Prevalence, persistence and clinical correlations of classic and novel antiphospholipid antibodies in systemic lupus erythematosus

Impact of antiphospholipid antibodies on cardiac valve lesions in systemic lupus erythematosus: a systematic review and meta-analysis

This meta-analysis assesses antiphospholipid antibodies' (aPLs) impact on heart valve disease in Systemic Lupus Erythematosus (SLE) patients. We searched PubMed, Embase, Cochrane, and Web of Science up to January 2024 for comparative studies of heart valve disease in aPL-positive versus aPL-negative SLE patients. Fixed-effect or random-effect models were used to synthesize data, with I2 and sensitivity analyses for heterogeneity and the trim-and-fill method for publication bias. Including 25 studies with 8089 patients, of which 919 had valvular changes, aPLs significantly increased the risk of heart valve disease (OR = 2.24, 95% CI: 1.58-3.18, p < 0.001). Lupus anticoagulant (LA) indicated the highest risk (OR = 4.90, 95% CI: 2.26-10.60, p < 0.001), anticardiolipin antibodies (aCL) doubled the risk (OR = 2.69, 95% CI: 1.47-4.93, p = 0.001), and anti-β2 glycoprotein I (aβ2GPI) showed a 70% increase (OR = 1.70, 95% CI: 1.17-2.45, p = 0.005). Valve-specific analysis indicated the mitral valve was most commonly involved (26.89%), with higher occurrences in aPL-positive patients (33.34% vs. 15.92%, p = 0.053). Aortic and tricuspid valve involvements were 13.11% vs. 5.42% (p = 0.147) and 12.03% vs. 8.52% (p = 0.039), respectively. Pulmonary valve disease was rare and similar across groups (1.01% in aPL-positive vs. 1.52% in aPL-negative). Significantly, only tricuspid valve disease showed increased risk in aPL-positive patients (OR = 2.66, 95% CI: 1.05-6.75, p = 0.039). APLs notably increase the risk of heart valve disease in SLE patients, with a pronounced effect on tricuspid valve involvement. Regular cardiac assessments for aPL-positive SLE patients are crucial for timely intervention and improved prognosis.

Antiphospholipid antibodies and the risk of adverse pregnancy outcomes in patients with systemic lupus erythematosus: a systematic review and meta-analysis

OBJECTIVE

This article aims to evaluate the magnitude of adverse pregnancy outcomes (APOs) risks associated with different antiphospholipid antibody (aPL) profiles in women with systemic lupus erythematosus (SLE).

METHODS

Multiple databases were investigated to identify articles that explored the relationship between aPLs and APOs in SLE patients. A random effects model was used for calculating pooled odds ratios (OR). Stata version 15.0 was utilized to conduct the meta-analysis.

RESULTS

There were 5234 patients involved in 30 studies. Overall aPL was linked to an increased incidence of any kind of APOs, fetal loss, and preterm birth. Any kind of APOs and preterm delivery were more common in patients with lupus anticoagulant (LA) positive. Anticardiolipin antibody (aCL) was associated with an increased risk of any kind of APOs and fetal loss. The association between aCL-IgM and fetal loss was also significant. Patients with anti-beta2-glycoprotein1 antibody (antiβ2GP1) positivity had an increased risk of fetal loss.

CONCLUSIONS

Both LA and aCL were risk factors of APOs in patients with SLE. Not only ACL, particularly aCL-IgM, but antiβ2GP1 were associated with an increased risk of fetal loss, while LA appeared to indicate the risk of preterm birth.PROSPERO (CRD42023388122).

Unveiling the Link Between Antiphospholipid Antibodies and Cognitive Dysfunction in the Almenara Lupus Cohort

OBJECTIVE

Cognitive dysfunction is a prevalent manifestation of systemic lupus erythematosus (SLE). There is evidence for the role of antiphospholipid (aPL) antibodies on its etiopathogenesis. Our objective was to identify the association between aPL antibodies and cognitive dysfunction in SLE patients.

METHODS

This cross-sectional study included 135 patients evaluated from March 2015 to October 2017 at one center. Cognitive deficit was measured using the NEUROPSI test. Disease activity and damage were ascertained using the SLEDAI-2K (SLE Disease Activity Index 2000) and the SDI (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index), respectively; aPL antibodies were measured by enzyme-linked immunosorbent assay. The association between cognitive dysfunction and aPL antibodies was evaluated using univariable and multivariable linear regression models adjusted for age, sex, education, socioeconomic status, disease duration, SLEDAI-2K, SDI, mean current dose of prednisone, time of exposure to glucocorticoids, and drug use (immunosuppressants, hydroxychloroquine, aspirin, and warfarin).

