage. However, recent studies have shown that the list of autoantibidies that have renal tropism and deposit in the kidney in LN is increasing and the link between anti-dsDNA and renal pathology is weak due to potential confounders. Aspecific bindings of dsDNA with cationic antibodies and of anti-dsDNA with several renal antigens such as actinin, laminin, entactin, and annexinA2 raised doubts about the specific target of these antibodies in the kidney. Moreover, the isotype of anti-dsDNA in SLE and LN has never received adequate interest until the recent observation that IgG2 are preponderant over IgG1, IgG3 and IgG4. Based on the above background, recent studies investigated the involvement of anti-dsDNA IgG2 and of other antibodies in LN. It was concluded that circulating anti-dsDNA IgG2 levels do not distinguish between LN versus non-renal SLE, and, in patients with LN, their levels do not change over time. Circulating levels of other antibodies such as anti-ENO1 and anti-H2 IgG2 were, instead, higher in LN vs non-renal SLE at the time of diagnosis and decreased following therapies. Finally, new classes of renal antibodies that potentially modify the anti-inflammatory response in the kidney are emerging as new co-actors in the pathogenetic scenario. They have been defined as 'second wave antibodies' for the link with detoxifying mechanisms limiting the oxidative stress in glomeruli that are classically stimulated in a second phase of inflammation. These findings have important clinical implications that may modify the laboratory approach to LN. Serum levels of anti-ENO1 and anti-H2 IgG2 should be measured in the follow up of patients for designing the length of therapies and identify those patients who respond to treatments. Anti-SOD2 could help to monitor and potentiate the anti-inflammatory response in the kidney.

Correlation Between Quantitative Anti-dsDNA Levels with Severity of Proteinuria in Systemic Lupus Erythematosus Patients

OBJECTIVE

To evaluate the correlation of quantitative anti-dsDNA level with proteinuria levels in patients with lupus nephritis in a tertiary care hospital.

STUDY DESIGN

In this prospective cross-sectional study, 76 patients of newly diagnosed SLE coming to Fatima Memorial Hospital were included in the study period between January 2020 to June 2020. Demographic data such as age, gender, lupus manifestations such as serositis, arthritis, mucocutaneous disease, and neuropsychiatric manifestations were recorded. Quantitative anti-dsDNA was measured by enzyme-linked immunosorbent assay and proteinuria was estimated by 24h urinary protein collection. Data was analyzed by SPSS 23. Association between categorical variables was assessed using chi-square test. For comparison of categorical independent and continuous dependent variable t-test or Mann-Whitney U test was applied.

RESULTS

The median age of the cohort was 29 (with inter quartile range - IQR - of 13) years. The female gender comprised of 68 (89.4%) of the cohort population. The median anti-dsDNA level was 54.9 (183.6 IQR) IU, and baseline proteinuria of the cohort was 520mg/dL (1.49 IQR). There was a significant association of anti-dsDNA level with systemic features such as arthritis (p=<0.01), serositis (p=<0.01) and, Raynaud's phenomenon (p=<0.01). NPSLE and mucocutaneous features did not show statistically significant association (p=0.91 and 0.14 respectively). Baseline anti-dsDNA showed a statistically significant correlation with baseline proteinuria levels (p=<0.01).

CONCLUSION

Quantitative anti-dsDNA is directly correlated with nephritis measured as proteinuria, and can be detected even before organ involvement. Hence, it can determine disease course and guide early treatment.

Safety and efficacy of belimumab after B cell depletion therapy in systemic LUPUS erythematosus (BEAT-LUPUS) trial: statistical analysis plan

Background

There is limited evidence that rituximab, a B cell depletion therapy, is an effective treatment for systemic lupus erythematosus (SLE). Data on the mechanisms of B cell depletion in SLE indicate that the combination of rituximab and belimumab may be more effective than rituximab alone. The safety and efficacy of belimumab after B cell depletion therapy in systemic LUPUS erythematosus (BEAT-LUPUS) trial aims to determine whether belimumab is superior to placebo, when given 4–8 weeks after treatment with rituximab. This article describes the statistical analysis plan for this trial as an update to the published protocol. It is written prior to the end of patient follow-up, while the outcome of the trial is still unknown.

Design and methods

BEAT-LUPUS is a randomised, double-blind, phase II trial of 52 weeks of belimumab versus placebo, initiated 4–8 weeks after rituximab treatment. The primary outcome is anti-dsDNA antibodies at 52 weeks post randomisation. Secondary outcomes include lupus flares and damage, adverse events, doses of concomitant medications, quality of life, and clinical biomarkers. We describe the trial’s clinical context, outcome measures, sample size calculation, and statistical modelling strategy, and the supportive analyses planned to evaluate for mediation of the treatment effect through changes in concomitant medication doses and bias from missing data.

