Pediatric antiphospholipid syndrome: expanding our understanding of antiphospholipid syndrome in children

PURPOSE OF REVIEW

Antiphospholipid syndrome (APS) is an autoimmune, thromboinflammatory disease, which affects children and adults. There are particular features of the disease and nuances to diagnosis and management in a pediatric population, which must be appreciated to improve clinical care.

RECENT FINDINGS

Pediatric-specific epidemiological studies highlight that pediatric APS is quite rare with incidence in some populations of 0.2 per 100 000. There are new classification criteria in APS, which include a wider range of clinical features increasingly identified in registry data and case series of pediatric APS, though validation in pediatric APS is still needed. There is a particularly high proportion of pediatric APS patients with noncriteria antiphospholipid antibodies (aPL). Recurrent thrombosis is especially common in pediatric APS, highlighting the difficulty of management of this disease with high morbidity in children.

SUMMARY

Recent research has enhanced understanding of pediatric-specific APS epidemiology, laboratory findings, the wide variety of clinical features, and challenges in successful treatment. Future directions could include evaluation of potentially unique features in pediatric pathophysiology, an evaluation of the new APS classification criteria in children, broader prospective data on clinical and laboratory features, and a continued search for treatment beyond committing young patients to lifelong anticoagulation.

An update on laboratory detection and interpretation of antiphospholipid antibodies for diagnosis of antiphospholipid syndrome: guidance from the ISTH-SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies

Antiphospholipid syndrome (APS) diagnosis is dependent on the accurate detection and interpretation of antiphospholipid antibodies (aPL). Lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and anti-beta2 glycoprotein I antibodies (aβ2GPI) remain the cornerstone of the laboratory part of APS diagnosis. In the 2023 American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) APS classification criteria, the type of laboratory parameters remain essentially unchanged compared with the updated Sapporo classification criteria, and aCL and aβ2GPI measurement are still restricted to enzyme-linked immunosorbent assays (ELISAs) with moderate and high titer aPL thresholds defined as 40 and 80 Units, respectively, and a cutoff calculated by the 99th percentile has been abandoned. We must differentiate between classification criteria and assessment of aPL in clinical care. Classification criteria are strict and meant for participant inclusion in studies and trials to study homogeneous populations of patients. In contrast, laboratory detection for APS diagnosis in daily practice is broader, meant to diagnose each APS patient to optimize their management. Nowadays, there is increasing use of measurement of aPL by methods other than ELISAs , the semiquantitative reporting of titers is a matter of debate, as well as the role of the isotypes immunoglobulin (Ig)M and IgA, and the role of other aPL, such as antiphosphatidylserine (aPS)/prothrombin (PT) antibodies. Patients diagnosed with the disease may or may not fulfill the classification criteria, and inappropriate use of classification criteria may lead to mis(under)diagnosis. The aim of this guidance, based on literature and expert opinion, is to provide guidance recommendations for laboratory workers and clinicians on routine diagnostic assessment of patients with suspected APS.

Association of Anti-Annexin A5 Antibody With Pregnancy Outcomes: A Cohort Study: Anti-annexin A5 antibody with pregnancy outcomes

OBJECTIVE

This study aims to evaluate the correlation between anti-annexin A5 (aANXA5) antibody in the blood and pregnancy outcomes .

METHODS

This study is a retrospective cohort study based on singleton pregnancies of the Third Affiliated Hospital of Wenzhou Medical University from May 2018 to December 2022. Baseline characteristics were collected from all participants. Logistic regression and interaction effect analyses were utilized to examine the risk impact of aANXA5 on pregnancy complications, adjusting for age, BMI, abortion, ANA, and aCL. Restricted cubic spline (RCS) and threshold effect analysis were applied to explore the relationship between aANXA5 levels and preterm birth (PTB), as well as pregnancy-induced hypertension (PIH).

RESULTS

The study included 501 participants, with 51 (10.2%) testing positive for aANXA5 and 450 (89.8%) testing negative. The aANXA5 positive group exhibited higher rates of ANA and antibodies to thyroglobulin (TGAb), along with increased incidences of PTB and PIH. Positive aANXA5 status was independently linked to an elevated risk of PTB (OR: 2.53, 95% CI: 1.30-4.94) and PIH (OR: 4.23, 95% CI: 1.54-11.62). Subsequent subgroup analysis indicated no significant interaction between the groups (p > 0.05). Threshold analysis revealed that the OR for PTB was 1.20 (95% CI: 1.03-1.39) in participants with aANXA5 levels ≥ 32.77 ng/mL, and the OR for PIH was 1.62 (95% CI: 1.15-2.28) in those with aANXA5 levels ≥ 33.20 ng/mL.

CONCLUSION

AANXA5 is independently associated with an increased risk of PTB and PIH. The identified optimal predictive cutoff values are 32.77 ng/mL for PTB and 33.20 ng/mL for PIH.

