Comparison of antibody assays for detection of autoantibodies to Ro 52, Ro 60 and La associated with primary Sjögren's syndrome

Manifestations and management of Sjögren's disease

Sjögren's disease is a heterogeneous autoimmune disorder that may be associated with systemic manifestations such as pulmonary or articular involvement. Systemic complications have prognostic implications and need to be identified and managed in a timely manner. Treatment should be tailored to the type and severity of organ involvement, ideally based on multidisciplinary evaluation.

Using anti-malondialdehyde-modified peptide adduct autoantibodies in serum of taiwanese women to diagnose primary Sjogren's syndrome

BACKGROUND

Sjogren's syndrome (SS) is a systemic autoimmune disease featured with a dry mouth and dry eyes. Several autoantibodies, including anti-SSA, anti-SSB, antinuclear antibodies can be detected in patients with SS. Oxidation-specific epitopes (OSEs) can be formed from malondialdehyde (MDA)-modified protein adducts and trigger chronic inflammation. In this study, our purposes were used serum levels of anti-MDA-modified peptide adducts autoantibodies to evaluate predictive performance by machine learning algorithms in primary Sjögren's syndrome (pSS) and assess the association between pSS and healthy controls.

METHODS

Three novel MDA-modified peptide adducts, including immunoglobulin (Ig) gamma heavy chain 1 (IGHG1)^102-131, complement factor H (CFAH)^1045-1062_, and Ig heavy constant alpha 1 (IGHA1)^307-327 were identified and validated. Serum levels of protein, MDA-modified protein adducts, MDA, and autoantibodies recognizing unmodified peptides and MDA-modified peptide adducts were measured. Statistically significance in correlations and odds ratios (ORs) were estimated.

RESULTS

The random forest classifier utilized autoantibodies combination composed of IgM anti-IGHG1^102-131, IgM anti-IGHG1^102-131 MDA and IgM anti-IGHA1^307-327 achieved predictive performance as an accuracy of 88.0%, a sensitivity of 93.7%, and a specificity of 84.4% which may be as potential diagnostic biomarkers to differentiate patients with pSS from rheumatoid arthritis (RA), and secondary SS in RA and HCs.

CONCLUSIONS

Our findings imply that low levels of IgA anti-IGHG1^102-131 MDA (OR = 2.646), IgA anti-IGHG1^102-131 (OR = 2.408), IgA anti-CFAH^1045-1062 (OR = 2.571), and IgA anti-IGHA1^307-327 (OR = 2.905) may denote developing risks of pSS, respectively.

Decreased BAFF Receptor Expression and Unaltered B Cell Receptor Signaling in Circulating B Cells from Primary Sjögren's Syndrome Patients at Diagnosis

Animal models of autoimmunity and human genetic association studies indicate that the dysregulation of B-cell receptor (BCR) signaling is an important driver of autoimmunity. We previously showed that in circulating B cells from primary Sjögren’s syndrome (pSS) patients with high systemic disease activity, protein expression of the BCR signaling molecule Bruton’s tyrosine kinase (BTK) was increased and correlated with T-cell infiltration in the target organ. We hypothesized that these alterations could be driven by increased B-cell activating factor (BAFF) levels in pSS. Here, we investigated whether altered BCR signaling was already present at diagnosis and distinguished pSS from non-SS sicca patients. Using (phospho-)flow cytometry, we quantified the phosphorylation of BCR signaling molecules, and investigated BTK and BAFF receptor (BAFFR) expression in circulating B cell subsets in an inception cohort of non-SS sicca and pSS patients, as well as healthy controls (HCs). We found that both BTK protein levels and BCR signaling activity were comparable among groups. Interestingly, BAFFR expression was significantly downregulated in pSS, but not in non-SS sicca patients, compared with HCs, and correlated with pSS-associated alterations in B cell subsets. These data indicate reduced BAFFR expression as a possible sign of early B cell involvement and a diagnostic marker for pSS.