RESULTS

One hundred thirty-one patients (97.1%) were women; their mean (SD) age was 46.6 (12.5) years; 59 patients (43.7%) had positivity for at least 1 aPL antibody. IgM anticardiolipin (aCL) was positive in 24.5%, IgG in 13.5%, IgM aβ2GP1 in 16.8%, IgG anti-β2 glycoprotein in 24.6%, and the lupus anticoagulant in 5.3%. Ninety patients (66.7%) had some cognitive dysfunction. In the univariable analysis, a significant correlation between the NEUROPSI score and IgM aCL antibodies was found (B = -20.87 [SE, 3.2]; p < 0.001), which remained significant in the multivariable model (B = -13.89 [SE, 3.14]; p < 0.001).

CONCLUSIONS

IgM aCL antibodies are associated with cognitive dysfunction in patients with SLE. Larger and longitudinal studies are needed to assess the impact of these findings.

The impact of antiphospholipid antibodies/antiphospholipid syndrome on systemic lupus erythematosus

aPLs are a major determinant of the increased cardiovascular risk in patients with SLE. They adversely affect clinical manifestations, damage accrual and prognosis. Apart from the antibodies included in the 2006 revised classification criteria for APS, other non-classical aPLs might help in identifying SLE patients at increased risk of thrombotic events. The best studied are IgA anti-β2-glycoprotein I, anti-domain I β2-glycoprotein I and aPS-PT. Major organ involvement includes kidney and neuropsychiatric systems. aPL/APS severely impacts pregnancy outcomes. Due to increased thrombotic risk, these patients require aggressive cardiovascular risk factor control. Primary prophylaxis is based on low-dose aspirin in high-risk patients. Warfarin is the gold-standard drug for secondary prophylaxis.

Machine learning identifies clusters of longitudinal autoantibody profiles predictive of systemic lupus erythematosus disease outcomes

OBJECTIVES

A novel longitudinal clustering technique was applied to comprehensive autoantibody data from a large, well-characterised, multinational inception systemic lupus erythematosus (SLE) cohort to determine profiles predictive of clinical outcomes.

METHODS

Demographic, clinical and serological data from 805 patients with SLE obtained within 15 months of diagnosis and at 3-year and 5-year follow-up were included. For each visit, sera were assessed for 29 antinuclear antibodies (ANA) immunofluorescence patterns and 20 autoantibodies. K-means clustering on principal component analysis-transformed longitudinal autoantibody profiles identified discrete phenotypic clusters. One-way analysis of variance compared cluster enrolment demographics and clinical outcomes at 10-year follow-up. Cox proportional hazards model estimated the HR for survival adjusting for age of disease onset.

RESULTS

Cluster 1 (n=137, high frequency of anti-Smith, anti-U1RNP, AC-5 (large nuclear speckled pattern) and high ANA titres) had the highest cumulative disease activity and immunosuppressants/biologics use at year 10. Cluster 2 (n=376, low anti-double stranded DNA (dsDNA) and ANA titres) had the lowest disease activity, frequency of lupus nephritis and immunosuppressants/biologics use. Cluster 3 (n=80, highest frequency of all five antiphospholipid antibodies) had the highest frequency of seizures and hypocomplementaemia. Cluster 4 (n=212) also had high disease activity and was characterised by multiple autoantibody reactivity including to antihistone, anti-dsDNA, antiribosomal P, anti-Sjögren syndrome antigen A or Ro60, anti-Sjögren syndrome antigen B or La, anti-Ro52/Tripartite Motif Protein 21, antiproliferating cell nuclear antigen and anticentromere B). Clusters 1 (adjusted HR 2.60 (95% CI 1.12 to 6.05), p=0.03) and 3 (adjusted HR 2.87 (95% CI 1.22 to 6.74), p=0.02) had lower survival compared with cluster 2.

CONCLUSION

Four discrete SLE patient longitudinal autoantibody clusters were predictive of long-term disease activity, organ involvement, treatment requirements and mortality risk.