Preconception Non-criteria Antiphospholipid Antibodies and Risk of Subsequent Early Pregnancy Loss: a Retrospective Study

The aim of this study was to investigate the subsequent early pregnancy outcomes in women positive for non-criteria antiphospholipid antibodies (NC-aPLs) before pregnancy. A total of 273 patients who had experienced sporadic or recurrent pregnancy loss and had been screened for 13 NC-aPLs at preconception were recruited in this study from September 2019 to February 2022. Serum levels of NC-aPLs were measured by ELISA using specific kits. The primary outcome was early pregnancy loss, and the secondary outcomes were biochemical pregnancy, clinically confirmed pregnancy loss, and ongoing pregnancy. Among these subjects, 56 patients had one previous pregnancy loss, and 217 had recurrent pregnancy loss (RPL). The NC-aPLs (+) and NC-aPLs (-) groups had similar rates of early pregnancy loss (EPL) after adjustment, regardless of the number of positive NC-aPLs (aOR = 1.054, 95% CI 0.602-1.846). Other outcomes were comparable in both groups, including the rates of biochemical pregnancy (aOR = 1.344, 95% CI 0.427-4.236), clinically confirmed pregnancy loss (aOR = 0.744, 95% CI 0.236-2.344), and ongoing pregnancy (aOR = 0.949, 95% CI 0.542-1.660). Based on sensitivity analysis, the NC-aPLs (+) were not associated with adverse early pregnancy outcomes in women with RPL. Furthermore, the difference in gestational weeks of pregnancy loss between the two groups was also insignificant. This study found no evidence linking preconception NC-aPL positivity to early pregnancy outcomes but offers a reference for future research to clarify NC-aPLs' potential clinical impact.

Viewpoint: The value of non-criteria antiphospholipid antibodies

In 2006, at a meeting in Sydney, Australia, consensus was reached by an international group of specialists to establish a number of serological criteria that identify patients with a history of thrombosis or pregnancy complications as having antiphospholipid syndrome (APS). These criteria were originally formulated for research purposes and to compare clinical trials in different centres. However, these same criteria are now generally used and accepted for the diagnosis and treatment of patients. The practice of using these criteria for direct patient care requires that these criteria are based on sound scientific evidence. Indeed, for all the autoantibodies that are officially included in the serological criteria, it has been shown that they induce thrombosis and fetal loss when infused into mice. There are also a number of additional autoantibodies that have been identified in these patients but for these antibodies there was not enough evidence to meet the official APS criteria in 2006. Seventeen years have now passed since the consensus meeting, therefore, this review examines whether additional studies performed with these 'non-criteria' autoantibodies have provided sufficient results to suggest the inclusion of these autoantibodies in the official serological criteria of APS.

Thrombin generation assay and lupus anticoagulant synergically distinguish populations of patients with antiphospholipid antibodies

AIM

To apply thrombin generation assay (TGA) in a large cohort of antiphospholipid antibodies (aPL)-positive patients.

MATERIAL AND METHODS

108 patients were tested with TGA and lupus anticoagulant (LA) testing and divided according to their aPL profile. Briefly, 21 patients were positive for anti-phosphatidylserine (aPS)/prothrombin (PT) IgG/IgM (group1), 29 for anti-ß2-glycoprotein-I (aβ2GPI) and anti-cardiolipin (aCL) IgG/IgM (group2), 31 for aPS/PT, aβ2GPI and aCL IgG/IgM (group3), 27 for aPS/PT and/or aβ2GPI+aCL IgM at low-titres (group4). 31 healthy donors (HDs) and 24 controls treated with vitamin K antagonists (VKA) were included.

RESULTS

The most deranged TGA and LA profiles were observed in tetra-positive patients (group3) that differed significantly to the other groups, thus those with isolated, double or triple aPL-positivity. Moreover, when comparing the TGA profile of all antiphospholipid syndrome (APS) patients, aPL-carriers, HDs and VKA controls, we observed that the aPL+ patients (especially APS) showed a distinctive profile that allowed to distinguish them from the other groups with significantly higher tLag and tPeak, and lower Peak and area under the curve.When focusing on APS clinical manifestations, patients with a high-risk profile (group3) showed significant differences from those presenting low-titres aPL (group 4) regarding the number of venous events (p=0.04), recurrence of any thrombotic event (p=0.01), of arterial events (5 vs 0, p=0.02), the occurrence of TIA (p=0.04), DVT (p=0.02) and, when analysing extracriteria manifestations, of peripheral artery disease (p=0.04).

CONCLUSIONS

TGA seems a valuable approach to stratify aPL+ patients according to their risk profile. The differences among different populations of autoantibodies specificities could be considered a translational validation of the increased thrombotic risk of patients with triple or tetra aPL-positivity.