Approaches for the detection and analysis of anti-drug antibodies to biopharmaceuticals: A review

Antibody-based therapeutic agents and other biopharmaceuticals are now used in the treatment of many diseases. However, when these biopharmaceuticals are administrated to patients, an immune reaction may occur that can reduce the drug's efficacy and lead to adverse side effects. The immunogenicity of biopharmaceuticals can be evaluated by detecting and measuring antibodies that have been produced against these drugs, or anti-drug antibodies (ADAs). Methods for ADA detection and analysis can be important during the selection of a therapeutic approach based on such drugs and is crucial when developing and testing new biopharmaceuticals. This review examines approaches that have been used for ADA detection, measurement, and characterization. Many of these approaches are based on immunoassays and antigen binding tests, including homogeneous mobility shift assays. Other techniques that have been used for the analysis of ADAs are capillary electrophoresis, reporter gene assays, surface plasmon resonance spectroscopy, and liquid chromatography-mass spectrometry. The general principles of each approach will be discussed, along with their recent applications with regards to ADA analysis. This article is protected by copyright. All rights reserved.

Autoantibodies in Sjögren's syndrome and its classification criteria

Sjögren's syndrome (SS) is a systemic autoimmune disease characterized by immune-mediated injury of exocrine glands. Extensive lymphocytic infiltrates may contribute to the destruction and loss of secretory function of glands. B-cell hyperactivity is a key feature of the disease resulting in the production of a diverse array of autoantibodies in these patients. Although not specific for SS, anti-Ro/SSA and anti-La/SSB antibodies have been useful biomarkers for disease classification and diagnosis. During recent years, novel autoantibodies have been discovered in SS. In this review, we summarize the historical role and clinical relevance that autoantibodies have played in the classification criteria of Sjögren's syndrome, discuss laboratory aspects in antibody detection and review the role of novel autoantibodies in predicting particular stages of the disease, clinical phenotypes and long-term complications.

Current state of technologies and recognition of anti-SSA/Ro antibodies in China: A multi-center study

Background

Previous studies have demonstrated that Ro60 and Ro52 have different clinical implications, and anti‐Ro52 antibodies are an independent serum marker of systemic autoimmune diseases, including Sjögren's syndrome. Many different assays have been adopted to detect anti‐Sjögren's syndrome antigen A (SSA)/Ro antibodies, while to date no specific approach has been recommended as optimal for anti‐SSA/Ro antibody testing. Herein, we performed a multi‐center study to explore the current clinical utility of different strategies for anti‐SSA/Ro antibody testing in China.

Methods

Twenty‐one tertiary care centers were included in this questionnaire‐based study. The self‐administered questionnaire mainly includes testing methods for anti‐SSA/Ro antibodies, reporting system of results, and interpretation of results by clinicians.

Results

Six different methods were applied to detect anti‐SSA/Ro antibodies in the 21 centers. Line immunoassay (eight different commercial kits) was the most frequently adopted method (21/21, 100%), with different cutoff values and strategies for intensity stratification. There were two reporting systems: One was reported as “anti‐SSA antibodies” and “anti‐Ro52 antibodies” (12/21, 57%), while the other was “anti‐SSA/Ro60 antibodies” and “anti‐SSA/Ro52 antibodies” (9/21, 43%). Notably, six centers (29%) considered either positive anti‐Ro60 or anti‐Ro52 antibodies as positive anti‐SSA antibodies, all of which adopted the latter reporting system.

Conclusion

Significant variabilities existed among anti‐SSA/Ro assays. Nearly 30% of centers misinterpreted the definition of positive anti‐SSA antibodies, which may be attributed to the confusing reporting systems of line immunoassay. Therefore, we advocate standardization of the nomenclature of anti‐SSA/Ro antibodies, changing the “anti‐SSA/Ro52” label in favor of the “anti‐Ro52” antibodies for a clear designation.

Immunological characteristics and effect of cyclosporin in patients with immune thrombocytopenia

Objective

Immune thrombocytopenia (ITP) is well‐known as an antibody‐mediated autoimmune disease, and it is easy to get response but often turns to relapse or refractory. Cyclosporin is a traditional immunosuppressant and had a good effect on ITP patients. In this paper, we retrospectively analyze the immunological characteristics and therapeutic effect of cyclosporin in 220 patients with ITP.

Methods

All newly diagnosed ITP patients in the Department of Hematology, Tianjin Medical University General Hospital from June 2018 to December 2020 were enrolled and divided into four groups according to the expression of autoantibodies and the occurrence of prodromal infection. The basic data and immune indexes of ITP patients in each group were collected. The clinical immunological characteristics of patients in each group and the therapeutic effect of cyclosporin in each group were analyzed.

