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

Antibody profiles in the mosaic of 'seronegative' APS syndrome

Clinical manifestations, as distinct from thrombotic and obstetric morbidity, were recently included in the update of classification criteria of the antiphospholipid syndrome (APS). However, the existence of several patients with clinical manifestations suggestive of APS, but negative for criteria antiphospholipid antibodies (aPLs) [anti-cardiolipin antibodies (aCL), anti-β2-glycoprotein I antibodies (aβ2-GPI), and lupus anticoagulant] may suggest an update of diagnostic criteria. In this study, we analysed the prevalence of six non-criteria aPLs in a large monocentric cohort of patients with seronegative APS (SN-APS), to investigate their possible diagnostic role. aCL IgA, aβ2-GPI IgA, and aβ2-GPI Domain 1 antibodies were detected by chemiluminescence, anti-phosphatidylserine/prothrombin (aPS/PT) IgG, anti-vimentin/cardiolipin (aVim/CL) IgG, and anti-carbamylated-β2-glycoprotein I (aCarb-β2-GPI) IgG by ELISA in sera from 144 SN-APS patients. In SN-APS patients, aCL IgA was detected in 4/144 (2.77%), aβ2-GPI IgA in 2/144 (1.39%), aβ2-GPI-Domain 1 in 1/144 (0.69%), aPS/PT in 16/144 (11.11%), aVim/CL in 37/144 (25.69%), and aCarb-β2-GPI in 43/144 patients (29.86%). Patients negative for all non-criteria aPL assays were 77/144 (53.47%). Notably, the Venn diagram showed that aCarb-β2-GPI together with aVim/CL represented the prevalent combination of positive antibodies. In SN-APS patients, aCL IgA were associated with recurrent thrombosis (OR 11.48; P = 0.03); in obstetric SN-APS patients, aPS/PT were significantly associated with foetal deaths (OR 4.84; P = 0.01), aVim/CL with spontaneous abortions (OR 2.71; P = 0.016). This study indicates that aPS/PT, aVim/CL and aCarb-β2-GPI antibodies may represent useful tools to identify 'seronegative' APS patients, who are negative for criteria aPLs, supporting the need to make testing for non-criteria aPLs more accessible in patients with SN-APS.

Impact of Antiphospholipid Syndrome on Reproductive Outcomes: Current Insights and Management Approaches

Antiphospholipid syndrome (APS) is a disease characterized by the presence of antiphospholipid (aPL) antibodies, thrombosis, and obstetric complications. While patients with APS can have successful pregnancies, many important considerations exist. APS can also cooccur with other systemic autoimmune diseases which can affect pregnancy, particularly systemic lupus erythematosus. This article reviews specific considerations for pregnancy and reproductive health in patients with APS. Similar to other autoimmune diseases, stable or quiescent disease and planning with a rheumatologist and obstetrician prior to conception are vital components of a successful pregnancy. Pregnancy management for patients with aPL antibodies or diagnosis of APS with aspirin and/or anticoagulation depending on disease profile is discussed, as well as the effects of physiologic changes during pregnancy in maternal and fetal outcomes for this population. Given the reproductive span lasts beyond conception through delivery, we include discussions on safe contraception options, the use of assistive reproductive technology, pregnancy termination, menopause, and male fertility. While APS is a relatively rare condition, the effects this disease can have on maternal and fetal outcomes even with available therapies demonstrates the need for more high-quality, evidence-based research.

Thrombosis in Antiphospholipid Syndrome: Current Perspectives and Challenges in Laboratory Testing for Antiphospholipid Antibodies

Antiphospholipid syndrome (APS) diagnosis hinges on identifying antiphospholipid antibodies (aPL). Currently, laboratory testing encompasses lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) IgG or IgM, which are included in the APS classification criteria. All the assays needed to detect aPL antibodies have methodological concerns. LA testing remains challenging due to its complexity and susceptibility to interference from anticoagulant therapy. Solid phase assays for aCL and aβ2GPI exhibit discrepancies between different assays. Antibody profiles aid in identifying the patients at risk for thrombosis through integrated interpretation of all positive aPL tests. Antibodies targeting domain I of β2-glycoprotein and antiphosphatidylserine-prothrombin antibodies have been evaluated for their role in thrombotic APS but are not yet included in the APS criteria. Detecting these antibodies may help patients with incomplete antibody profiles and stratify the risk of APS patients. The added diagnostic value of other methodologies and measurements of other APS-associated antibodies are inconsistent. This manuscript describes laboratory parameters useful in the diagnosis of thrombotic APS and will concentrate on the laboratory aspects, clinical significance of assays, and interpretation of aPL results in the diagnosis of thrombotic APS.

The lupus anticoagulant titer is associated with elevated antiphosphatidylserine/prothrombin immunoglobulin-M isotype antibody levels

BACKGROUND

Clot based assays used for lupus anticoagulant (LAC) detection are typically interpreted in a qualitative fashion and may not reflect LAC potency. In this cross-sectional study, we describe a method for quantifying the LAC titer using serial (dependent) two-fold dilutions in normal pooled plasma.

METHODS

Serial dilutions of 51 residual plasma samples from 50 patients were tested using the Russell's viper venom screening time (DRVVT) and activated partial thromboplastin screening time (APTT) methodologies. The measured clotting times and the corresponding dilution factors were then used to derive a four-parameter logistic model. The LAC titer for each patient was interpolated as the sample dilution that corresponds to the upper reference interval limit of the corresponding assay.

RESULTS

Calculated APTT and DRVVT LAC titers displayed a strong linear correlation (R2 = 0.84) between each other, but not with the degree of prolongation of the APTT/DRVVT screening time in the neat undiluted samples. Using data driven partitioning, patients could be grouped into low (<10) or high (≥10) DRVVT LAC titer. There were no significant differences in anticardiolipin (aCL) or anti-beta 2 glycoprotein 1 (aB2GPI) antibody levels or prevalence of thromboembolic events between low and high LAC titer groups. In contrast, antiphosphatidylserine/prothrombin (aPS/PT) IgM antibody levels, but not IgG, were significantly higher in the high LAC titer group.

CONCLUSIONS

The degree of prolongation of the APTT/DRVVT screening time is not correlated with the LAC titer. Only aPS/PT IgM antibodies levels were strongly correlated with the LAC titers. Additional studies are warranted to determine clinical implications of high LAC titers.

Noncriteria antiphospholipid antibodies in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by thrombotic manifestations and/or obstetric complications in patients with persistently positive antiphospholipid antibodies (aPL). aPL are a heterogeneous group of autoantibodies, but only lupus anticoagulant, anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are included as laboratory classification criteria. Seronegative APS patients are usually defined as patients with the clinical symptoms of APS but who test negative for aPL. The negativity to classic aPL criteria does not exclude the presence of other aPL. Several noncriteria aPL have been identified. Some noncriteria aPL are well studied, such as IgA aCL and aβ2GPI, the antiphosphatidylserine-prothrombin (aPS/PT) antibodies, and the antibodies against the domain I of beta2-glycoprotein I (aDI), both latter groups receiving more attention for their role in thrombotic events and pregnancy complications. Other noncriteria aPL that have been studied are antibodies against annexin V, prothrombin, phosphatidylethanolamine, phosphatidic acid, phosphatidylserine, phosphatidylinositol, vimentin-cardiolipin complex, anti-protein S/protein C. Measurement of some of these noncriteria aPL (aPS/PT, aDI) is useful in the laboratory work-out of APS in specific situations. We have to differentiate between patients who are positive for noncriteria aPL only, and patients who have both criteria and noncriteria aPL to enable us to study their role in the diagnosis or risk stratification of APS. The research on noncriteria aPL is continually developing as the clinical relevance of these antibodies is not yet fully clarified.

Non-criteria autoantibodies in antiphospholipid syndrome may be associated with underlying disease activity

BACKGROUND

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by persistent antiphospholipid antibodies (aPLs) with arterial and venous thrombosis and/or pregnancy morbidity. In recent years, several studies have highlighted the potential role of non-criteria aPL in diagnosing APS patients.

AIM

This study aimed to determine the association of the presence of non-criteria aPL antibodies to the clinical and laboratory features of patients with a diagnosis of APS.

METHODS

Eighty patients diagnosed with APS and under observation in the rheumatology clinic of Ankara City Hospital were assessed. Patient demographic and clinical features were meticulously recorded. Non-criteria antibodies tested in our center included antiphosphatidylserine IgA, antiphosphatidylserine IgM, beta 2 glycoprotein IgA, anti-cardiolipin IgA, antiphospholipid antibody IgG, and antiphospholipid antibody IgM. Antibodies from patients who were tested for at least one non-criteria antibody were documented.