16th International congress on antiphospholipid antibodies task force report on antiphospholipid syndrome laboratory diagnostics and trends

Classification criteria for antiphospholipid syndrome (APS) require IgG or IgM isotypes of the anticardiolipin (aCL) antibodies, anti-β2 glycoprotein I (anti-β2GPI) antibodies, and/or the lupus anticoagulant (LA) to satisfy the laboratory disease definition. Over the past 20 years, non-criteria antiphospholipid antibodies (aPL) directed to other proteins of the coagulation cascade (i.e. prothrombin and/or phosphatidylserine-prothrombin complex) or to some domains of β2GPI have been proposed. This task force concentrated and reviewed the literature on data including aPS/PT, antibodies to domain 4/5 of β2GPI and the newly described antibodies to protein/HLA-DR complex. In addition, we discussed testing of LA in the 'new' oral anticoagulants' era and the value of triple positivity in the risk assessment of aPL. The conclusions were presented at a special session during the 16th International Congress on aPL, Manchester, UK, September 2019.

Antibodies to Domain I β2-Glycoprotein 1 in Patients with Antiphospholipid Syndrome and Systemic Lupus Erythematosus

The role of antiphospholipid antibodies (aPL), which are not included in the Sydney diagnostic criteria, in antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) is poorly understood. The aim of this study was to determine the clinical significance of IgG antibodies for domain 1 of β2-glycoprotein 1 (β2-GP1), IgG anti-β2-GP1DI, in patients with APS with and without SLE. The study included 187 patients with APS with or without SLE, 49 patients formed the comparison group, and 100 apparently healthy individuals formed the control group. IgG/IgM antibodies to cardiolipin (aCL) and IgG/IgM anti-β2-GP1 were determined by enzyme immunoassay (ELISA) in patients with or without APS, and IgG anti-β2-GP1DI was determined by chemiluminescence assay (CLA) in all patients and controls. IgG anti-β2-GP1DI was detected in 37 (71%) of 52 patients with primary APS (PAPS), in 6 (50%) of 12 patients with probable APS, in 42 (71%) of 59 patients with SLE + APS, in 17 (26%) of 64 patients with SLE, in 1 (2%) of the comparison group, and in none of the control group. IgG anti-β2-GP1DI was significantly associated with PAPS and SLE + APS compared with the patients with SLE (p = 0.0002 and 0.0001, respectively). The association of IgG anti-β2-GP1DI with clinical manifestations of APS (thrombosis (p = 0.001) and obstetric pathology (p = 0.04)) was detected. There was a significant association of IgG anti-β2-GP1DI with arterial thrombosis (p = 0.002) and with late gestational obstetric pathology (p = 0.01). High specificity of IgG anti-β2-GP1DI depending on the diagnosis and clinical manifestations of APS despite low sensitivity was noted: specificity was 84% for thrombosis, 94% for obstetric pathology, and 89% for APS. Isolated IgG anti-β2-GP1DI positivity was reported in 2% of 50 aPL-negative patients and was not associated with APS manifestations. The frequency of IgG anti-β2-GP1DI detection was higher in the patients with APS compared to the patients with SLE, comparison group, and control (p < 0.05). Positive IgG anti-β2-GP1DI values were significantly associated with thrombotic complications and with obstetric pathology (p = 0.002 and p = 0.01, respectively). Specificity of IgG anti-β2-GP1DI for APS and its clinical manifestations (thrombosis and obstetric pathology) was higher than sensitivity (89, 94, and 84%, respectively).

Non-Criteria Obstetric Antiphospholipid Syndrome: How Different Is from Sidney Criteria? A Single-Center Study

This study aims to compare the demographic characteristics, clinical features, serology, and fetal-maternal outcomes between women with obstetric antiphospholipid syndrome (APS) and those with non-criteria (NC)-APS and seronegative (SN)-APS. Two-hundred and sixty-three women with APS obstetric morbidity ever pregnant were included. Of those, 66 met the APS classification criteria, 140 were NC-APS, and 57 were SN-APS. Patients with other autoimmune diseases were excluded. Adverse pregnancy outcomes (APO) included early pregnancy loss, fetal death, preeclampsia, abruptio placentae, and preterm birth. The mean age of the study group was 33.6 ± 5.3 years, and patients were followed up for 129.5 ± 81.9 months. In the NC-APS group, 31 (22.1%) did not fulfill clinical and serological criteria (Subgroup A), 49 (35%) did meet clinical but not serologic criteria (Subgroup B), and 60 (42.9%) fulfilled the serologic criteria but not the clinical ones (Subgroup C). The cardiovascular risk burden was higher in the APS group, due to a higher proportion of smoking. Patients with criteria APS received more intensive treatment than patients in the other study groups. The addition of standard of care (SoC) treatment significantly improved live birth and decreased APO in all groups. Significant clinical differences were observed between the study groups. However, when treated with SoC, fetal-maternal outcomes were similar, with a significant improvement in live births and a decrease in APO. Risk stratification in patients with obstetric morbidity associated with APS can help individualize their treatment.

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.