Antiphospholipid antibodies are persistently positive at high titers. Additive value of platelet-bound C4d

Background

Classification criteria for antiphospholipid syndrome (APS) require that antiphospholipid antibody (aPL) positivity is confirmed after at least 12 weeks. We tested the hypothesis that aPL at high titers remain positive while low titers fluctuate over time. As both platelet-bound C4d (PC4d) and aPL are associated with thrombosis in systemic lupus erythematosus (SLE), we also evaluated whether PC4d can aid in APS diagnosis.

Methods

Data from serum or plasma sent to Exagen’s laboratory for routine aPL testing were analyzed. Anti-cardiolipin (aCL) and anti-beta2 glycoprotein-1 antibodies (aB2GP1) were measured by chemiluminescence or ELiA fluorescence enzyme immunoassay; anti-phosphatidylserine/prothrombin complex antibodies (aPS/PT) by ELISA; PC4d by flow cytometry. Statistical analysis included descriptive statistics, logistic regression, and Pearson correlation.

Results

More than 80% of positive samples with aCL and aB2GP1 at high titers - but not low titers - were positive at a retest. Non-criteria aPL (aPS/PT) followed a similar trend. aCL and aB2GP1 measured with two different technologies were highly correlated. PC4d and IgG of the three aPL were at best moderately correlated even when only positive aPL samples were analyzed (coefficient: 0.1917 to 0.2649).

Conclusions

High titers aPL are often persistently positive, allowing an earlier diagnosis and risk assessment at the time of the initial screening. Conversely, a retest may be necessary for low titers. The high correlation between two methodologies suggests that these findings are independent of assay platform. The low to moderate correlation between PC4d and aPL might suggest a possible additive value to evaluate association with thrombosis in autoimmune diseases.

Anti-Nuclear Antibodies Patterns in Patients With Systemic Lupus Erythematosus and Their Correlation With Other Diagnostic Immunological Parameters

Background

Antinuclear antibodies (ANA) are major immunodiagnostic tools in systemic lupus erythematosus (SLE); however, their clinical and pathogenic roles are not yet elucidated and are a subject of controversy.

Objectives

The aim of the study is to explore the pathogenic significance of ANA patterns among SLE patients, by analyzing their association with ANA titers, complement levels and other pathogenic immune markers, namely, anti-double-stranded DNA (anti-dsDNA), complements C3 and C4, rheumatoid factor (RF), anticardiolipin antibodies IgG (ACL IgG) and IgM (ACL IgM), Beta-2 Glycoprotein 1 Antibodies (β2-GP) IgG (β2-IgM) and IgM (β2-IgM), and lupus anticoagulant (LA).

Method

A comparative cross-sectional study was conducted among 495 SLE patients, who were diagnosed and classified by consultant rheumatologists according to the new European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) 2019 criteria. SLE immunodiagnostic profiles were analyzed including the following parameters: ANA antibody titers and staining patterns, anti-dsDNA, C3 and C4 levels, aCL, and anti-β2-GP and LA.

Result

The most frequently observed ANA patterns were the speckled (52.1%) and homogeneous (35.2%) patterns, while other patterns were rare representing less than 7% of the patients each. ANA titers were highest in patients with mixed pattern followed by the speckled pattern. Of all the investigated patterns, the peripheral pattern showed the most pathogenic immune profile, namely, highest levels of anti-dsDNA, lowest levels of C4, and highest levels of aCL and β2-GP IgG and IgM.

Conclusion

This retrospective study showed that speckled followed by homogeneous ANA patterns were predominant accounting for 52.1 and 35.2% of the patients. The ANA pattern showed several associations with other immune markers that are documented to have significant clinical implications in SLE. Peripheral, mixed, and speckled patterns were associated with higher profiles of immune markers indicative of a potential prognostic value of these patterns in SLE.