RESULTS

Out of 80 patients, 55 (68.8%) were tested for at least one non-criteria antibody, and 29 of those patients (52.7%) tested positive for at least one non-criteria antibody. The antiphospholipid antibody IgM and the beta 2 glycoprotein IgA were the most commonly tested non-criteria antibodies. Patients with non-criteria antibody positivity had a higher frequency of Ds DNA positivity and low complement (62.0% vs. 35.0%, p = 0.042; 69.0% vs. 38.0%, p = 0.023), respectively. In addition, positivity for anti-cardiolipin IgG and b2 glycoprotein IgG was significantly higher in the group positive for non-criteria antibodies (79% vs. 31%, p ≤ 0.001; 72.0% vs. 19%, p ≤ 0.001). There was no significant difference between the clinical features of patients with at least one positivity for non-criteria antibodies and those without.

CONCLUSION

Systemic lupus erythematosus (SLE) is the most commonly associated disease with APS, being present in approximately 35% of cases [1]. Since the majority of the patient group in our study had APS that was secondary to SLE, non-criteria antibody positivity may be linked to the immunological activity of SLE. Large multicenter studies are necessary to investigate the clinical significance of isolated/combined positivity for criterion/non-criteria aPLs.

Profile and clinical relevance of non-criteria antiphospholipid antibodies in patients diagnosed with or highly suspected of APS

OBJECTIVE

This study investigates the positivity and relevance of non-criteria aPLs with clinical phenotypes in patients highly suspected of or diagnosed with APS.

METHODS

Outpatient cases were included from a prospectively maintained database, and patients were grouped into APS (n = 168), seronegative APS (SNAPS, n = 9), those meeting the diagnostic criteria for clinical events without laboratory results (only-event, n = 15), those that had aPL positivity without clinical manifestations (asymptomatic APA, n = 39), and healthy controls (n = 88). Criteria aPL results and APS-related clinical features were extracted. Sixteen non-criteria aPLs were tested and analysed.

RESULTS

LA, aCL and anti-β2 glycoprotein-I were positive in 84.5%, 61.3% and 74.4% of APS patients, and 61.5%, 59.0% and 74.4% of asymptomatic APA patients, respectively. In patients negative for criteria serological tests, 23 out of 24 were positive for at least one non-criteria aPL. Triple-positive patients also had significantly higher tests of some aPLs in comparison with other groups. Stroke was associated with anti-phosphatidyl-inositol (aPI) IgG and anti-phosphatidyl-glycerol (aPG) IgG. Late embryonic loss correlated with aPI IgM, and premature birth/eclampsia was associated with aPI IgG and aPG IgG. There were also positive associations between heart valve lesions and anti-phosphatidylserine-prothrombin (aPS/PT) IgM, APS nephropathy and anti-phosphatidyl-choline IgG or aPS/PT IgG, and livedo reticularis and anti-phosphatidyl-ethanolamine IgM.

CONCLUSION

The prevalence of non-criteria aPLs differed from diagnostic biomarkers in patients diagnosed with or suspected of APS. Detection of aPLs provided additive value in the evaluation of APS-related clinical manifestations.

Anti-phosphatidyl-serine/prothrombin (aPS/PT) antibodies are superior predictors of LAC presence and APS diagnoses: A single center study

BACKGROUND AND AIMS

Several non-criteria (NC) anti-phospholipid antibodies (APLA) have been proposed as candidates for antiphospholipid antibody syndrome (APS) diagnosis. The objectives of this study were 1) to determine the association of five different NC-APLA with positivity for Lupus anti-coagulant (LAC) and the criteria antibodies anti-cardiolipin (aCL) and anti-beta glycoprotein (aB2GPI), and 2) to assess the ability of NC-APLA to predict LAC presence and clinical APS diagnoses.

MATERIAL AND METHODS

Results from 486 patients tested for LAC and APLA were retrieved. Patients were grouped according to LAC and serology positivity into three groups: Single-positives (SP) for LAC, aCL or aB2GPI; Double-positives for aCL and aB2GPI; Triple-positives (TP) for LAC, aCL and aB2GPI. NC-ALPA titers were compared between LAC-positive and negative and APS and non-APS patients.

RESULTS

Forty-two of 486 patients were LAC-positive and 28 were diagnosed with APS. All criteria and NC-APLA titers were significantly higher in TP than SP patients. ROC analyses based on LAC status showed highest area under the curve (AUC, 95% CI) for aPS/PT IgG (0.75, 0.65-0.85) and aPS/PT IgM (0.73, 0.63-0.82). Based on APS diagnosis, aPS/PT IgM achieved highest AUC (0.87; 0.79-0.95).

CONCLUSION

Anti-phosphatidyl-serine/prothrombin (aPS/PT) antibodies are superior predictors of LAC presence and APS diagnoses.

A case of repeated in-stent restenosis of coronary artery as a primary manifestation of seronegative antiphospholipid antibody syndrome

BACKGROUND

Antiphospholipid antibody syndrome (APS) is a multisystemic autoimmune disorder which affects many organs or systems; however, coronary artery is relatively less frequently involved.

CASE PRESENTATION

A 65-year-old female with effort chest pain was hospitalized for unstable angina in Janurary, 2015. Coronary angiography revealed sub-total occlusion of proximal left anterior descending (LAD) coronary artery, where a drug-eluting stent was successfully deployed. The patient experienced multiple in-stent stenosis at LAD coronary artery and coronary artery bypass graft (CABG) surgery was advised. Subsequently, severe stenosis of left circumflex (LCX) coronary artery emerged, and the patient suffered persistent in-stent restenosis. Eventually, the patient was diagnosed with seronegative antiphospholipid antibody syndrome and salvaged by immunosuppressants.

CONCLUSIONS

Repeated in-stent restenosis could be a primary manifestation of seronegative antiphospholipid antibody syndrome, and suppression of autoimmune activity and inflammation other than purely coronary revascularization might be a better option.

Beyond the classics: The emerging value of anti-phosphatidylserine/prothrombin antibodies in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by the presence of antiphospholipid antibodies (aPLs), which can lead to thrombosis and pregnancy complications. Within the diverse range of aPLs, anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have gained significance in clinical practice. The detection of aPS/PT has proven valuable in identifying APS patients and stratifying their risk, especially when combined with other aPL tests like lupus anticoagulant (LA) and anti-β2-glycoprotein I (aβ2GPI). Multivariate analyses have confirmed aPS/PT as an independent risk factor for vascular thrombosis and obstetric complications, with its inclusion in the aPL score and the Global Anti-Phospholipid Syndrome Score (GAPSS) aiding in risk evaluation. However, challenges remain in the laboratory testing of aPS/PT, including the need for assay standardization and its lower sensitivity in certain patient populations. Further research is necessary to validate the clinical utility of aPS/PT antibodies in APS diagnosis, risk stratification, and management.

Preeclampsia and the Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is characterized by venous or arterial thrombosis and/or adverse pregnancy outcome in the presence of persistent laboratory evidence of antiphospholipid antibodies (aPLs). Preeclampsia complicates about 10-17% of pregnancies with APS. However, only early onset preeclampsia (<34 weeks of gestation) belongs to the clinical criteria of APS. The similarities in the pathophysiology of early onset preeclampsia and APS emphasize an association of these two syndromes. Overall, both are the result of a defective trophoblast invasion and decidual transformation at early gestation. Women with APS are at increased risk for prematurity; the reasons are mostly iatrogenic due to placental dysfunction, such as preeclampsia or FGR. Interestingly, women with APS have also an increased risk for preterm delivery, even in the absence of FGR and preeclampsia, and therefore it is not indicated but spontaneous. The basic treatment of APS in pregnancy is low-dose aspirin and low-molecular-weight heparin. Nevertheless, up to 20-30% of women develop complications at early and late gestation, despite basic treatment. Several additional treatment options have been proposed, with hydroxychloroquine (HCQ) being one of the most efficient. Additionally, nutritional interventions, such as intake of vitamin D, have shown promising beneficial effects. Curcumin, due to its antioxidant and anti-inflammatory properties, might be considered as an additional intervention as well.

Criteria and Non-Criteria Antiphospholipid Antibodies in Antiphospholipid Syndrome: How Strong Are They Correlated?

The place of non-criteria antiphospholipid antibodies (aPLs) in the diagnosis of antiphospholipid syndrome (APS) is still debatable. The aim of this research was to evaluate the correlations between the titres of non-criteria aPLs (anti-phosphatidylethanolamine (aPE), anti-phosphatidylserine (aPS), and anti-prothrombin (aPT) antibodies), and the ones of the already studied criteria aPLs (anti-cardiolipin (aCL) and anti-β2 glycoprotein I-aβ2GPI antibodies). Altogether, 72 APS (30 primary and 42 secondary) patients were included in our study. High correlation coefficients (rs) were found between aPS IgM and aCL IgM, overall (0.77, p < 0.01), as well as in the primary (0.81, p < 0.01), and secondary (0.75, p < 0.01) APS subgroups. Low or statistically insignificant correlations were observed between IgG/IgM isotypes of aPT and aCL, or aβ2GPI, in the entire study population, and when evaluating the subgroups. Therefore, moderate correlations were mainly identified between the tested non-criteria antibodies and the criteria ones, suggesting little added value for the use of the tested non-criteria aPLs, with the exception of aPT, which seems to have different kinetics and might be a promising APS diagnostic tool.