Non-criteria antiphospholipid antibodies and pediatric rheumatic disease: a case series

BACKGROUND

Non-criteria antiphospholipid antibodies (NC-aPL) are a relatively undefined subgroup of antiphospholipid antibodies (aPL). Knowledge about NC-aPL in adults is limited and even less is known in pediatric patients. Routine tests for antiphospholipid syndrome (APS)-a clinical state marked by the presence of aPL in association with vascular thrombosis-usually include lupus anticoagulant (LAC), anti-cardiolipin (aCL) and -beta-2 glycoprotein I (aβ2GPI). LAC is a functional screen for prothrombotic aPL, while the latter tests identify specific autoantibodies. Specific targets of NC-aPL include, but are not limited to, phosphatidylethanolamine, phosphatidylserine, and prothrombin.

PRESENTATION OF CASES

We present single-center data from eight pediatric patients with NC-aPL identified during a three-year period. All patients had presenting features raising suspicion for APS. Most patients were female with a primary rheumatic disease. One patient had a stroke. Another patient had alveolar hemorrhage and pulmonary hypertension. Raynaud's phenomenon, rashes involving distal extremities, and headaches were common. Most patients had a positive LAC, yet their routine aPL tests were negative, prompting testing for NC-aPL.

CONCLUSIONS

Our findings suggest NC-aPL are associated with typical signs and symptoms of APS in pediatric patients. Pediatricians and pediatric subspecialists should consider NC-aPL when clinical suspicion is high and routine aPL tests are negative, particularly when LAC is positive. While guidelines for NC-aPL do not yet exist for children or adults, these autoantibodies have pathogenic potential. Actionable items could include evaluation for the presence of other (primary) rheumatic diseases, and consultation with hematologists and/or obstetricians regarding anticoagulation/platelet inhibition and thrombosis education. Future guidelines regarding NC-aPL will only be generated by gathering more data, ideally prospectively.

Research progress on ANXA5 in recurrent pregnancy loss

The incidence of recurrent pregnancy loss (RPL) in fertile women ranges from 1% to 5%, of which about 50% of them are due to unknown causes. The possible pathogenesis of RPL is an urgent problem to be solved in the clinical. Mutations or polymorphisms of certain genes in the coagulation mechanism are associated with susceptibility to thrombotic diseases and are one of the main reasons for the occurrence of RPL. Among them, the ANXA5 gene was newly studied and some single nucleotide polymorphisms (SNPs) in the promoter region of ANXA5 have been reported to be associated with RPL in multiple races. In this review, we summarized the research progress on the correlation between the SNPs in ANXA5 and RPL, hoping to provide some valuable guidance for the future studies.

Frequency of serological markers of rheumatoid arthritis in patients with IgA anti-β2 glycoprotein I antibodies

Aim

To determine the frequency of serological markers of RA in patients with anti‐β2 glycoprotein I antibodies (aβ2GPI) of IgA isotype.

Material and Methods

A retrospective study was conducted on 67 patients with aβ2GPI‐IgA. Ninety healthy blood donors (HBD) were used as a control group. IgG anti‐cyclic citrullinated peptides antibodies (CCP‐Ab) and rheumatoid factors (RF) IgG, IgA, and IgM were detected by enzyme‐linked immunosorbent assay (ELISA).

Results

Seventeen patients and eight HBD had CCP‐Ab and/or RF (25.4% vs. 8.9%, p = 0.005, CI 95% [14.95; 35.79], odds ratio = 3.5). The frequency of CCP‐Ab was significantly higher in patients than in healthy subjects (14.9% vs. 3.3%, p = 0.009). IgA isotype of RF was significantly higher in patients than in controls (7.5% vs. 0%, p = 0.02). In male patients, CCP‐Ab and/or RF were more frequent than in healthy male subjects (37.5% vs. 11.8%, p = 0.02). In patients, no correlation was found between the levels of aβ2GPI‐IgA and CCP‐Ab (r = 0.082, p = 0.51). There was no correlation between the level aβ2GPI‐IgA and the level of the isotypes of RF (IgG, IgA, and IgM) in patients (r = 0.1, p = 0.37; r = 0.17, p = 0.17 and r = 0.07, p = 0.59 respectively).

Conclusion

Frequencies of CCP‐Ab and RF are high in patients with aβ2GPI‐IgA suggesting that these patients are susceptible to developing RA.

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.

Cerebrovascular events in patients with isolated anti-phosphatidyl-serine/prothrombin antibodies