Discussion

The analysis will provide detailed information on the safety and effectiveness of belimumab. It will be implemented from July 2020 when patient follow-up and data collection is complete.

Trial registration

ISRCTN: 47873003. Registered on 28 November 2016.

EudracT: 2015-005543-14. Registered on 19 November 2018.

Influence of air pollution on renal activity in patients with childhood-onset systemic lupus erythematosus

BACKGROUND

Childhood-onset systemic lupus erythematosus (cSLE) is an autoimmune and multifactorial disease that can affect the renal system. Exposure to air pollution can trigger systemic inflammation in cSLE patients and increase risk of disease activity. We evaluated effects of individual real-time exposure to air pollutants on renal activity in cSLE patients using the Systemic Lupus Erythematosus Disease Activity Index 2000.

METHODS

Longitudinal panel study of 108 repetitive measures from 9 pediatric lupus patients. Over three consecutive weeks, daily individual levels of fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) were measured, as well as weekly clinical evaluation and laboratory tests. This was repeated every 10 weeks over a 1-year period. Specific generalized estimating equation models were used to evaluate the impact of these pollutants on risk of nephritis and anti-dsDNA > 20 UI/mL and on 24-h urine protein and serum complement (C3) levels.

RESULTS

An interquartile range (IQR) increase of 18.12 μg/m³ in PM_2.5 daily concentration was associated with increased risk of nephritis and positive results for anti-dsDNA. Moreover, increase in 24-h urine protein and decrease in C3 serum levels also associated with exposure to pollutants. An IQR increase in PM_2.57-day moving average was associated with increased risks of leukocyturia (3.4; 95% CI 2.6:4.3), positive anti-dsDNA (3.1; 95% CI 2.1:4.0), and 36.3-mg increase (95% IC 20.2:52.3) in 24-h urine protein. An IQR increase (63.1 μg/m³) in 7-day cumulative NO₂ levels was associated with decreased serum C3 levels.

CONCLUSIONS

This prospective study suggests exposure to air pollution can trigger renal activity in cSLE patients.

Neutrophil extracellular traps-associated markers are elevated in patients with systemic lupus erythematosus

Neutrophil extracellular traps (NETs) are the main source of autoantigens in systemic lupus erythematosus (SLE). The aim of this study was to evaluate the clinical importance of NETs-associated markers in SLE. We compared NETs-associated markers in SLE patients (n = 111) with healthy controls (n = 50). Moreover, in 35 patients with drug-naïve SLE (n = 35), we investigated correlation between NETs-associated markers [DNase I concentration, myeloperoxidase (MPO) activity, anti-MPO antibodies, cell-free DNA (cfDNA), NETolytic activity] with serological parameters [anti-dsDNA antibodies, C3, C4 and B-cell activating factor (BAFF) levels] and disease activity measured by modified SLE Disease Activity Index (M-SLEDAI-2K). In comparison with healthy controls, SLE patients had higher cfDNA, MPO activity, anti-MPO antibodies (p < 0.001), BAFF and DNase I concentration (p < 0.01). Contrary, NETolytic activity was lower in SLE patients (p < 0.05), despite higher concentration of DNase I. MPO activity and cfDNA levels showed correlation with DNase I concentration (p < 0.001, p < 0.01, respectively). BAFF levels correlated with cfDNA, DNase I concentration and MPO activity (p < 0.05). Anti-dsDNA antibodies showed correlation with MPO activity (p < 0.01), cfDNA and BAFF levels (p < 0.001). Anti-dsDNA and C3 levels were independent predictors of M-SLEDAI-2K in multivariate analysis (p < 0.01). We demonstrated that sera of SLE patients have decreased NETolytic activity, leading to increased levels of various NETs-associated markers, which correlate with anti-dsDNA antibodies in drug-naïve SLE. We showed that BAFF participates in a complex relationship between NETosis and anti-dsDNA antibodies production. These findings have important implications for a better understanding of SLE pathogenesis and development of therapy that inhibits NETs persistence and disease progression.

Detection of DNA Autoantibodies by Electrophoretic Mobility Shift Assay

Although the presence of antibodies against double-stranded (ds) DNA is considered the serological hallmark of systemic lupus erythematosus (SLE), it is not detected in all SLE patients by routine laboratory tests. Looking at DNA-anti(ds)DNA interaction as one kind of DNA-protein interaction gave us the grounds for a novel type of assay, easy to perform, and providing a direct insight on DNA-anti(ds)DNA IgG interaction. The assay is an application of the electrophoretic mobility shift assay (EMSA) and is based on the observation that the electrophoretic mobility of a DNA-protein complex is typically less than that of free DNA. The EMSA, performed here with purified bacterial DNA and the purified IgG fraction of sera from systemic lupus erythematosus (SLE) or other patients as well as from healthy individuals, revealed itself to be more sensitive than the routinely used assays for the detection of anti-dsDNA in SLE and discoid lupus erythematosus (DLE) patients. In addition, besides providing a direct visualization of DNA-anti(ds)DNA IgG complexes, the assay offers the possibility to study in detail the nature of DNA-IgG interactions. In a further development, we showed that the assay could be performed successfully with sera.