Results

Multi‐autoantibody ITP patients were more likely to have low serum albumin and high gamma globulin, and the ratio of albumin to globulin decreased. In addition, the level of IgA and IgG increased and the level of complement C3 and C4 decreased more frequently than those in other groups. The number of CD3+T lymphocytes, especially CD3+CD4+T lymphocytes, decreased in ANA+ITP patients. The number of CD16+CD56+NK cells, pDC/DC ratio, and pDC/mDC ratio were higher than those in other groups. The expression of IL‐6 and the proportion of CD19+B lymphocytes increased in two groups of ITP patients with abnormal autoantibodies. The patients of pro‐infected group were more likely to suffer from coagulation disorder. After treatment with cyclosporin, the response rate increased and the 3‐month relapse rate decreased in all ITP patients, and the therapeutic effect of patients with high megakaryocyte number was significantly higher than that of patients with low megakaryocyte number. The impact factors that influence the effect of glucocorticoid and(or) IVIG were the number of CD3+CD8+T lymphocytes, CD4/CD8 cell ratio, and the number of CD19+B lymphocytes. The independent impact factor of cyclosporin therapeutic response rate was the number of CD3+T lymphocytes.

Conclusions

ITP is a heterogeneous disease, recurrence may occur during or rapidly after treatment. Cyclosporine included treatment can improve the effective rate of ITP and reduce the relapse rate within 3 months. The number of CD3+T lymphocytes was the only impact factor that influence the therapeutic effect of cyclosporin in ITP patients.

Complement Activation in Patients With Probable Systemic Lupus Erythematosus and Ability to Predict Progression to American College of Rheumatology-Classified Systemic Lupus Erythematosus

Objective

To evaluate the frequency of cell‐bound complement activation products (CB‐CAPs) as a marker of complement activation in patients with suspected systemic lupus erythematosus (SLE) and the usefulness of this biomarker as a predictor of the evolution of probable SLE into SLE as classified by the American College of Rheumatology (ACR) criteria.

Methods

Patients in whom SLE was suspected by lupus experts and who fulfilled 3 ACR classification criteria for SLE (probable SLE) were enrolled, along with patients with established SLE as classified by both the ACR and the Systemic Lupus International Collaborating Clinics (SLICC) criteria, patients with primary Sjögren's syndrome (SS), and patients with other rheumatic diseases. Individual CB‐CAPs were measured by flow cytometry, and positivity rates were compared to those of commonly assessed biomarkers, including serum complement proteins (C3 and C4) and autoantibodies. The frequency of a positive multianalyte assay panel (MAP), which includes CB‐CAPs, was also evaluated. Probable SLE cases were followed up prospectively.

Results

The 92 patients with probable SLE were diagnosed more recently than the 53 patients with established SLE, and their use of antirheumatic medications was lower. At the enrollment visit, more patients with probable SLE were positive for CB‐CAPs (28%) or MAP (40%) than had low complement levels (9%) (P = 0.0001 for each). In probable SLE, MAP scores of >0.8 at enrollment predicted fulfillment of a fourth ACR criterion within 18 months (hazard ratio 3.11, P < 0.01).

Conclusion

Complement activation occurs in some patients with probable SLE and can be detected with higher frequency by evaluating CB‐CAPs and MAP than by assessing traditional serum complement protein levels. A MAP score above 0.8 predicts transition to classifiable SLE according to ACR criteria.

Reducing the risk of misdiagnosis of indirect ELISA by normalizing serum-specific background noise: The example of detecting anti-FGFR3 autoantibodies

Indirect enzyme-linked immunosorbent assay (ELISA) is an important diagnostic method as it enables the quantification of the presence of autoantibodies in human blood sera. However, unspecific binding of antibodies to the solid phase causes considerable serum-specific background noise (SSBN), involving the risk of false positive diagnosis. Therefore, we present a simple and concise, yet obvious proof-of-principle of a recently suggested normalization method. The method is based on subtracting SSBN by using non-coated ELISA wells as a control for each serum-of-interest. We performed ELISA to quantify anti-fibroblast growth factor receptor 3 (FGFR3) antibody levels in three positive controls (two anti-FGFR3-positive patients and a rabbit antiserum against FGFR3) and 58 negative controls (healthy blood donors). In all subjects, we found considerable unspecific reactivity which strongly varied among subjects. The conventional normalization method was not able to balance this strong SSBN, as demonstrated by 2/58 false positive healthy controls and one FGFR3-positive patient that was hidden in the noise (false negative). SSBN normalization reduced the frequency of false-positives to 0/58. Further, all three anti-FGFR3-positive sera were successfully detected and even doubled their z-score used to determine positivity. Albeit occupying more space on the ELISA plate, we strongly recommend considering this normalization method when working with blood sera. To better put the idea across to the community, we depict the SSBN issue and its solution in a graphic scheme. We conclude that SSBN normalization increases the sensitivity and specificity of indirect ELISA and thereby reduces the risk of false positive and false negative diagnosis. © 2019. Licensed under the Creative Commons [CC BY-NC 4.0 licence, https://doi.org/10.1016/j.jim.2019.01.004].