Anti-β2GPI-domain I antibody is associated with extra-criteria manifestations in a large prospective antiphospholipid syndrome cohort in China

BACKGROUND

Anti-β2GPI-domain I (β2GPI-DI) antibody is pathogenic in patients with antiphospholipid syndrome (APS), but its additional clinical associations and diagnostic value are controversial.

METHODS

A total of 378 patients were included, of which 119 patients diagnosed with primary APS, 50 with APS secondary to SLE (SAPS group), 209 with SLE without APS (SLE group). Serum anti-β2GPI-DI IgG was measured using chemiluminescent immunoassay. Extra-criteria manifestations were analysed, including thrombocytopenia, autoimmune haemolytic anaemia, valvular lesions, APS nephropathy and non-vascular neurological manifestations.

RESULTS

In 169 patients with APS, 55 (32.5%) were positive for anti-β2GPI-DI IgG, accounting for 77.5% of those with anti-β2GPI IgG positivity. It is shown that 96.4% of those with anti-β2GPI-DI IgG also showed triple positivity in classic antiphospholipid antibodies (aPLs). The positivity of anti-β2GPI-DI IgG was significantly associated with recurrent thrombosis before APS diagnosis (p=0.015), microvascular thrombosis (p=0.038), but not with pregnancy morbidity (PM). Notably, patients with extra-criteria manifestations showed significantly higher positivity (p=0.001) and titres (p<0.001) in anti-β2GPI-DI IgG, especially for thrombocytopenia and APS nephropathy. In multivariable analysis, anti-β2GPI-DI IgG positivity (OR 2.94, 95% CI 1.29 to 6.70), secondary APS, arterial hypertension and Coombs' test positivity independently predicted extra-criteria manifestations (C-index 0.83, 95% CI 0.77 to 0.90). After a median follow-up of 25 months, patients with anti-β2GPI-DI IgG also showed a tendency of more extra-criteria events, but not thrombotic events. Anti-β2GPI-DI was positive among 8.1% of the SLE controls, and showed high specificity (91.9%) in diagnosing SAPS among patients with SLE as compared with classic aPLs.

CONCLUSION

Anti-β2GPI-DI IgG was associated with extra-criteria manifestations in patients with APS. Further studies are warranted to validate its predictive values and potential role in daily practice.

High-throughput sequencing technology facilitates the discovery of novel biomarkers for antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by arterial and venous thrombosis and/or morbid pregnancy, accompanied by persistent antiphospholipid antibody (aPL) positivity. However, due to the complex pathogenesis of APS and the large individual differences in the expression of aPL profiles of patients, the problem of APS diagnosis, prognosis judgment, and risk assessment may not be solved only from the antibody level. It is necessary to use new technologies and multiple dimensions to explore novel APS biomarkers. The application of next-generation sequencing (NGS) technology in diseases with a high incidence of somatic mutations, such as genetic diseases and tumors, has been very mature. Thus, we try to know the research and application progress of APS by NGS technology from genome, transcriptome, epigenome and other aspects. This review will describe the related research of NGS technology in APS and provide more reference for the deep understanding of APS-related screening markers and disease pathogenesis.

Extra-criteria antiphospholipid antibodies in patients with small vessel brain lesions and clinical manifestations associated with antiphospholipid syndrome

OBJECTIVES

Neurological manifestations compatible with small vessel brain lesions (SVBL), such as migraine, cognitive impairment, seizures, and transverse myelitis, may be related to antiphospholipid syndrome (APS) and patients could need APS therapies even though they do not fit into thrombosis or obstetric morbidity. Furthermore, extra-criteria antiphospholipid antibodies (aPL) provide an increase in sensitivity in patients with clinical manifestations related to APS but negative for IgG/IgM anticardiolipin (aCL), anti-β2 glycoprotein I (aβ2GPI), and lupus anticoagulant, which are the antibodies included in the classification criteria for APS.

METHODS

We determined extra-criteria aPL in 65 SVBL patients with neurological traits and Magnetic Resonance Imaging suggestive of APS but negative for APS classification criteria, 47 of whom were prospectively followed and tested over three years. A group of 95 patients with autoimmune diseases (AD) but without clinical traits of APS was also studied.

RESULTS

A persistent presence of extra-criteria aPL was detected in 27.7% of patients: 12.77% IgM anti- prothrombin (PT), 6.38% IgG anti-PT, 6.38% IgM anti-phosphatidylethanolamine (PE), 4.26% IgA aβ2GPI, 2.13% IgG anti-phosphatidylserine/prothrombin (PS/PT) and 2.13% IgM anti-PS/PT. There was a tendency towards a higher prevalence of these aPL in SVBL patients than in AD - especially for IgA aβ2GPI - and a lack of IgG aPS/PT positivity in the AD group. We found no SVBL patient positive for IgA aCL, IgG anti-PE, annexin V, or aβ2GPI domain I.

CONCLUSIONS

Extra-criteria aPL can improve sensitivity for APS diagnosis in patients with SVBL, especially IgA aβ2GPI and IgG anti-PS/PT antibodies.

Laboratory Testing for Non-criteria Antiphospholipid Antibodies: Anti-phosphatidylserine/Prothrombin Antibodies (aPS/PT)

Since the discovery that antiphospholipid antibodies (aPL) bind to a cofactor at the phospholipid membrane, the proteins beta-2-glycoprotein I (β2GPI) and prothrombin seemed to be the antigens of importance in the antiphospholipid syndrome (APS). Anti-β2GPI antibodies (aβ2GPI) were soon included in the classification criteria, while anti-prothrombin antibodies (aPT) are still regarded as "non-criteria" aPL. Evidence is accumulating that antibodies against prothrombin are clinically relevant and closely associated with APS and the presence of lupus anticoagulant (LA). Among the non-criteria aPL, anti-phosphatidylserine/prothrombin antibodies (aPS/PT) are one of the most frequently studied aPL. More and more studies illustrate the evidence of the pathogenic capacity of these antibodies. aPS/PT IgG and IgM are associated with arterial and venous thrombosis, show an overlap with LA presence, and are frequently present in triple-positive patients, regarded as patients at highest risk for APS-related clinical symptoms. Moreover, the association of aPS/PT with thrombosis increases with higher titers, confirming that presence of aPS/PT consolidates the risk. So far, the added value of aPS/PT on top of the criteria aPL to diagnose APS is not clear with opposing findings in literature. Described in this chapter is the procedure for detecting these antibodies with a commercial ELISA, which can be used to determine the presence of IgG and IgM aPS/PT in human samples. Additionally, general guidelines that will facilitate optimal performance of the aPS/PT assay will be provided.

Prevalence and diagnostic value of non-criteria antiphospholipid antibodies for antiphospholipid syndrome in Chinese patients

Background

The presence of antiphospholipid antibodies (aPLs) plays a pivotal role in the pathogenesis of antiphospholipid antibody syndrome (APS). This study aimed to examine the diagnostic value of a set of non-criteria aPLs and their relevance with APS-related criteria and extra-criteria manifestations.

Methods

From a prospectively constructed database, consecutive APS patients consisting of 114 primary APS (PAPS group), 54 with APS secondary to SLE (SAPS group), 9 seronegative APS (SNAPS), as well as 209 patients with systemic lupus erythematosus (SLE) and 88 healthy controls were included in this study. Levels of criteria aPLs, baseline information, and APS-related criteria and extra-criteria features were extracted from the database. Serum levels of non-criteria aPLs including aPC IgG/IgM, aPI IgG/IgM, aPE IgG/IgM/IgA, aPG IgG/IgM/IgA, anti-phosphatidic acid (aPA) IgG/IgM, aSM IgG/IgM, and aPS/PT IgG/IgM were analyzed with AESKULISA® ELISA Test Kits.

Results

The addition of aPC IgG/M, aPI IgG/M, aPE IgG/M/A, aSM IgG/M, and aPA IgG/M to aCL or aβ2GPI IgG/M could significantly increase diagnostic sensitivity and accuracy. A significant difference between PAPS or SAPS and HC was presented in all non-criteria aPLs except for aSM IgM and aPG IgA. Eight out of nine SNAPS patients were positive for at least 1 aPL. Pregnancy morbidity was associated with aSM IgM (r = 0.22) and aSM IgG (r = 0.15). Pre-eclampsia or premature birth was associated with aSM IgG (r = 0.16), aPI IgG (r = 0.22), aPC IgG (r = 0.16), and aPG IgG (r = 0.18). Stroke was associated with aPI IgG (r = 0.2). The clinical association was also observed in DVT with aPS/PT IgG (r = 0.17). Valve lesion was positively associated with aSM IgM (Fisher test p = 0.039), APS nephropathy was associated with aPC IgG (OR 3.797), and livedo reticularis was associated with aPE IgM (OR 15.391).