The interest of extra-criteria antiphospholipid antibodies is growing, especially in patients negative for conventional antibodies. In this study we aimed to assess the clinical utility of anti-phosphatidyl-serine/prothrombin antibodies (aPS/PT) testing in patients negative for Beta2-Glycoprotein 1(β2GPI)-dependent tests, for identifying antiphospholipid syndrome (APS) patients that developed cerebrovascular events (CVE). When screening APS patients attending our center, out of 119 aPS/PT IgG/IgM-positive patients, thus patients negative for aβ2GPI and aCL, 42 patients (35%) tested negative for β2GPI-dependent tests and were tested with thrombin generation assay (TGA). Ten patients (24%), with isolated aPS/PT IgG/IgM, had a history of CVE. Lupus anticoagulant (LA)-positive test was more frequently observed in patients with CVE (8/22 vs. 2/20; p = 0.045). Out of the 10 patients who experienced CVE, 3 patients were aPS/PT IgG positive (all LA positive), and 8 patients were aPS/PT IgM positive (6/8 LA positive). One patient was positive for both aPS/PT IgG and IgM. LA-positive patients had only high titers of aPS/PT IgG/IgM, all of them being ≥ 80 U/ml, while the 2 LA-negative patients were aPS/PT IgM positive with medium titers [40-60 U/ml]. LA-positive patients had significantly altered TGA profile when compared to those who were LA negative, considering all TGA parameters. LA-positive patients had significantly higher tLag (8.4 ± 3.3 min vs. 6.6 ± 1.8 min; p = 0.046), higher tPeak (14 ± 4.3 min vs. 11 ± 2.7 min; p = 0.015) and lower Peak (207 ± 152 nM vs. 356.3 ± 104.7 nM; p < 0.001) and lower AUC (2109.7 ± 1006.9 nM vs. 2772.5 ± 776.8 nM; p = 0.033). The use of aPS/PT might be of help in identifying patients with CVE and APS, as also confirmed by TGA testing.

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.

Clinical manifestations in patients with antiphospholipid antibodies: Beyond thrombosis and pregnancy loss

The clinical spectrum of the antiphospholipid syndrome (APS) encompasses additional manifestations other than thrombosis and pregnancy morbidity, which may potentially affect every organ and system. The pathophysiology of APS indeed cannot be explained exclusively by a prothrombotic state and the "extra-criteria" manifestations of the syndrome should be attributed to other mechanisms, such as inflammation, complement and platelet activation. In this case-series, we report patients with uncommon clinical APS presentations, to highlight relevant peculiarities of the syndrome, potentially paving the way for a further update of clinical as well as laboratory manifestations of this complex immunological condition.

Low prevalence of antiannexin A5 antibodies in unprovoked venous thrombosis

INTRODUCTION

The antiphospholipid syndrome (APS) is characterized by thrombosis or pregnancy morbidity, and the detection in the blood of at least one of three antiphospholipid antibodies (lupus anticoagulant, or anticardiolipin or anti-β₂ -glycoprotein I antibodies). Diagnosing APS is important so that secondary prophylaxis may be administered to reduce risk of recurrent thrombosis and/or pregnancy morbidity. In addition to APS-defining antibodies, there may be additional autoantibodies that have a role in thrombosis and/or pregnancy morbidity. Furthermore, some patients have clinical manifestations highly suggestive of APS but are persistently negative for the APS-defining antibodies ("seronegative APS") and instead, have other autoantibodies. Antiannexin A5 (aANXA5) autoantibodies have been associated with increased risk of thrombosis and pregnancy morbidity; levels are also reportedly higher in patients with venous thrombosis compared with healthy controls. The prevalence of aANXA5 among patients with unprovoked venous thrombosis is not well-documented and determination of the frequency of aANXA5 is the objective of this study.

METHODS

We analysed sera from 148 patients with unprovoked venous thrombosis who had undergone routine laboratory testing for the present APS-defining antibodies.

RESULTS

aANXA5 IgG and IgM were present in 6% and 1%, respectively.

CONCLUSION

Prevalence of these antibodies in unprovoked venous thrombosis is comparable with frequencies reported in healthy individuals and is far lower than the prevalence in women with pregnancy morbidity. This may indicate lack of association with venous thrombosis, however, adequately powered case-control studies will be required to resolve this and prevalence data from this study will assist in the design of such studies.

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.

Avidity of anti-phospholipid antibodies in relation to their levels

Introduction

The heterogeneity of anti-phospholipid antibodies can be manifested not only in different antigenic specificities, but also in their avidities. The aim of the study was to investigate the relationship between anti-cardiolipin antibody (aCL) IgG avidities and levels within the range of their titres, from very low to high ones.

Material and methods

We analyzed 78 serum samples from 60 patients by ELISA with chaotropic agents, using urea concentration of 6 and 8 mol/l and single diluted serum samples. The changes of aCL levels and avidities were explored during a long-term follow-up in 14 patients.

Results

The avidities of aCLs did not differ in the groups of patients classified according to aCL levels. The higher avidity antibodies predominated in our patients and the fluctuation of avidities in the longitudinal follow-up did not show significant differences. No relationship between aCL levels and their avidities was found.

Conclusions

aCL avidities seem to have no relationship with aCL levels and high-avidity aCLs; the potentially deleterious effects might be present also in patients with low and extremely low aCL levels. Avidity of aCLs belongs to stable characteristics with insignificant changes in time.