Case Report: A case of recurrent thrombosis in pediatric antiphospholipid syndrome associated with pediatric onset systemic lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease with multi-system involvement as the main manifestation, and has complex and diverse clinical features. Studies on large samples have revealed that SLE patients have a significantly increased risk of thrombotic events, which are also one of the important causes of morbidity and mortality in SLE patients. Antiphospholipid syndrome (APS) is a rare autoimmune disorder characterized by recurrent arterial and venous thrombosis, pregnancy-related complications, and the persistence of antiphospholipid antibodies at a 12-week interval. There are few reports about SLE coexisting with APS in children. This paper reported a school-age patient who started the disease with gross hematuria after bumping into the waist. The initial diagnosis of renal contusion was then confirmed by color Doppler ultrasound as renal vein and inferior vena cava embolism. She suddenly developed severe chest pain and dyspnea 3 days after hospitalization. And imaging supported pulmonary embolism with massive proteinuria, hypoalbuminemia, and hypercholesterolemia. The initial diagnosis was nephrotic syndrome (NS) with arteriovenous embolization, and popliteal vein embolism occurred again 5 years later, and she was thus diagnosed with SLE coexisting with APS. Afterwards, we discussed the possible mechanism and therapeutic strategies of SLE&APS that started with nephrotic syndrome, in order to achieve early identification and treatment of the disease and improve the prognosis of children.

Thrombotic risk assessment in patients with systemic lupus erythematosus: Validation of the adjusted-Global Antiphospholipid Syndrome Score (aGAPSS) in Thai patients

BACKGROUND

The adjusted-Global Antiphospholipid Syndrome Score (aGAPSS) has been validated and used to predict antiphospholipid antibodies (aPL) related to vascular thrombosis (VT).

OBJECTIVE

To validate aGAPSS for predicted aPL-related VT and pregnancy complications (PC) in Thai systemic lupus erythematosus (SLE) patients.

METHODS

A cross-sectional study was performed among Thai SLE patients with clinical manifestations; history of VT and PC, cardiovascular risk factors, and aPL profiles were collected. The aGAPSS was calculated from the sum of the risk factors (hyperlipidemia = 3.0, arterial hypertension = 1.0, anti-cardiolipin antibody = 5.0, anti-b2 glycoprotein I antibody = 4.0, and lupus anticoagulant = 4.0).

RESULTS

Of 132 SLE patients, 12 (9.1%) had VT and 5 (4.1%) had PC. When comparing the aGAPSS (median; interquartile range [IQR]) of patients with events (VT and/or PC) (6.5; IQR 3.3-9.0), VT (8.0; IQR 4.0-9.0), arterial thrombosis (3.5; IQR 1.0-5.8), and PC (9.0; IQR 8.0-11.5), and the aGAPSS of patients without an event (3.0; IQR 0-4.0), aGAPSS of patients with events was significantly higher, except in patients with arterial thrombosis. An aGAPSS of 4.5 or more was associated with risk of aPL-related VT (sensitivity 71.4%, specificity 76.7%), and an aGAPSS of 6.0 or more was associated with risk of aPL-PC (sensitivity 100%, specificity 84.0%).

CONCLUSION

The aGAPSS could predict the risk of aPL-PC and aPL-related VT in Thai SLE patients.

Longitudinal Analysis of Anti-cardiolipin and Anti-β2-glycoprotein-I Antibodies in Recent-Onset Systemic Lupus Erythematosus: A Prospective Study in Swedish Patients

Background: Anti-phospholipid syndrome (APS) and systemic lupus erythematous (SLE) are autoimmune disorders that often co-occur. Anti-phospholipid antibodies (aPL) are typical of both conditions and may be associated with vascular events and pregnancy-related morbidities. Whereas, aPL-screening is mandatory for individuals with suspected SLE, the clinical value of longitudinal aPL analyses in established SLE is unclear.

Methods: We investigated the occurrence and variation of IgG/IgA/IgM anti-cardiolipin (aCL) and anti-β2-glycoprotein-I (anti-β2GPI) antibodies, using both the manufacturer's cut-off and a cut-off based on the 99th percentile of 400 apparently healthy donors, in recent-onset SLE. Furthermore, we evaluated the relationships between aPL levels and SLE/APS manifestations, as well as the pharmacotherapy. Patients with SLE who met validated classification criteria were included in this prospective study (N = 54). Samples were obtained at 0, 6, 12, 24, 36, 48, 60, 72, 84, and 96 months after SLE diagnosis.

Results: Depending on the cut-off applied, 61.1 or 44.4% showed a positive result for at least one aPL isotype or the lupus anticoagulant test over time. Median values for all six aPL isotypes numerically decreased from inclusion to last follow-up, but none of the isotypes met statistical significance. Seroconversion (from positive to negative, or the opposite direction) was occasionally seen for both aCL and anti-β2GPI. IgA and IgM anti-β2GPI were the most common isotypes, followed by IgM aCL. Presence of IgG aCL associated significantly with myocardial infarction and miscarriage, and IgG/IgA anti-β2GPI with miscarriage.