Conclusion

Additional detection of non-criteria aPLs including aPC IgG/M, aPE IgG/M/A, aPI IgG/M, aSM IgG/M, and aPA IgG/M could assist in APS diagnosis. The positivity of certain aPLs was statistically associated with both criteria and extra-criteria APS clinical manifestations.

Non-criteria antiphospholipid antibodies in antiphospholipid syndrome: Diagnostic value added

Objective

Non-criteria antiphospholipid antibodies (aPLs) increase the diagnostic value for antiphospholipid syndrome (APS) and contribute to better recognition of seronegative APS (SNAPS). However, the clinical utility and the diagnostic value of non-criteria aPLs are inconsistent. This study aimed to investigate the prevalence and clinical significance of 7 non-criteria aPLs in a large APS cohort.

Methods

Seven non-criteria aPLs, including anti-phosphatidylserine/prothrombin (aPS/PT) antibodies IgG/IgA/IgM, anti-phosphatidylethanolamine antibodies (aPE) IgG/IgA/IgM, anti-Annexin V antibodies (aAnnexinV) IgG/IgA/IgM, anti-phosphatidylserine antibodies (aPS) IgM, aPS IgG, antibodies directed against a mixture of phospholipids (APhL) IgG, and APhL IgM were tested among 175 patients with APS, 122 patients with other autoimmune diseases (as disease controls), and 50 healthy controls.

Results

In the present study, the highest prevalence of non-criteria aPLs was seen in aAnnexinV (58.86%). APhL IgG and aPS IgM showed the highest specificity (95.35%) and aPS/PT showed the highest Youden index (0.3991) for the diagnostic value of APS. The aAnnexinV also showed the highest prevalence in SNAPS (43.3%), followed by APhL IgM (21.7%), aPE (16.7%) and aPS/PT (16.7%). APhL IgG, aPS/PT, and aPS IgG showed positive association with thrombotic events in APS patients [APhL IgG: odds ratio (OR) = 2.26, 95% confidence interval (CI) 1.18-4.34, p = 0.013; aPS/PT: OR = 2.48, 95% CI: 1.32-4.69, p = 0.004; aPS IgG: OR = 1.90, 95% CI 1.01-3.60, p = 0.046; respectively). The inclusion of the non-criteria aPLs increased the accuracy of APS diagnosis from 65.7% to 87.4%.

Conclusion

Our data provide evidence that adding the non-criteria aPLs can improve the diagnostic accuracy in APS. APhL IgG, aPS/PT, and aPS IgG may be potential biomarkers to predict the risk of thrombosis in APS.

The Role of Autoantibody Testing in Modern Personalized Medicine

Personalized medicine (PM) aims individualized approach to prevention, diagnosis, and treatment. Precision Medicine applies the paradigm of PM by defining groups of individuals with akin characteristics. Often the two terms have been used interchangeably. The quest for PM has been advancing for centuries as traditional nosology classification defines groups of clinical conditions with relatively similar prognoses and treatment options. However, any individual is characterized by a unique set of multiple characteristics and therefore the achievement of PM implies the determination of myriad demographic, epidemiological, clinical, laboratory, and imaging parameters. The accelerated identification of numerous biological variables associated with diverse health conditions contributes to the fulfillment of one of the pre-requisites for PM. The advent of multiplex analytical platforms contributes to the determination of thousands of biological parameters using minute amounts of serum or other biological matrixes. Finally, big data analysis and machine learning contribute to the processing and integration of the multiplexed data at the individual level, allowing for the personalized definition of susceptibility, diagnosis, prognosis, prevention, and treatment. Autoantibodies are traditional biomarkers for autoimmune diseases and can contribute to PM in many aspects, including identification of individuals at risk, early diagnosis, disease sub-phenotyping, definition of prognosis, and treatment, as well as monitoring disease activity. Herein we address how autoantibodies can promote PM in autoimmune diseases using the examples of systemic lupus erythematosus, antiphospholipid syndrome, rheumatoid arthritis, Sjögren syndrome, systemic sclerosis, idiopathic inflammatory myopathies, autoimmune hepatitis, primary biliary cholangitis, and autoimmune neurologic diseases.

Added value of antiphosphatidylserine/prothrombin antibodies in the workup of thrombotic antiphospholipid syndrome: Communication from the ISTH SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies

BACKGROUND

Diagnosis of antiphospholipid syndrome (APS) requires persistent presence of lupus anticoagulant (LAC), anticardiolipin (aCL) IgG/IgM, or anti-β2 glycoprotein I (aβ2GPI) IgG/IgM antibodies. Other antiphospholipid antibodies (aPL) such as antiphosphatidylserine/prothrombin antibodies (aPS/PT) are promising in assessment of thrombotic APS (TAPS).

AIM

To evaluate the added value of aPS/PT IgG and IgM in TAPS.

MATERIAL AND METHODS

aPS/PT IgG/IgM, aCL IgG/IgM, aβ2GPI IgG/IgM, and LAC were determined in 757 patients (TAPS and controls). aPS/PT cut-off values were calculated, and aPS/PT titers and positivity were compared between TAPS and controls, type of thrombosis, and antibody profiles. Likelihood ratios (LR), odds ratios (OR), and aPL score were determined.

RESULTS

aPS/PT IgG and IgM were associated with TAPS and triple positivity. In-house calculated cut-offs were higher for IgM (43 units), compared to manufacturer's cut-off (30 units). Thresholds of 90 (IgG) and 200 (IgM) units were determined as high-titer cut-off. Higher aPS/PT titers were observed in triple positive patients and showed higher LR and OR for TAPS. aPS/PT was independently associated with TAPS when adjusted for aCL/aβ2GPI, but not when adjusted for LAC. In isolated LAC positive patients, aPS/PT was positive in 27.1% TAPS patients and in 77.3% patients with autoimmune disease. Diagnostic value of aPL score did not differ with and without including aPS/PT.

CONCLUSION

aPS/PT positivity, especially with high antibody titer, is associated with TAPS diagnosis. Analysis on top of current laboratory criteria is not essential in TAPS diagnosis, but aPS/PT could be useful in patients with thrombosis and a double positive aPL profile (aCL+/aβ2GPI+).

Comparison of non-criteria antiphospholipid syndrome with definite antiphospholipid syndrome: A systematic review

Objectives

Patients with laboratory or clinical manifestations suggestive of antiphospholipid syndrome (APS) but not fulfilling the classification criteria constitute a clinical challenge. This study aims to compare non-criteria APS (NC-APS) with definite APS in terms of clinical manifestations, therapies, and outcomes.

Methods

A systematic review of observational studies comparing definite and NC-APS was performed searching four electronic databases. Data on clinical manifestations, therapies and clinical outcomes was extracted.

Results

Sixteen studies, assessing a total of 3,798 participants, were included. Seven out of 10 studies found no significant difference in the prevalence of arterial or venous thrombosis between definite and NC-APS, with two studies on seronegative APS also finding no difference in thrombosis recurrence. Seven out of 12 studies found no significant difference in the prevalence of obstetric manifestations between groups, with the remaining exhibiting conflicting results. In 9 studies comparing treatment frequency in obstetric patients, all but one described similar treatment frequency, with the percentage of NC-APS treated during pregnancy ranging from 26% to 100%. In 10 studies comparing pregnancy outcomes of NC-APS versus definite APS, 7 found similar successful pregnancies/live births. Additionally, 5 studies described improvement of live births in both groups with treatment, with three signalling aspirin monotherapy as efficacious as combination therapy in NC-APS.

Conclusion

This review hints at an absence of marked differences in most evaluated parameters between definite and NC-APS, emphasizing the value of a more active follow-up of these patients. The low-quality available evidence highlights the need for well-defined NC-APS populations in future studies.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero, identifier CRD42020210674.

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.

[Contribution of antiphosphatidylserine/prothrombin (anti-PS/PT) antibody detection in the diagnosis and management of antiphospholipid syndrome (APS)]

Antiphospholipid syndrome (APS) is an autoimmune disease and one of the most common causes of acquired thrombophilia. It is characterised by the occurrence of thrombotic or obstetric events associated with the presence of persistent antiphospholipid antibodies. The diagnosis can be challenging, particularly because some biological tests can be disturbed by anticoagulant treatment or inflammation. In the recent years, new antiphospholipid antibodies, including anti-phosphatidylserine/prothrombin antibodies (anti-PS/PT), have emerged but their clinical significance and causality remain uncertain. Biologically, several studies have found a strong correlation between the presence of lupus anticoagulant (LA) and anti-PS/PT antibodies. Clinically, the presence of anti-PS/PT antibodies is associated with an increased risk of thrombosis and obstetric complications. There is also an association with thrombocytopenia, suggesting that the presence of anti-PS/PT antibodies may be associated with more severe clinical APS. Among seronegative APS patients, 6-17% of patients are positive for anti-PS/PT antibodies. This might influence the therapeutic management of patients. This article aims to provide an update on contribution of anti-PS/PT antibodies detection for the diagnosis and management of APS.