Validation of the Particle-Based Multi-Analyte Technology for Detection of Anti-PhosphatidylSerine/Prothrombin Antibodies

Among “extra-criteria” antiphospholipid (aPL) antibodies, anti-phosphatidylserine/prothrombin (aPS/PT) antibodies, are considered a part of risk assessment strategies when investigating patients suspected of having antiphospholipid syndrome (APS). aPL detection is currently performed by solid-phase assays to identify anti-cardiolipin (aCL), anti-β2glycoprotein I (aβ2GPI) and aPS/PT antibodies, but new techniques are emerging. Among these, particle-based multi-analyte technology (PMAT), which allows the full automation and simultaneous digital detection of autoantibodies and proteins, including IgG, IgA and IgM isotypes of aCL, aβ2GPI and aPS/PT. The aim of this study was to investigate the agreement of aPS/PT testing between enzyme-linked immunosorbent assay (ELISA) and the PMAT platform. A total of 94 patients were enrolled in the study, including 71 patients with confirmed APS and 23 “aPL carriers”. aPS/PT IgG showed a moderate binomial agreement between ELISA and PMAT (k = 0.57, 95% CI 0.45–0.75), and aPS/PT IgM showed a moderate agreement (k = 0.60, 95% CI 0.45–0.75). Moreover, when considering the continuous agreement, both aPS/PT IgG and IgM showed a statistically significant correlation between ELISA and PMAT (Spearman’s correlation = 0.69, p < 0.001 and 0.72, p < 0.001, respectively). This study demonstrates that PMAT technology is a reliable method for aPS/PT IgG and IgM testing when compared to the available commercial ELISA kit.

Genetic Factors in Antiphospholipid Syndrome: Preliminary Experience with Whole Exome Sequencing

As in many autoimmune diseases, the pathogenesis of the antiphospholipid syndrome (APS) is the result of a complex interplay between predisposing genes and triggering environmental factors, leading to a loss of self-tolerance and immune-mediated tissue damage. While the first genetic studies in APS focused primarily on the human leukocytes antigen system (HLA) region, more recent data highlighted the role of other genes in APS susceptibility, including those involved in the immune response and in the hemostatic process. In order to join this intriguing debate, we analyzed the single-nucleotide polymorphisms (SNPs) derived from the whole exome sequencing (WES) of two siblings affected by APS and compared our findings with the available literature. We identified genes encoding proteins involved in the hemostatic process, the immune response, and the phospholipid metabolism (PLA2G6, HSPG2, BCL3, ZFAT, ATP2B2, CRTC3, and ADCY3) of potential interest when debating the pathogenesis of the syndrome. The study of the selected SNPs in a larger cohort of APS patients and the integration of WES results with the network-based approaches will help decipher the genetic risk factors involved in the diverse clinical features of APS.

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.

The prevalence of antiphospholipid antibodies in women with late pregnancy complications and low-risk for chromosomal abnormalities

BACKGROUND

Antiphospholipid antibodies (aPL) are known to increase the risk of obstetrical complications. However, aPL significance and prevalence in women with late-onset pregnancy complications (LO-PC) need further clarification.

OBJECTIVES

To investigate the prevalence of aPL in a cohort of women who experienced LO-PC and to compare it with a cohort of uneventful pregnancies.

METHODS

One hundred pregnant women who experienced LO-PC, had a low risk for chromosomal abnormalities, and absence of fetal abnormalities were recruited from August 2018 to August 2019. One hundred women with uneventful pregnancy were included as controls. aPL testing was performed on serum samples derived from prenatal screening test and included both criteria and "extra criteria" aPL.

RESULTS

Patients with LO-PC had significantly higher aPL prevalence when compared with controls (31/100 [31%] vs 10/100 [10%]; P < .001). More in detail, up to 26% of women with LO-PC were positive for one aPL, with an overall prevalence significantly higher than controls (26% vs 9%; P < .05). Among single aPL positivity, patients had significantly higher rate of positivity and titers of anticardiolipin IgG (10% vs 2%; mean ± standard deviation 11 ± 13 vs 4 ± 9.6 chemoluminescent unit; P < .05) and phosphatidylserine-prothrombin antibodies (aPS/PT) IgM (15% vs 6%; mean ± standard deviation 10.2 ± 21.7 vs 3.7 ± 13.7 U; P < .05). Testing for aPS/PT (IgM/IgG) alone allowed the identification of 17 patients negative for criteria aPL. aPL-positive patients had a significantly higher risk of preterm birth (34-36 + 6 weeks; 10% vs 8%; P < .012).

CONCLUSIONS

We report a high prevalence of aPL in our cohort. Testing for both criteria and "extra criteria" aPL in women with previous LO-PC could improve the diagnostic accuracy identifying women at higher risk for recurrent pregnancy complications.