The Potent Inhibitory Effect of β-D-Mannuronic Acid (M2000) as a Novel NSAID with Immunosuppressive Property on Anti-Cyclic Citrullinated Peptide Antibodies, Rheumatoid Factor and Anti-dsDNA Antibodies in Patients with Rheumatoid Arthritis

OBJECTIVE

To investigate the inhibitory effect of β-D-mannuronic acid (M2000) on anti-cyclic citrullinated peptide antibodies (anti-CCP), rheumatoid factor (RF), antidouble strand DNA (anti-dsDNA) and acute phase reactants in rheumatoid arthritis (RA) patients.

METHODS

The study included 40 patients with RA who had an inadequate response to conventional therapy (identifier: IRCT2014011213739N2). The patients were permitted to continue the conventional therapy excluding NSAIDs. 21 of them were treated orally by M2000 at a dose of 500 mg twice daily for 12 weeks and the others did not. Serum samples were collected at baseline, 4 weeks and 12 weeks after treatment and were tested for the serum level of anti-CCP and anti-dsDNA antibodies using enzyme linked immunosorbent assay. The serum level of RF and C-reactive proteins (CRP) was determined by the immunoturbidimetric assay, respectively.

RESULTS

At baseline, all patients in the M2000 treated group and the control group were positive for anti-CCP, RF. moreover, 4 of 21 (19%) in the M2000 treated group and 2 of the 19 (10.5%) patients in the control group were positive for anti-dsDNA antibodies, respectively. The serum levels of anti-CCP, RF and anti-dsDNA were decreased significantly after M2000 therapy (p<0.001, p<0.001 and p<0.001, respectively). The reduction in the level of anti-CCP was positively correlated with disease activity, swollen joint count and CRP. Furthermore, the level of inflammatory markers ESR and CRP decreased significantly after M2000 therapy (p<0.001 and p<0.004, respectively).

CONCLUSION

M2000 shows inhibitory effect on anti-CCP, RF, anti-dsDNA antibodies and acute phase reactants in RA patients.

Adult Onset Still's Disease With Different Antibodies: A Case Report and Review of Literature

 Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder of unknown etiology. There is not currently any specific serological markers for AOSD , and  diagnosis still relying on the exclusion of other likely diagnoses. Yamaguchi's criteria are used as a diagnostic criterion which contains negative serologic markers for other collagen vascular diseases including systemic lupus erythematosus and rheumatoid arthritis. Here we report a 28-year-old woman with arthralgia, fever, rash, leukocytosis, lymphadenopathy, sore throat, abnormal liver function and negative rheumatoid factor and ANA but  seropositive for anti-CCP, anti-dsDNA, and C-ANCA. It seems that despite AOSD is considered as a seronegativedisorder; it should be remembered in patients with compatible findings who are seropositive.

Reactivity in ELISA with DNA-loaded nucleosomes in patients with proliferative lupus nephritis

Autoantibodies against nucleosomes are considered a hallmark of systemic lupus erythematosus (SLE). We compared in patients with proliferative lupus nephritis the diagnostic usefulness of a dsDNA-loaded nucleosome ELISA (anti-dsDNA-NcX) with ELISAs in which dsDNA or nucleosomes alone were coated. First, we analysed whether DNA loading on nucleosomes led to masking of epitopes by using defined monoclonal anti-DNA, anti-histone and nucleosome-specific autoantibodies to evaluate the accessibility of nucleosomal epitopes in the anti-dsDNA-NcX ELISA. Second, autoantibody levels were measured in these 3 ELISAs in 100 patients with proliferative lupus nephritis (LN) before immunosuppressive treatment and in 128 non-SLE disease controls. In patients with LN inter-assay comparisons and associations with clinical and serological parameters were analysed. The panel of monoclonal antibodies revealed that all epitopes were equally accessible in the anti-dsDNA-NcX ELISA as in the two other ELISAs. Patients with proliferative lupus nephritis were positive with dsDNA-loaded nucleosomes in 86%, with DNA in 66% and with nucleosomes in 85%. In the non-lupus disease control group these frequencies were 1.6% (2 out of 128) for both the anti-dsDNA-NcX and the anti-dsDNA ELISA and 0% in the anti-nucleosome ELISA. The levels in the anti-dsDNA-NcX ELISA were high in a group of patients with LN that showed absent reactivity in the anti-DNA or low levels in the anti-nucleosome ELISA. Anti-dsDNA-NcX positivity was associated with higher SLEDAI scores within this group. Within nucleosome-based ELISAs, we propose the anti-dsDNA-NcX ELISA as the preferred test system.