Solid Phase Assays for Antiphospholipid Antibodies

The diagnosis of antiphospholipid syndrome (APS) relies on the detection of circulating antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are the laboratory criteria if persistently present over time. As aCL and aβ2GPI are two out of the three laboratory criteria, the detection of aPL by solid phase assays is an essential step in the diagnosis of APS. Advancement has been made to resolve some of the methodological challenges of aCL and aβ2GPI assays by providing guidelines how to measure aPL, as well as to gain a better understanding of their diagnostic role. However, solid phase assays for aCL and aβ2GPI still show substantive inter-assay differences, resulting in disagreement concerning positive/negative results, but also differences in titer of antibodies. This hampers the semiquantitative classification into low-medium-high positivity. The non-criteria aPL, such as antibodies against the domain one of β2GPI and anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have roles in confirming the risk in APS, and can be useful, especially in patients with incomplete antibody profiles.

Laboratory Diagnosis of Antiphospholipid Syndrome: Insights and Hindrances

Diagnosis of antiphospholipid syndrome (APS) requires the presence of a clinical criterion (thrombosis and/or pregnancy morbidity), combined with persistently circulating antiphospholipid antibodies (aPL). Currently, laboratory criteria aPL consist of lupus anticoagulant (LAC), anticardiolipin antibodies (aCL) IgG/IgM, and anti-β2 glycoprotein I antibodies (aβ2GPI) IgG/IgM. Diagnosis and risk stratification of APS are complex and efforts to standardize and optimize laboratory tests have been ongoing since the initial description of the syndrome. LAC detection is based on functional coagulation assays, while aCL and aβ2GPI are measured with immunological solid-phase assays. LAC assays are especially prone to interference by anticoagulation therapy, but strategies to circumvent this interference are promising. Alternative techniques such as thrombin generation for LAC detection and to estimate LAC pathogenicity have been suggested, but are not applicable yet in routine setting. For aCL and aβ2GPI, a lot of different assays and detection techniques such as enzyme-linked immunosorbent and chemiluminescent assays are available. Furthermore, a lack of universal calibrators or standards results in high variability between the different solid-phase assays. Other non-criteria aPL such as anti-domain I β2 glycoprotein I and antiphosphatidylserine/prothrombin antibodies have been suggested for risk stratification purposes in APS, while their added value to diagnostic criteria seems limited. In this review, we will describe laboratory assays for diagnostic and risk evaluation in APS, integrating applicable guidelines and classification criteria. Current insights and hindrances are addressed with respect to both laboratory and clinical implications.

Profile of antiphospholipid antibodies in HIV-infected and HIV-uninfected women with a history of thrombosis

INTRODUCTION

Increased antiphospholipid antibodies (aPL) have been described in human immunodeficiency virus (HIV) infection. However, the association between aPL and the increased risk of thrombosis in HIV requires further clarification.

METHODS

We reviewed the medical records of 215 consecutive women with a history of thrombosis and/or obstetric complications (158 HIV-uninfected and 57 HIV-infected) between July 2017 and March 2021. Participants (n = 215) without clinical criteria manifestations for antiphospholipid syndrome were included as matched controls. Testing for lupus anticoagulant (LAC), anticardiolipin (aCL) and anti-beta2-glycoprotein1 (aβ2GP1) IgM and IgG was performed.

RESULTS

Thirty-two (10.1%) HIV-uninfected and 15 (13.2%) HIV-infected participants were positive at baseline for one of the five criteria aPL, with no statistically significant difference. The profile of the HIV-infected participants with thrombosis (n = 11) included LAC in 15.8%, aCL IgG in 3.5% and aβ2GP1 IgG in 1.8%. In contrast, the HIV-infected controls (n = 4), included aCL IgM in 1.8% and aβ2GP1 IgM in 5.3%. Only LAC was significantly associated with thrombosis (p < 0.003). On repeat testing, in a HIV-infected sub-population, 2/7 with thrombosis were positive, while 3/3 controls tested negative.

CONCLUSION

In contrast to earlier reports, the prevalence and expression of aPL in HIV-infected women with a history of thrombosis in the present study, in the era of antiretroviral therapy, were similar to HIV-uninfected women. Baseline LAC positivity was associated with a significantly increased risk for thrombosis in HIV. Future studies are recommended to explore additional coagulation abnormalities in HIV.

Pathogenesis, Diagnosis and Management of Obstetric Antiphospholipid Syndrome: A Comprehensive Review

Antiphospholipid syndrome is an autoimmune disorder characterized by vascular thrombosis and/or pregnancy morbidity associated with persistent antiphospholipid antibody positivity. Cases fulfilling the Sydney criteria for obstetric morbidity with no previous thrombosis are known as obstetric antiphospholipid syndrome (OAPS). OAPS is the most identified cause of recurrent pregnancy loss and late-pregnancy morbidity related to placental injury. Cases with incomplete clinical or laboratory data are classified as obstetric morbidity APS (OMAPS) and non-criteria OAPS (NC-OAPS), respectively. Inflammatory and thrombotic mechanisms are involved in the pathophysiology of OAPS. Trophoblasts, endothelium, platelets and innate immune cells are key cellular players. Complement activation plays a crucial pathogenic role. Secondary placental thrombosis appears by clot formation in response to tissue factor activation. New risk assessment tools could improve the prediction of obstetric complication recurrences or thromboses. The standard-of-care treatment consists of low-dose aspirin and prophylactic low molecular weight heparin. In refractory cases, the addition of hydroxychloroquine, low-dose prednisone or IVIG improve pregnancy outcomes. Statins and eculizumab are currently being tested for treating selected OAPS women. Finally, we revisited recent insights and concerns about the pathophysiology, diagnosis and management of OAPS.

Role of antiphospholipid antibodies in the diagnosis of antiphospholipid syndrome

The diagnosis of antiphospholipid syndrome (APS) relies on the detection of antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LA), anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are included as laboratory criteria, if persistently present. LAC measurement remains a complicated procedure with many pitfalls and interfered by anticoagulant therapy. Solid-phase assays for aCL and aβ2GPI show interassay differences. These methodological issues make the laboratory diagnosis of APS challenging. In the interpretation of aPL results, antibody profiles help in identifying patients at risk. Other aPL, such as antibodies against the domain I of beta2-glycoprotein (aDI) and antiphosphatidylserine-prothrombin (aPS/PT) antibodies have been studied in the last years and may be useful in risk stratification of APS patients. Because of the methodological shortcomings of immunological and clotting assays, these non-criteria aPL may be useful in patients with incomplete antibody profiles to confirm or exclude the increased risk profile. This manuscript will focus on the laboratory aspects, the clinical relevance of assays and interpretation of aPL results in the diagnosis of APS.

•

The presence of antiphospholipid antibodies (aPL) define the diagnosis of the antiphospholipid syndrome (APS).

•

Laboratory criteria are lupus anticoagulant, anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG/IgM.

•

Lupus anticoagulant measurement, as well as solid phase assays for aCL and aβ2GPI, show methodological challenges.

•

Antibodies against domain I of β2GPI (aDI) and antiphosphatidylserine-prothrombin (aPS/PT) antibodies are non-criteria aPL.

•

aDI and aPS/PT may be useful in risk stratification of APS patients.

Antiphospholipid-negative Sneddon's syndrome: A comprehensive overview of a rare entity

The term Sneddon's syndrome (SS) has been used since 1965 to describe a vasculopathy characterized by a combination of cerebrovascular disease with livedo racemosa. SS may be classified as antiphospholipid+ (aPL+) or antiphospholipid- (aPL-). Little is known about aPL- SS; in this review we describe the epidemiology and pathogenesis of aPL- SS, as well as the clinical and histologic features. We discuss recent findings in terms of neurologic and cardiac involvement. Moreover, differential diagnoses of conditions that may present with both livedo racemosa and stroke are discussed. Finally, we discuss real-life practical issues such as the initial investigations to be performed, long-term follow-up, and therapeutic management of aPL- SS patients.