Evaluation of novel assays for the detection of autoantibodies in antiphospholipid syndrome

Patients with antiphospholipid syndrome (APS) present with clinical features of recurrent thrombosis and pregnancy morbidity and persistently test positive for the presence of antiphospholipid antibodies (aPL). At least one clinical (vascular thrombosis or pregnancy morbidity) and one lab-based (positive test result for lupus anticoagulant, anticardiolipin antibodies and/or anti-β2-glycoprotein 1 antibodies) criterion have to be met for a patient to be classified as having APS. Nevertheless, the clinical variety of APS encompasses additional signs and symptoms, potentially affecting any organ, that cannot be explained exclusively by a prothrombotic state. Those manifestations, also known as extra-criteria manifestations, include haematologic (thrombocytopenia and haemolytic anaemia), neurologic (chorea, myelitis and migraine) manifestations as well as the presence of livedo reticularis, nephropathy and valvular heart disease. The growing body of evidence describing the clinical aspect of the syndrome has been paralleled over the years by emerging research interest focusing on the development of novel biomarkers that might improve the diagnostic accuracy for APS when compared to the current aPL tests. This review will focus on the clinical utility of extra-criteria aPL specificities. Besides, the promising role of a new technology using particle based multi-analyte testing that supports aPL panel algorithm testing will be discussed. Diagnostic approaches to difficult cases, including real-world case studies investigating the diagnostic added value of extra criteria aPL, particularly anti-phosphatidylserine/prothrombin, will also be examined.

Discovery and characterization of 2 novel subpopulations of aPS/PT antibodies in patients at high risk of thrombosis

Anti-phosphatidylserine/prothrombin (aPS/PT) antibodies are often detected in patients with antiphospholipid syndrome (APS), but how aPS/PT engage prothrombin at the molecular level remains unknown. Here, the antigenic determinants of immunoglobulin G aPS/PT were investigated in 24 triple-positive APS patients at high risk of thrombosis by using prothrombin mutants biochemically trapped in closed and open conformations, and relevant fragments spanning the entire length of prothrombin. Two novel unexpected findings emerged from these studies. First, we discovered that some aPS/PT are unique among other anti-prothrombin antibodies insofar as they efficiently recognize prothrombin in solution after a conformational change requiring exposure of fragment-1 to the solvent. Second, we identified and characterized 2 previously unknown subpopulations of aPS/PT, namely type I and type II, which engage fragment-1 of prothrombin at different epitopes and with different mechanisms. Type I target a discontinuous density-dependent epitope, whereas type II engage the C-terminal portion of the Gla-domain, which remains available for binding even when prothrombin is bound to the phospholipids. Based on these findings, APS patients positive for aPS/PT were classified into 2 groups, group A and group B, according to their autoantibody profile. Group A contains mostly type I antibodies whereas group B contains both type I and type II antibodies. In conclusion, this study offers a first encouraging step toward unveiling the heterogeneity of anti-prothrombin antibodies in correlation with thrombosis, shedding new light on the mechanisms of antigen-autoantibody recognition in APS.

[Seronegative antiphospholipid syndrome: Myth or reality?]

The antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombosis and/or obstetrical manifestations and the persistent presence, at least 12 weeks apart, of antiphospholipid antibodies (aPL) such as lupus anticoagulant (LA) and/or anticardiolipin antibodies (ACL) and/or anti-β2 glycoprotein I antibodies (aβ2GPI). The finding of patients with clinical profile highly suggestive of APS but who are negative for conventional biological criteria has led to the concept of seronegative APS. In the last few years, new antigen targets and methodological approaches have been employed to more clearly identify this syndrome in patients with thrombosis or obstetrical complications without conventional aPL. Although seronegative APS is still controversial, there is increasing recognition of the existence of this subgroup. However, clinical relevance of non conventional aPL need to be confirmed by efforts toward standardizing new biological tools and longitudinal studies involving large cohort of patients.

Anti-β2GPI domain 1 antibodies stratify high risk of thrombosis and late pregnancy morbidity in a large cohort of Chinese patients with antiphospholipid syndrome

INTRODUCTION

Anti-β2GPI-Domain 1 (β2GPI-D1) antibodies are considered to be a pathogenic subset of anti-β2GPI antibodies and have been strongly associated with thrombosis and pregnancy morbidity in patients with antiphospholipid syndrome (APS). We evaluated the clinical utility of anti-β2GPI-D1 IgG antibodies for stratifying the risk of thrombosis and/or pregnancy morbidity (PM) in a cohort of Chinese patients with APS and also assessed its correlation with the Global Anti-Phospholipid Syndrome Score (GAPSS).

MATERIALS AND METHODS

Sera and plasma from 192 consecutive APS patients, 17 aPL carriers, 193 patients with other systemic autoimmune diseases, and 120 healthy controls were collected and the presence of aCL IgG/IgM, anti-β2GPI IgG/IgM and anti-β2GPI-D1 IgG antibodies were assessed by chemiluminescence assays (CIA). Detection of LAC was performed according to international guidelines with the use of screening, mixing and confirmation tests. Anti-phosphatidylserine-prothrombin (aPS/PT) IgG and IgM antibodies were detected by commercial ELISA kits.