Conclusion: aPL were common during the first years of SLE. Even though the levels fluctuated over time, the patients tended to remain aPL positive or negative. Repeated aPL testing in the absence of new symptoms seems to be of uncertain value in patients with recent-onset SLE.

[Differential Diagnosis of Pulmonary Hypertension Using the Example of Collagenosis-associated PAH in the Context of Chronic Lung and Left Heart Disease]

Pulmonary hypertension (PH) can be diagnosed in the context of connective tissue diseases (CTD) as well as in elderly patients with multiple comorbidities. A correct clinical differential diagnosis and classification is essential before adequate therapeutic decisions can be made. Differential diagnosis of PH in CTD comprises associated pulmonary arterial hypertension (APAH), group 2 or 3 PH (PH arising from left heart or chronic lung disease), chronic thromboembolic PH (PH) and group 5 (e. g. in the context of terminal renal insufficiency). This is also true of elderly patients in whom the decision has to be made if the increasing number of coincident diseases lead to PH or have to be interpreted as comorbidities. In this manuscript, the differential diagnosis of PH is elucidated, focusing on CTD, in the context of left heart disease and chronic lung disease. Furthermore, criteria are presented facilitating an objective approach in this context.

Prevalence of autoantibodies directed against prothrombin in unprovoked venous thromboembolism

The anti-phospholipid syndrome (APS) is defined by the laboratory detection of at least one of three anti-phospholipid autoantibodies (lupus anticoagulant, or anti-cardiolipin or anti-β₂-glycoprotein I antibodies) in the clinical setting of thrombosis or pregnancy morbidity in a patient. Recognising APS and administering appropriate secondary thromboprophylaxis is important to reduce risk of recurrent thrombosis and/or pregnancy morbidity. In some instances, patients having clinical manifestations highly suggestive of APS are persistently negative for these antibodies but instead have other autoantibodies. Autoantibodies directed against prothrombin (PT) have been associated with increased thrombotic risk and comprise anti-prothrombin (aPT) and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies. Detection of aPT and aPS/PT may help stratify patients for more effective treatment, however, their prevalence among patients with unprovoked venous thromboembolism (VTE) is unknown and determination of their frequencies is the objective of this study. Sera from 148 patients with unprovoked VTE were analysed. Autoantibodies directed against PT collectively, aPT and aPS/PT were present in 24.3%, 14.9% and 13.5%, respectively. Prevalence of these autoantibodies in unprovoked VTE is much lower compared to cohorts comprising mainly patients with systemic autoimmune disorders. Detection of these autoantibodies in unprovoked VTE has potential therapeutic implications for patients including the duration of anticoagulation and administration, or otherwise, of direct oral anticoagulants. Data from this study will assist in the design of future clinical studies to estimate risk of recurrent VTE and to determine optimal management.

16th International Congress on Antiphospholipid Antibodies Task Force Report on Obstetric Antiphospholipid Syndrome

Obstetric antiphospholipid syndrome (APS) remains a clinical challenge for practitioners, with several controversial points that have not been answered so far. This Obstetric APS Task Force met on the 16th International Congress on Antiphospholipid Antibodies in Manchester, England, to discuss about treatment, diagnostic and clinical aspects of the disease. This report will address evidence-based medicine related to obstetric APS, including limitations on our current management, the relationship between antibodies against domain 1 of β2GPI and obstetric morbidity, hydroxychloroquine use in patients with obstetric APS and factors associated with thrombosis after obstetric APS. Finally, future directions for better understanding this complex condition are also reported by the Task Force coordinators.

Anti-apolipoprotein A-1 autoantibodies correlate with disease activity in systemic lupus erythematosus

OBJECTIVES

Apolipoprotein A-1 (ApoA-1) is a protein fraction of the high-density lipoproteins with anti-inflammatory and antioxidant properties that play a major role in reverse cholesterol transport. The presence of anti-ApoA-1 IgG has been reported in SLE to be variably associated with disease activity or cardiovascular events (CVEs). We assessed the clinical performance of anti-ApoA-1 IgG and of antibodies directed against its immunodominant F3L1 peptide (F3L1 IgG) in a well-characterized Swiss SLE cohort study.

METHODS

A total of 354 biological samples and interviews from 176 individuals were studied. SLEDAI, clinical characteristics, anamnestic CVEs and therapy details were recorded. Sera were tested for the presence of anti-ApoA-1 IgG, anti-F3L1 IgG, anti-dsDNA IgG and aPL.