Aberrant levels of natural IgM antibodies in osteoarthritis and rheumatoid arthritis patients in comparison to healthy controls

Natural IgM antibodies (nIgM) are polyreactive autoantibodies that have diverse roles in regulating autoimmunity, systemic inflammation and removal of oxidized low-density lipoproteins (oxLDL). We hypothesized that aberrant states of nIgM may exist in persons with osteoarthritis (OA) and rheumatoid arthritis (RA). Herein, we characterized and compared the levels of nIgM specific for phosphorylcholine (anti-PC), double-stranded DNA (anti-dsDNA), and galactosyl (anti-Gal) in persons with OA, RA and healthy controls (HC). Levels of anti-PC nIgM in OA patients were significantly lower than both HC and RA patients in an age-adjusted analysis (P<0.05). In contrast, anti-Gal nIgM levels were significantly higher in RA patients than OA patients (P<0.05) and markedly increased in comparison to HC. Anti-PC nIgM significantly correlated with anti-dsDNA and anti-Gal nIgM levels in HC and RA (P<0.05) but not in OA patients. Elevated CRP levels were associated with RA conditions and old ages in general. There was no significant correlation between anti-PC nIgM and CRP or oxLDL levels. Our study highlights for the first time the evidence of aberrant state of nIgM in human OA compared to healthy individuals that implicates a deficiency in immune responses to oxLDL which may contribute to the metabolic syndromes in the development of OA.

Correlation between Systemic Lupus Erythematosus Disease Activity Index, C3, C4 and Anti-dsDNA Antibodies

BACKGROUND

Therapeutic decisions in systemic lupus erythematosus (SLE) are based on the disease activity and nature of organ involvement. There are various clinical and laboratory methods to assess the lupus flares.

METHODS

Fifty one SLE patients with active disease (lupus flare) were studied. Systemic lupus erythematosus disease activity index (SLEDAI), C3, C4 and anti-double stranded DNA levels were estimated and repeated monthly till remission. After remission these tests were done three monthly. Values of serological parameters were then correlated with SLEDAI score.

RESULT

Thirteen (25.4%) patients had predominantly renal involvement while 38 (74.6%) patients had non-renal affliction. Musculoskeletal and mucocutaneous symptoms were the commonest features of lupus flare (90%). It was observed that 12 out of 13 (92.3%) patients with active renal involvement had low C3 levels and 11 (84.6%) had low C4 levels. The anti-dsDNA levels were elevated in all patients with predominant renal flare. In non-renal flare anti-dsDNA titre was raised only in 35% cases. Low C3 and C4 levels were noticed in 43% and 53% of non-renal flares respectively. Significant positive correlation was noticed between SLEDAI score and anti-dsDNA levels (0.01 level two-tailed prediction) and a significant negative correlation was observed with SLEDAI and C3, C4 levels (0.01 and 0.05 levels, two-tailed prediction) in our patients. On subgroup analysis it was noticed that this correlation is stronger for renal lupus. Negative correlation of SLEDAI and complement levels was not observed in non-renal flares.

CONCLUSION

Calculation of SLEDAI is a vital clinical tool for assessment of SLE patients. Serial estimation of anti-dsDNA titre, C3 and C4 levels help us diagnose lupus flare and make appropriate therapeutic decisions in patients with high SLEDAI score.

Early diagnosis of systemic lupus erythmatosus using ANN models of dsDNA binding antibody sequence data

In this paper a new method based on artificial neural networks (ANN), is introduced for identifying pathogenic antibodies in Systemic Lupus Erythmatosus (SLE). dsDNA binding antibodies have been implicated in the pathogenesis of this autoimmune disease. In order to identify these dsDNA binding antibodies, the protein sequences of 42 dsDNA binding and 608 non-dsDNA binding antibodies were extracted from Kabat database and encoded using a physicochemical property of their amino acids namely Hydrophilicity. Encoded antibodies were used as the training patterns of a general regression neural network (GRNN). Simulation results show that the accuracy of proposed method in recognizing dsDNA binding antibodies is 83.2%. We have also investigated the roles of the light and heavy chains of anti-dsDNA antibodies in binding to DNA. Simulation results concur with the published experimental findings that in binding to DNA, the heavy chain of anti-dsDNA is more important than their light chain.