Anti-Phosphatidylserine/Prothrombin Antibodies at Two Points: Correlation With Lupus Anticoagulant and Thrombotic Risk

Antibodies to phospholipids (aPL) and associated proteins are a hallmark in the diagnosis of anti-phospholipid syndrome (APS). Those included in the classification criteria are the lupus anticoagulant (LA) and the IgG and IgM isotypes of anticardiolipin (aCL) and anti-beta-2 glycoprotein I (β2GPI) antibodies. Non-classification criteria markers such as autoantibodies that recognize the phosphatidylserine/prothrombin (aPS/PT) complex have been proposed as biomarkers for APS. Studies of aPS/PT antibodies have shown a strong correlation to clinical manifestations and LA. We aimed to study the value and the persistence of aPS/PT IgG and IgM antibodies in a cohort of consecutive patients with clinical suspicion of APS and their utility as thrombotic risk markers. Our study, with 103 patients, demonstrates that persistently positive results for aPS/PT IgG antibodies were significantly associated with APS classification, thrombosis, triple aPL positivity, LA positive result, and the Global APS Score (GAPSS) > than 9 points (p < 0.01, for each condition). On the other hand, no association was seen with pregnancy morbidity (p = 0.56) and SLE (p = 0.07). Persistence of aPS/PT antibodies, defined according to the current laboratory classification criteria, likely improves the diagnosis and clinical assessment of patients with APS.

Evaluation of the Diagnostic Value of Non-criteria Antibodies for Antiphospholipid Syndrome Patients in a Chinese Cohort

Objective

Although specific anti-phospholipid antibodies (aPLs) have been used in the diagnosis of the antiphospholipid syndrome (APS) for years, new biomarkers are required to increase its diagnostic and risk-predictive power. This study aimed to explore the value of several non-criteria aPLs in a Chinese cohort.

Methods

A total of 312 subjects, namely, 100 patients diagnosed with primary APS, 51 with APS secondary to SLE, 71 with SLE, and 90 healthy controls, were recruited. Serum anticardiolipin (aCL) IgG/IgM/IgA, anti-β2-glycoprotein I (aβ2GPI) IgG/IgM/IgA, anti-phosphatidylserine/prothrombin antibodies (aPS/PT) IgG/IgM, and anti-annexin A5 antibodies (aAnxV) IgG/IgM were tested using ELISA kits.

Results

Of the total number of patients, 30.46% and 6.62% with APS were positive for aCL or aβ2GPI IgA, respectively, while 39.07% and 24.50% were positive for aAnxV or aPS/PT for at least one antibody (IgG or IgM). The addition test of aCL IgA and aAnxV IgM assists in identifying seronegative APS patients, and IgG aPS/PT was linked to stroke.

Conclusion

Detection of aCL IgA, aβ2GPI IgA, aAnxV IgG/M, and aPS/PT IgG/M as a biomarker provides additive value in APS diagnosis and would help in risk prediction for APS patients in medical practice.

Obstetrical outcome and treatments in seronegative primary APS: data from European retrospective study

OBJECTIVE

To compare characteristics, pregnancies and treatments during pregnancies of seronegative and seropositive antiphospholipid syndrome (APS), to analyse factors associated with obstetrical outcome.

PATIENTS AND METHODS

Inclusion criteria were: (1) thrombotic and/or obstetrical APS (Sydney criteria); (2) absence of conventional antiphospholipid antibodies (APL); (3) at least one persistent non-conventional APL among IgA anticardiolipin antibodies, IgA anti-B2GPI, anti-vimentin G/M, anti-annexin V G/M, anti-phosphatidylethanolamine G/M and anti-phosphatidylserine/prothrombin G/M antibodies. The exclusion criteria were: (1) systemic lupus erythematosus ( SLE) or SLE-like disease; and (2) other connective tissue disease.

RESULTS

A total of 187 women (mean 33±5 years) with seronegative APS were included from 14 centres in Austria, Spain, Italy, Slovenia and France and compared with 285 patients with seropositive APS. Seronegative APS has more obstetrical rather than thrombotic phenotypes, with only 6% of venous thrombosis in comparison to seropositive APS. Cumulative incidence of adverse obstetrical events was similar in seronegative and seropositive APS patients, although higher rates of intrauterine deaths (15% vs 5%; p=0.03), of preeclampsia (7% vs 16%, p=0.048) and lower live birth term (36±3 vs 38±3 weeks of gestation; p=0.04) were noted in seropositive APS. The cumulative incidence of adverse obstetrical events was significantly improved in treated versus untreated seronegative APS (log rank<0.05), whereas there was no difference between patients who received aspirin or aspirin-low-molecular weighted heparin combination.

CONCLUSION

Several non-criteria APL can be detected in patients with clinical APS features without any conventional APL, with various rates. The detection of non-criteria APL and thus the diagnosis of seronegative APS could discuss the therapeutic management similar to seropositive APS, but well-designed controlled studies are necessary.

Antiprothrombin antibodies induce platelet activation: A possible explanation for anti-FXa therapy failure in patients with antiphospholipid syndrome?

BACKGROUND

Arterial and venous thrombosis are both common in antiphospholipid syndrome (APS). Recent studies have shown that anti-factor Xa (FXa) therapy in APS patients leads to a greater number of patients with arterial thrombosis than with warfarin. We hypothesize that this may be due to the lowering of prothrombin levels by warfarin.

OBJECTIVES

To investigate whether antiprothrombin antibodies induce platelet aggregation and to identify the platelet receptors involved. A second aim was to investigate the effect of reduced prothrombin levels on antiprothrombin antibody-induced platelet aggregation.

METHODS

Enzyme-linked immunosorbent assays were performed to measure binding of antiprothrombin antibodies to prothrombin fragment 1+2 and prothrombin. Platelet aggregation assays in washed platelets were performed. FcγRIIA was immunoprecipitated and tyrosine-phosphorylated FcγRIIA was measured by western blot.

RESULTS

The antiprothrombin antibodies 28F4 and 3B1 had lupus anticoagulant (LAC) activity and caused platelet aggregation in the presence of Ca2+ and prothrombin. Antiprothrombin antibodies without LAC activity did not activate platelets. Inhibition of Syk and Src kinases and FcγRIIA blocked platelet aggregation. Fab and F(ab')2 fragments of 28F4 were unable to induce platelet aggregation. Immunoprecipitations showed that whole 28F4 immunoglobulin G induced tyrosine phosphorylation of FcγRIIA. Platelet aggregation was significantly reduced when prothrombin levels were reduced from 1 µM to 0.2 µM.

CONCLUSIONS

Antiprothrombin antibodies with LAC activity are able to activate platelets via FcγRIIA. Decreased prothrombin levels resulted in less antiprothrombin antibody-mediated platelet aggregation. This may explain the lower incidence of arterial thrombosis in patients treated with warfarin than with anti-FXa therapy.

Microparticles: An Alternative Explanation to the Behavior of Vascular Antiphospholipid Syndrome

Antiphospholipid syndrome is an autoimmune disease characterized by the persistent presence of antiphospholipid antibodies, along with occurrence of vascular thrombosis and pregnancy morbidity. The variety of antiphospholipid antibodies and their related mechanisms, as well as the behavior of disease in wide groups of patients, have led some authors to propose a differentiation of this syndrome into two independent entities: vascular and obstetric antiphospholipid syndrome. Thus, previous studies have discussed whether specific autoantibodies may be responsible for this differentiation or, in contrast, how the same antibodies are able to generate two different clinical presentations. This discussion is yet to be settled. The capability of serum IgG from patients with vascular thrombosis to trigger the biogenesis of endothelial cell-derived microparticles in vitro is one of the previously discussed differences between the clinical entities of antiphospholipid syndrome. These vesicles constitute a prothrombotic mechanism as they can directly lead to clot activation in murine models and recalcified human plasma. Nevertheless, other indirect mechanisms by which microparticles can spread a procoagulant phenotype could be critical to understanding their role in antiphospholipid syndrome. For this reason, questions regarding the cargo of microparticles, and the signaling pathways involved in their biogenesis, are of interest in attempting to explain the behavior of this autoimmune disease.

Lupus anticoagulant single positivity at acute phase is not associated with venous thromboembolism or in-hospital mortality in COVID-19

Objective

The clinical relevance of antiphospholipid antibodies (aPLs) in COVID‐19 is controversial. This study was undertaken to investigate the prevalence and prognostic value of conventional and nonconventional aPLs in patients with COVID‐19.

Methods

This was a multicenter, prospective observational study in a French cohort of patients hospitalized with suspected COVID‐19.