RESULTS

Anti-ApoA-1 and anti-F3L1 IgG positivity was associated with higher SLEDAI, mostly due to concomitant positivity of dsDNA IgG and low complement. Variations in time of anti-ApoA-1 IgG correlated positively with variations of anti-dsDNA IgG and inversely to variations of C3 levels. No cross-reactivity was found between anti-ApoA-1 and anti-dsDNA IgG. Positivity for anti-Apo-A1 IgG was more frequent in individuals receiving 10 mg/day or more of prednisone. We did not find any significant association between anti-ApoA-1 IgG positivity and CVEs.

CONCLUSION

Anti-ApoA-1 and anti-F3L1 IgG in SLE correlate strongly with laboratory markers of activity, particularly with the presence and titre of dsDNA IgG. These results confirm and extend previous findings and support the use of anti-ApoA1 IgG in the clinical setting. Their role in CVEs deserves further investigation.

Drug-Induced Lupus, a One-time Hit or a Harbinger of Future Autoimmunity: A Case Report

INTRODUCTION

Drug-induced lupus (DIL) can comprise up to 10% of new lupus cases annually, and the list of medications associated with DIL is increasing. However, it can be difficult to recognize the connection between symptoms and a medication-induced autoimmune syndrome, which can lead to an invasive, costly workup. Given that the prognosis is usually good if therapy with the offending agent is stopped, it is important to identify this clinical entity promptly.

CASE PRESENTATION

A healthy, 44-year-old man with hypertension was seen initially because of shoulder pain and again after development of fevers and chest pain. He underwent a thorough infectious workup and then oncologic workup, with his clinical course complicated by a Histoplasma infection. After evaluation by subspecialists, the patient was thought to have an autoimmune condition related to DIL. His symptoms improved after he discontinued the offending drug therapy and received a course of corticosteroids.

DISCUSSION

Our case highlights how DIL should be on the differential when seemingly disparate symptoms develop in a patient receiving DIL-associated medications. Lupus is one of the "great imitators," in which symptoms can be ascribed to many different underlying causes. Although this patient's presentation may have been confounded by concomitant histoplasmosis, his improvement with cessation of hydralazine treatment argues in favor of DIL. His continued atypical serologic test results could be residual from his DIL and should normalize with time. However, it raises the question whether this bout of DIL has unmasked a previously quiescent autoimmune condition, requiring continued observation.

Infertility in women with systemic autoimmune diseases

Infertility consists by definition in" failure to achieve a clinical pregnancy after 12 months or more of regular unprotected intercourse" while the term subfertility means a delay to achieve pregnancy. Several factors can contribute to infertility or subfertility in patients with systemic autoimmune diseases. The association of systemic autoimmune conditions with endometriosis, celiac disease and thyroid autoimmunity that are well known causes of infertility and/or subfertility need to be taken in consideration when difficulties in the onset of pregnancy is reported. The majority of the used antirheumatic drugs do not interfere with fertility. However, the use of cyclophosphamide, limited to severe disease, can provoke premature ovarian failure; to preserve fertility a preventive treatment is available. Nonsteroidal anti-inflammatory drugs can cause temporary infertility and corticosteroids are associated to a prolonged time to pregnancy in some rheumatic diseases. Data on the association of antiphospholipid antibodies (aPL) with infertility are still debated but in general an increased rate of aPL is described patients undergoing medically assisted reproductive techniques. In systemic lupus erythematosus aPL and other autoantibodies (i.e. anti-oocytes) can contribute to the infertility of some patients. Subfertility, rather than infertility, is observed in patients with rheumatoid arthritis; the particular physical conditions of these women can also account for this. Physicians should not forget the patients' age, that is mandatory in order to preserve their chance to have children.