Detection of SSA and SSB Antibodies Associated with Primary Sjögren's Syndrome Using Enzyme-Linked Immunosorbent Assay

Antibodies to Ro52/Ro60 (SSA) and La (SSB) are strongly associated to the autoimmune disease primary Sjögren's syndrome and are important in the serologic diagnosis of the disease. Several methods for detection of these antibodies exist such as indirect immunofluorescence, commercial western blot kits, in-house assays, and numerous commercial enzyme-linked immunosorbent assays (ELISAs). Dependent on the type of assay, sensitivity and specificity may vary notably. Especially ELISAs, where the antibody reactivity to synthetic peptides, recombinant or native proteins are determined, are often applied. This chapter describes detection of SSA and SSB antibodies by ELISA.

Association between memory B-cells and clinical and immunological features of primary Sjögren's syndrome and Sicca patients

B-cells play a pivotal role in primary Sjögren's syndrome (pSS) pathogenesis. We aim to (1) evaluate the distribution of B-lymphocyte subpopulations in pSS and Sicca patients, (2) establish cut-off points that discriminate pSS from controls, (3) evaluate the association between memory B-cells and phenotypic features in pSS. We included 57 pSS patients, 68 Sicca and 24 healthy controls. Circulating B-cells were characterized by flow cytometry as naïve and memory subsets and classified from Bm1 to Bm5. Compared to controls, pSS patients had lower percentages (29.5 vs 44.4%) and absolute numbers (47 vs 106 cells/µl) of memory B-cells. Through ROC curves, a cut-off of ≤ 58 total memory B-cells/µl yielded a specificity of 0.88 and a sensitivity of 0.60 for pSS, and was met by 59.6% of pSS patients, 38.8% of Sicca and 12.5% of controls. A cut-off of < 23.5 Switched-memory B-cells/µl yielded a specificity of 0.88 and a sensitivity of 0.54 and was met by 54.4% of pSS patients, 37.3% of Sicca and 12.5% of controls. In pSS, lower total memory B-cells count was associated with longer disease duration (14.3 vs 8.1 years, p = 0.006) and more active disease profile, as evaluated by the European League Against Rheumatism (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI) (3.1 vs 1.4, p = 0.043). Decreased numbers of memory B-cells clearly discriminated pSS from controls and can also have prognostic value. It remains to be clarified whether Sicca patients with decreased memory B-cells represent pSS and if B-cell profiling could help in the diagnosis of pSS.

Low titer, isolated anti Ro/SSA 60 kd antibodies is correlated with positive pregnancy outcomes in women at risk of congenital heart block

Congenital heart block (CHB) is an autoantibody mediated disorder presumably caused by placental transmission of maternal autoantibodies to Ro/SSA 52 kd, p200, Ro/SSA 60 kd, La/SSB ribonucleoproteins. This study investigated the clinical significance of isolated anti-Ro/SSA 52 kd, anti-p200, anti-Ro/SSA 60 kd, and anti-La/SSB antibodies in positive pregnant patients. One hundred sixty-three pregnant women positive to anti-Ro/SSA 52 kd and/or anti-Ro/SSA 60 kd and/or anti-La/SSB antibodies were prospectively enrolled in the study. Anti-Ro52, anti-Ro60, anti-p200, and anti-La antibodies were assayed using home-made ELISA assays. Isolated antibody positivity was found in 25 women (15.3%), while multiple antibody positivity in 138 (84.7%). Twenty-four developed CHB, and the 139 had a favorable pregnancy outcome. The prevalence of isolated anti-Ro/SSA 60 kd antibodies was significantly higher (p < 0.046) as the prevalence of lower mean antibody titers (p < 0.0001) in the later group. Confirmation of these results by large-scale studies could lead clinicians to recommend less stringent fetal echocardiography monitoring in women with isolated anti-Ro/SSA 60 kd antibodies.