Results

Two hundred forty‐nine patients were hospitalized with suspected COVID‐19, in whom COVID‐19 was confirmed in 154 and not confirmed in 95. We found a significant increase in lupus anticoagulant (LAC) positivity among patients with COVID‐19 compared to patients without COVID‐19 (60.9% versus 23.7%; P < 0.001), while prevalence of conventional aPLs (IgG and IgM anti–β₂‐glycoprotein I and IgG and IgM anticardiolipin isotypes) and nonconventional aPLs (IgA isotype of anticardiolipin, IgA isotype of anti‐β₂‐glycoprotein I, IgG and IgM isotypes of anti–phosphatidylserine/prothrombin, and IgG and IgM isotypes of antiprothrombin) was low in both groups. Patients with COVID‐19 who were positive for LAC, as compared to patients with COVID‐19 who were negative for LAC, had higher levels of fibrinogen (median 6.0 gm/liter [interquartile range 5.0–7.0] versus 5.3 gm/liter [interquartile range 4.3–6.4]; P = 0.028) and C‐reactive protein (CRP) (median 115.5 mg/liter [interquartile range 66.0–204.8] versus 91.8 mg/liter [interquartile range 27.0–155.1]; P = 0.019). Univariate analysis did not show any association between LAC positivity and higher risks of venous thromboembolism (VTE) (odds ratio 1.02 [95% confidence interval 0.44–2.43], P = 0.95) or in‐hospital mortality (odds ratio 1.80 [95% confidence interval 0.70–5.05], P = 0.24). With and without adjustment for CRP level, age, and sex, Kaplan‐Meier survival curves according to LAC positivity confirmed the absence of an association with VTE or in‐hospital mortality (unadjusted P = 0.64 and P = 0.26, respectively; adjusted hazard ratio 1.13 [95% confidence interval 0.48–2.60] and 1.80 [95% confidence interval 0.67–5.01], respectively).

Conclusion

Patients with COVID‐19 have an increased prevalence of LAC positivity associated with biologic markers of inflammation. However, LAC positivity at the time of hospital admission is not associated with VTE risk and/or in‐hospital mortality.

Understanding the Pathophysiology of Thrombotic APS through Animal Models

Antiphospholipid syndrome (APS) is a leading acquired cause of thrombotic events, with a notable tendency to promote thrombosis in vascular beds of all sizes, including both arterial and venous circuits. While pathogenic antiphospholipid antibodies circulate at relatively stable levels in blood, thrombosis tends to manifest as discrete and acute events, suggesting the requirement for a “second hit.” While this two-hit model is generally accepted, much remains to be learned about exactly how antiphospholipid antibodies predispose to thrombosis in vivo and exactly how this predisposition interacts with the second hit. To this end, investigators have turned to animal models. Numerous approaches for modeling APS in animals have been described to date, each with potential advantages and disadvantages. This review will attempt to describe the most common APS models employed so far while discussing some pros and cons of each. Mechanisms of thrombotic APS that have thus far been explored in animal models will also be briefly addressed.

Coronavirus disease 2019 (COVID-19) and autoimmunity

The coronavirus 2019 pandemic (coronavirus disease, COVID-19), etiologically related to the SARS-CoV-2 virus (severe acute respiratory syndrome coronavirus-2), has once again reawakened healthcare professionals’ interest towards new clinical and conceptual issues of human immunology and immunopathology. An unprecedented number of clinical trials and fundamental studies of epidemiology, virology, immunology and molecular biology, of the COVID-19 clinical course polymorphism and pharmacotherapy have been conducted within one year since the outbreak of 2019 pandemic, bringing together scientists of almost all biological and physicians of almost all medical specialties. Their joint efforts have resulted in elaboration of several types of vaccines against SARS-CoV-2 infection and, in general, fashioning of more rational approaches to patient management. Also important for COVID-19 management were all clinical trials of biologics and “targeted” anti-inflammatory drugs modulating intracellular cytokine signaling, which have been specifically developed for treatment immune-mediated inflammatory rheumatic disease (IMIRDs) over the past 20 years. It became obvious after a comprehensive analysis of the entire spectrum of clinical manifestations and immunopathological disorders in COVID-19 is accompanied by a wide range of extrapulmonary clinical and laboratory disorders, some of which are characteristic of IMIRDs and other autoimmune and auto-in-flammatory human diseases. All these phenomena substantiated the practice of anti-inflammatory drugs repurposing with off-label use of specific antirheumatic agents for treatment of COVID-19. This paper discusses potential use of glucocorticoids, biologics, JAK inhibitors, etc., blocking the effects of pro-inflammatory cytokines for treatment of COVID-19.

Thrombotic risk in antiphospholipidic syndrome: From hypothesis to current evidence (Review)

Thirty-five years after it was first described, antiphospholipid syndrome (APS) is unanimously recognized as a systemic autoimmune disease, a major acquired thrombophilia, which can affect any arterial or venous vascular territory, explaining the great diversity of clinical manifestations. The current classification criteria updated in the International Consensus Statement for Definite Antiphospholipid Syndrome from Sydney cannot explain alone the unpredictable evolution with thrombotic events of the patients diagnosed with APS. Although the link to genetics and epigenetics has not been clearly defined as in other autoimmune diseases, it is clear that a proper stratification of thrombotic risk in the era of personalized medicine must include classic biological markers (antiphospholipid antibodies, aPL), along with the already recognized phenotypes, non-conventional serological markers, and additional genetic risk factors for thrombosis. Moreover, with advancing age, a patient with APS develops other thrombotic risk factors which include: hypertension and dyslipidemia among others. According to the classification criteria, a patient is considered to have a low, moderate or high thrombotic risk. In clinical practice, patients with the same risk score may have completely different evolutions in terms of the recurrence of thrombosis. Concerning this approach, it appears that new non-conventional serological markers, phenotype-assessment and genetic determinants have an increasing importance and should be reconsidered in a proper thrombotic risk evaluation in patients with APS, compared to the initial concept of APS as first defined.

Testing for antiphospholipid antibodies: Advances and best practices

The diagnosis of antiphospholipid syndrome (APS) relies on the detection of circulating antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LAC), anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are included as laboratory criteria if persistently present. Progress has been made on the standardization of tests as guidelines on LAC testing and immunological assays for aCL and aβ2GPI are published. However, LAC measurement remains a complicated procedure with many pitfalls and interfered by anticoagulant therapy. Solid-phase assays for aCL and aβ2GPI still show interassay differences. These methodological issues make the laboratory diagnosis of APS challenging. In the interpretation of aPL results, antibody profiles help in identifying patients at risk. Noncriteria aPL, such as antibodies against the domain I of beta2-glycoprotein (aDI) and antiphosphatidylserine-prothrombin (aPS/PT) antibodies have been studied in the last years and may be useful in risk stratification of APS patients. But, aDI and aPS/PT are not included in the current diagnostic criteria and testing in daily practice is not recommended as these antibodies have no added value in the diagnosis of APS. This review will focus on the technical aspects of the laboratory methods, the clinical relevance of assays and interpretation of aPL results in the diagnosis of APS.

The Weight of IgA Anti-β2glycoprotein I in the Antiphospholipid Syndrome Pathogenesis: Closing the Gap of Seronegative Antiphospholipid Syndrome

The specific value of IgA Anti-β2glycoprotein I antibodies (aB2GP1) in the diagnosis and management of antiphospholipid syndrome (APS) is still controversial and a matter of active debate. The relevance of the IgA aB2GP1 isotype in the pathophysiology of APS has been increasingly studied in the last years. There is well know that subjects with multiple positive APS tests are at increased risk of thrombosis and/or miscarriage. However, these antibodies are not included in the 2006 APS classification criteria. Since 2010 the task force of the Galveston International Congress on APS recommends testing IgA aB2GP1 isotype in patients with APS clinical criteria in the absence of criteria antibodies. In this review, we summarize the molecular and clinical “state of the art” of the IgA aB2GP in the context of APS. We also discuss some of the characteristics that may help to evaluate the real value of the IgA aB2GP1 determination in basic research and clinical practice. The scientific community should be aware of the importance of clarifying the role of IgA aB2GP1 in the APS diagnosis.

Molecular Mechanisms of "Antiphospholipid Antibodies" and Their Paradoxical Role in the Pathogenesis of "Seronegative APS"

Antiphospholipid Syndrome (APS) is an autoimmune disease characterized by arterial and/or venous thrombosis and/or pregnancy morbidity, associated with circulating antiphospholipid antibodies (aPL). In some cases, patients with a clinical profile indicative of APS (thrombosis, recurrent miscarriages or fetal loss), who are persistently negative for conventional laboratory diagnostic criteria, are classified as "seronegative" APS patients (SN-APS). Several findings suggest that aPL, which target phospholipids and/or phospholipid binding proteins, mainly β-glycoprotein I (β-GPI), may contribute to thrombotic diathesis by interfering with hemostasis. Despite the strong association between aPL and thrombosis, the exact pathogenic mechanisms underlying thrombotic events and pregnancy morbidity in APS have not yet been fully elucidated and multiple mechanisms may be involved. Furthermore, in many SN-APS patients, it is possible to demonstrate the presence of unconventional aPL ("non-criteria" aPL) or to detect aPL with alternative laboratory methods. These findings allowed the scientists to study the pathogenic mechanism of SN-APS. This review is focused on the evidence showing that these antibodies may play a functional role in the signal transduction pathway(s) leading to thrombosis and pregnancy morbidity in SN-APS. A better comprehension of the molecular mechanisms triggered by aPL may drive development of potential therapeutic strategies in APS patients.