Anti-C1q Antibodies as Occurring in Systemic Lupus Erythematosus Could Be Induced by an Epstein-Barr Virus-Derived Antigenic Site

Previous infection with Epstein-Barr virus (EBV) is believed to trigger autoimmunity and to drive autoantibody generation as occurring in patients with systemic lupus erythematosus (SLE). Complement C1q and autoantibodies targeting it (anti-C1q) are also considered to be involved in the pathogenesis of SLE, independently of the impact of environmental insults. Still, the circumstances under which these autoantibodies arise remain elusive. By studying a major antigenic site of C1q targeted by anti-C1q (A08), we aimed to determine environmental factors and possible mechanisms leading to the development of anti-C1q. First, we determined antigenic residues of A08 that were critical for the binding of anti-C1q; importantly, we found the binding to depend on amino-acid-identity. Anti-C1q of SLE patients targeting these critical antigenic residues specifically cross-reacted with the EBV-related EBNA-1 (Epstein-Barr virus nuclear antigen 1)-derived peptide EBNA348. In a cohort of 180 SLE patients we confirmed that patients that were seropositive for EBV and recognized the EBNA348 peptide had increased levels of anti-A08 and anti-C1q, respectively. The correlation of anti-EBNA348 with anti-A08 levels was stronger in SLE patients than in matched healthy controls. Finally, EBNA348 peptide-immunization of C1q^−/− mice induced the generation of cross-reactive antibodies which recognized both the A08 epitope of C1q and intact C1q. These findings suggest that anti-C1q in SLE patients could be induced by an EBV-derived epitope through molecular mimicry, thereby further supporting the pathogenic role of EBV in the development of SLE. Considering the role of C1q and anti-C1q, modifying the anti-EBV response might be a promising strategy to improve the course of the disease.

Methodology of generation and purification of anti-beta 2 glycoprotein I antibodies

In this Method Article we are showing the methodology for generation and purification of Anti-Beta 2 Glycoprotein I (β₂GPI) antibodies. First β₂GPI was purified from human plasma, and recognized by Western Blot and anti-β₂GPI antibodies of serum from patients with antiphospholipid syndrome (APS). The C57BL/6 mice were immunized intraperitonealy with 150 μg of protein in adjuvant (β₂GPI or bovine serum albumin) on days 1, 8 and 14. Then the anti-β₂GPI antibodies were purified by affinity chromatography (Affi-Gel protein A sepharose) and affinity column using human β₂GPI coupled to CNBr-activated Sepharose 4B. Titles of anti-β₂GPI antibodies were determined by ELISA assays.

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We purified β₂GPI with great efficacy and that is recognized antigenically by serum from patients with SAP or an anti-β₂gpi antibody.

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We found that our purified antibody had 13 fold increased activity in ELISA test compared with the control and in Western Blot recognized with β₂GPI (reference and purified).

Prevalence and Significance of Non-conventional Antiphospholipid Antibodies in Patients With Clinical APS Criteria

Background: The biological diagnostics of antiphospholipid syndrome (APS) takes into account the persistent positivity for anticardiolipin and/or anti-β2GP1 antibodies and/or presence of lupus anticoagulant (LA). However, some non-conventional antiphospholipid antibodies have emerged that could help in the diagnosis of APS.

Objectives: To study the potential usefulness of non-conventional antiphospholipid antibodies in clinical practice.

Methods: Eighty-seven patients, aged from 15 to 92 years were included and classified in following groups: 41 patients positive for the conventional antibodies with clinical criterion of APS (31 with primary APS and 10 secondary), 17 seronegative APS (SNAPS) patients (i.e., persistent negativity for the conventional antibodies with a strong clinical suspicion of APS), 11 asymptomatic antiphospholipid antibodies carriers (i.e., persistent positivity for the conventional antibodies without clinical evidence of APS), and 18 patients presenting with a first thrombotic or obstetrical event. IgG and IgM were detected to the following antigens: phosphatidylserine/prothrombin (PS/PT) by ELISA, and phosphatidic acid, phosphatidyl-ethanolamine, phosphatidyl-glycerol, phosphatidyl-inositol, phosphatidylserine, annexin V, prothrombin by immunodot. Anti-β2GP1 IgA, and anti-β2GP1 domain 1 IgG were detected by chemiluminescence.

Results: Positivity for the non-conventional antibodies was correlated with APS severity; patients with catastrophic APS (CAPS) being positive for 10.7 (Median, Range: 5–14) non-conventional antibodies. 9/17 seronegative patients were positive for at least one of non-conventional antibodies. A study of non-supervised hierarchical clustering of all markers revealed that anti-PS/PT antibodies showed high correlation with the presence of LA. All patients with APS triple positivity (highest risk profile) exhibited also persistent positivity for anti-PS/PT antibodies.