Non-criteria Antiphospholipid Antibodies: a narrative review

SUMMARY The 2006 Revised Sapporo Classification Criteria for Definite Antiphospholipid Syndrome included as laboratory criteria the tests for antiphospholipid antibodies whose accuracy was regarded as satisfactory according to the evidence available at that time. In practice, however, the sensitivity and specificity of these “criteria” of antiphospholipid antibodies are sometimes insufficient for identifying or ruling out antiphospholipid syndrome. It has been studied whether the accuracy of the laboratory diagnosis of the syndrome could be improved by testing for non-criteria antiphospholipid antibodies. In this work, we review evidence on the clinical associations and diagnostic value of the most commonly studied non-criteria antibodies, namely: antiphosphatidylethanolamine, anti-annexin A5, anti-prothrombin, anti-phosphatidylserine/prothrombin complex, IgA anticardiolipin, and IgG anti-domain I of the β2 glycoprotein antibodies.

Immunoglobulin A Isotype of Antiphospholipid Antibodies Does Not Provide Added Value for the Diagnosis of Antiphospholipid Syndrome in a Chinese Population

Objective

Antiphospholipid syndrome (APS) is characterized by the presence of anti-phospholipid (aPL) antibodies. However, the relationship between the immunoglobulin (Ig) A isotype of aPL positivity and its clinical utility in APS diagnosis is controversial. Presently, we determine the clinical utility of IgA-aPL from consecutive patients in a large cohort from the Chinese population and patients with APS whose aPL profiles were obtained.

Methods

The detection of anticardiolipin (aCL) and anti-β₂ glycoprotein-Ⅰ (aβ₂GPⅠ) antibodies of the IgA/IgG/IgM isotype by paramagnetic particle chemiluminescent immunoassay was carried out in sera from 7293 subjects. 153 primary APS (PAPS) patients and 59 patients with secondary APS (SAPS) were included in this study.

Results

In total, 1,082 out of 7,293 (2.55%) subjects had a positive IgA-aPL test, and the prevalence of isolated IgA-aPL was 0.29% (21/7,293) in the general population. The prevalence of IgA-aPL in the PAPS patients was 12.42% (19/153); however, only one patient (0.65%) presented with isolated IgA-aPL. Fifty (25.9%) of the SAPS had IgA-aPL, none of whom lacked IgG/IgM-aPL. The combination of the IgA isotype and the IgG/IgM isotype did not increase the diagnostic performance when compared with the IgG/IgM isotype of aCL or aβ₂GPⅠ, respectively. IgA-aPL was not associated with clinical manifestation in patients with APS.

Conclusion

Isolated IgA-aPL is rare in the general population as well as in patients with APS. Whether in the laboratory or in clinical practice, the presence of IgA-aPL does not provide added value for the diagnosis of APS in the Chinese population.

Antiphospholipid syndrome in pediatric patients

PURPOSE OF REVIEW

The purpose of this review is to summarize the diagnosis and management of the antiphospholipid syndrome (APS) in children.

RECENT FINDINGS

APS is a rare, acquired autoimmune systemic disease that can result in significant morbidity in children related to vascular thrombosis. The diagnosis and management of APS in children can be challenging due to a lack of validated diagnostic criteria and the rarity of the disease. In addition, many healthy children have transient circulating antiphospholipid antibodies without thrombotic complications. Nevertheless, epidemiological studies suggest that APS represents a greater relative proportion of thrombotic disease in children than it does in adults. Management of pediatric APS is largely inferred from adult data despite unique characteristics of pediatric APS. The current recommendations include long-term anticoagulation, which can be problematic in young, active individuals. There is little data on potential benefits of nonantithrombotic therapy in the management of pediatric APS.

SUMMARY

Data on pediatric APS are limited, but evidence suggests that using current available diagnostic testing is valuable and, until further evidence is available, treating thrombotic complications with heparins or warfarin should be standard of care.

Antiphospholipid antibodies in patients with COVID-19: A relevant observation?

BACKGROUND

High incidence of thrombosis in COVID-19 patients indicates a hypercoagulable state. Hence, exploring the involvement of antiphospholipid antibodies (aPL) in these patients is of interest.

OBJECTIVES

To illustrate the incidence of criteria (lupus anticoagulant [LAC], anticardiolipin [aCL] immunoglobulin G [IgG]/IgM, antibeta2-glycoprotein I antibodies [aβ2GPI] IgG/IgM) and noncriteria (anti-phosphatidyl serine/prothrombin [aPS/PT], aCL, and aβ2GPI IgA) aPL in a consecutive cohort of critically ill SARS-CoV-2 patients, their association with thrombosis, antibody profile and titers of aPL.

PATIENTS/METHODS

Thirty-one consecutive confirmed COVID-19 patients admitted to the intensive care unit were included. aPL were measured at one time point, with part of the aPL-positive patients retested after 1 month.

RESULTS

Sixteen patients were single LAC-positive, two triple-positive, one double-positive, one single aCL, and three aCL IgG and LAC positive. Seven of nine thrombotic patients had at least one aPL. Sixteen of 22 patients without thrombosis were aPL positive, amongst them two triple positives. Nine of 10 retested LAC-positive patients were negative on a second occasion, as well as the double-positive patient. Seven patients were aPS/PT-positive associated to LAC. Three patients were aCL and aβ2GPI IgA-positive.

CONCLUSION

Our observations support the frequent single LAC positivity during (acute phase) observed in COVID-19 infection; however, not clearly related to thrombotic complications. Triple aPL positivity and high aCL/aβ2GPI titers are rare. Repeat testing suggests aPL to be mostly transient. Further studies and international registration of aPL should improve understanding the role of aPL in thrombotic COVID-19 patients.

Comparative study of obstetric antiphospholipid syndrome (OAPS) and non-criteria obstetric APS (NC-OAPS): report of 1640 cases from the EUROAPS registry

OBJECTIVES

To compare clinical features, laboratory data and fetal-maternal outcomes between 1000 women with obstetric APS (OAPS) and 640 with aPL-related obstetric complications not fulfilling Sydney criteria (non-criteria OAPS, NC-OAPS).

METHODS

This was a retrospective and prospective multicentre study from the European Registry on Obstetric Antiphospholipid Syndrome.

RESULTS

A total of 1650 women with 5251 episodes, 3601 of which were historical and 1650 latest episodes, were included. Altogether, 1000 cases (OAPS group) fulfilled the Sydney classification criteria and 650 (NC-OAPS group) did not. Ten NC-OAPS cases were excluded for presenting thrombosis during follow-up. All cases were classified as category I (triple positivity or double positivity for aPL) or category II (simple positivity). Overall, aPL laboratory categories showed significant differences: 29.20% in OAPS vs 17.96% in NC-OAPS (P < 0.0001) for category I, and 70.8% in OAPS vs 82% in NC-OAPS (P < 0.0001) for category II. Significant differences were observed when current obstetric complications were compared (P < 0.001). However, major differences between groups were not observed in treatment rates, livebirths and thrombotic complications. In the NC-OAPS group, 176/640 (27.5%) did not fulfil Sydney clinical criteria (subgroup A), 175/640 (27.34%) had a low titre and/or non-persistent aPL positivity but did meet the clinical criteria (subgroup B) and 289/640 (45.15%) had a high aPL titre but did not fulfil Sydney clinical criteria (subgroup C).

CONCLUSION

Significant clinical and laboratory differences were found between groups. Fetal-maternal outcomes were similar in both groups when treated. These results suggest that we could improve our clinical practice with better understanding of NC-OAPS patients.

A woman with systemic lupus erythematosus, multiple pregnancy complications, and cerebral infarction who was only positive for phosphatidylserine-dependent antiprothrombin antibodies

A woman with systemic lupus erythematosus (SLE) had a history of two abortions before the 10th week, two foetal deaths with normal morphology, and one premature before the 34th week with early-onset hypertensive disorder of pregnancy (HDP) and placental dysfunction. Although she did not have any conventional antiphospholipid antibodies (aPLs), antiphospholipid syndrome (APS) was strongly suspected based on her obstetric history and renal biopsy findings consistent with aPL-associated nephropathy (APLN). Eventually, she was found to be positive for phosphatidylserine-dependent antiprothrombin antibodies (aPS/PTs). A healthy baby was born with anticoagulation and intravenous immunoglobulin (IVIG) therapy during pregnancy. aPS/PT titres gradually increased after delivery. Cerebral infarction occurred at 9 years after birth. If APS is clinically suspected but the antibodies included in the classification criteria for APS are all negative, we should consider an association with unconventional aPLs and manage according to APS.