Conclusions: Our data obtained from a prospective cohort constituted mainly by patients with primary APS, suggest that non-conventional APS antibodies may be useful for patients classified as SNAPS. They demonstrate the potential value of aPS/PT antibodies as a strong marker of APS. We propose that anti-PS/PT antibodies could be a surrogate APS biological marker of LA to classify in high-risk profile patients treated by direct oral anticoagulants (DOACs), in whom LA detection cannot be achieved.

The clinical value of assays detecting antibodies against domain I of β2-glycoprotein I in the antiphospholipid syndrome

As the clinical symptoms of the antiphospholipid syndrome (APS) frequently occur irrespective of the syndrome, diagnosis predominantly depends on the laboratory assays measuring the level or function of antiphospholipid antibodies (aPLs). β2-glycoprotein I (β2GPI) is increasingly accepted as the most important target of aPLs. Anti-β2GPI antibodies constitute a heterogeneous population, but current in vivo and in vitro evidence show that especially the first domain (DI) of β2GPI contains an important pathogenic epitope. This epitope containing Glycine40-Arginine43 (G40-R43) has proven to be cryptic and only exposed when β2GPI is in its open conformation. A previous study demonstrated a highly variable exposure of the cryptic epitope in commercial anti-β2GPI assays, with implications on correct patient classification. Unexpectedly, recent unpublished data revealed impaired exposure of the pathogenic epitope in the commercially available anti-DI chemiluminescence immunoassay (CIA) assay detecting specific antibodies directed to DI. In this review we summarize the laboratory and clinical performance characteristics of the different anti-DI assays in published data and conclude with inconsistent results for both the correlation of anti-DI antibodies with clinical symptoms and the added value of anti-DI antibodies in the classification criteria of APS. Additionally, we hypothesize on possible explanations for the observed discrepancies. Finally, we highly advise manufacturers to use normal pooled plasma spiked with the monoclonal anti-DI antibodies to verify correct exposure of the cryptic epitope.

Immunoglobulin A anti-phospholipid antibodies in Swedish cases of systemic lupus erythematosus: associations with disease phenotypes, vascular events and damage accrual

Immunoglobulin (Ig) G- and IgM-class anti-cardiolipin antibodies (aCL) and lupus anti-coagulant (LA) are included in the 1997 update of the American College of Rheumatology (ACR-97) systemic lupus erythematosus (SLE) criteria. Despite limited evidence, IgA-aCL and IgA anti-β₂ -glycoprotein-I (anti-β₂ GPI) were included in the 2012 Systemic Lupus International Collaborating Clinics criteria. The present study aimed to evaluate IgG-/IgA-/IgM-aCL and anti-β₂ GPI occurrence in relation to disease phenotype, smoking habits, pharmacotherapy, anti-phospholipid syndrome (APS) and organ damage among 526 Swedish SLE patients meeting ACR-97. Patients with rheumatoid arthritis (n = 100), primary Sjögren's syndrome (n = 50) and blood donors (n = 507) served as controls. Anti-phospholipid antibodies (aPL) were analysed by fluoroenzyme-immunoassays detecting aCL/anti-β₂ GPI. Seventy-six (14%) SLE cases fulfilled the Sydney APS-criteria, and ≥ 1 aCL/anti-β₂ GPI isotype (IgG/IgA/IgM) occurred in 138 SLE patients (26%). Forty-five (9%) of the SLE cases had IgA-aCL, 20 of whom (4%) lacked IgG-/IgM-aCL. Seventy-four (14%) tested positive for IgA anti-β₂ GPI, 34 (6%) being seronegative regarding IgG/IgM anti-β₂ GPI. Six (1%) had APS manifestations but were seropositive regarding IgA-aCL and/or IgA anti-β₂ GPI in the absence of IgG/IgM-aPL and LA. Positive LA and IgG-aPL tests were associated with most APS-related events and organ damage. Exclusive IgA anti-β₂ GPI occurrence associated inversely with Caucasian ethnicity [odds ratio (OR) = 0·21, 95% confidence interval (CI) = 0·06-0·72) and photosensitivity (OR = 0·19, 95% CI = 0·05-0·72). Nephritis, smoking, LA-positivity and statin/corticosteroid-medication associated strongly with organ damage, whereas hydroxychloroquine-medication was protective. In conclusion, IgA-aPL is not rare in SLE (16%) and IgA-aPL analysis may have additional value among SLE cases with suspected APS testing negative for other isotypes of aPL and LA.