RESULTS

Anti-β2GPI-D1 IgG antibodies showed high specificity (97.12%) and moderate sensitivity (64.32%) for the diagnosis of APS. Anti-β2GPI-D1 antibodies levels were significantly higher in patients with triple aPL positivity than in those with double (P < 0.001) and single positive aPL (P < 0.001) and correlated well with the GAPSS (rho = 0.60, P < 0.001). Anti-β2GPI-D1 antibodies presented with a higher prevalence and higher titers in patients with late pregnancy morbidity (≥10 weeks) and thrombotic APS compared to those with early pregnancy (<10 weeks) morbidity. Higher anti-β2GP1-D1 antibodies titers effectively distinguished APS from other autoimmune diseases.

CONCLUSION

This study suggests a predictive role of anti-β2GPI-D1 IgG antibodies as a strong risk factor for both thrombotic and obstetric APS (OAPS), especially for stratification comparing early PM with late PM and thrombosis.

Evaluation of the sensitivity and specificity of a novel line immunoassay for the detection of criteria and non-criteria antiphospholipid antibodies in comparison to established ELISAs

Background

Persistent antiphospholipid antibodies (aPL) constitute the serological hallmark of the antiphospholipid syndrome (APS). Recently, various new assay technologies for the detection of aPL better suited to multiplex reaction environments than ELISAs emerged. We evaluated the diagnostic performance of such a novel line immunoassay (LIA) for the simultaneous detection of 10 different aPL.

Methods

Fifty-three APS patients and 34 healthy controls were investigated for criteria (antibodies against cardiolipin [aCL], β2-glycoprotein I [aβ2-GPI]) and non-criteria aPL (antibodies against phosphatidic acid [aPA], phosphatidyl-choline [aPC], -ethanolamine [aPE], -glycerol [aPG], -inositol [aPI], -serine [aPS], annexin V [aAnnV], prothrombin [aPT]) IgG and IgM by LIA. Criteria aPL were additionally determined with the established Alegria (ALE), AcuStar (ACU), UniCap (UNI), and AESKULISA (AES) systems and non-criteria aPL with the AES system. Diagnostic performance was evaluated with a gold standard for criteria aPL derived from the results of the four established assays via latent class analysis and with the clinical diagnosis as gold standard for non-criteria aPL.

Results

Assay performance of the LIA for criteria aPL was comparable to that of ALE, ACU, UNI, and AES. For non-criteria aPL, sensitivities of the LIA for aPA-, aPI-, aPS-IgG and aPA-IgM were significantly higher and for aPC-, aPE-, aAnnV-IgG and aPC- and aPE-IgM significantly lower than AES. Specificities did not differ significantly.

Conclusions

The LIA constitutes a valuable diagnostic tool for aPL profiling. It offers increased sensitivity for the detection of aPL against anionic phospholipids. In contrast, ELISAs exhibit strengths for the sensitive detection of aPL against neutral phospholipids.

Clinical performance of non-criteria antibodies to phospholipids in Chinese patients with antiphospholipid syndrome

BACKGROUND

Increasing evidence suggests the role of non-criteria aPLs as important supplements to the current criteria aPLs in APS. In this study, we evaluated the clinical performance of a panel of non-criteria antibodies to phospholipid antigens, including, phosphatidylserine (aPS), phosphatidylinositol (aPI), sphingomyelin (aSM), phosphatidylcholine (aPC) and phosphatidylethanolamine (aPE) in a well-defined Chinese APS cohort.

METHODS

A total of 229 subjects were tested, including 86 patients with APS, 104 disease controls (DCs) and 39 healthy controls (HCs). Serum IgG/IgM aCL, IgG/IgM aβ2GP1, IgG/IgM aPS, IgG/IgM aPI, IgG/IgM aSM, IgG/IgM aPC, and IgG/IgM aPE were tested by ELISA.

RESULTS

The presence of aPE, aPS, aPI, aPC, and aSM in patients with APS and Disease Controls were 8.1% (7/86) and 1.0% (1/104), 37.2% (32/86) and 9.6% (10/104), 50.0% (43/86) and 8.7% (9/104), 23.3% (20/86) and 1.0% (1/104), and 18.6% (16/86) and 1.9% (2/104), respectively. In criteria aPLs, aCL IgG demonstrated the highest positive likelihood ratio (LR+) of 35.75, followed by LA (LR+ of 13.51) and aCL IgM (LR+ of 11.64). In non-criteria aPLs, aPC IgG demonstrated the highest LR+ of 24.94 followed by aSM IgM (LR+ of 14.97). Importantly, the non-criteria aPLs were detected in 18.8% (3/16) of seronegative APS patients. The criteria aPLs, including LA, IgG aCL and IgG aβ2GPI, were significantly correlated with both arterial thrombosis and venous thrombosis, while the non-criteria aPLs, including IgG aPS, IgM aPS, IgG aPI and IgG aPC were significantly associated with arterial thrombosis but not venous thrombosis.

CONCLUSIONS

In summary, our findings indicate that those non-criteria aPLs may be particularly helpful for patients in whom APS is highly suspected, but conventional aPLs are repeatedly negative as well as for predicting APS patients with arterial thrombosis.

Pathogenesis of antiphospholipid syndrome: recent insights and emerging concepts

Introduction: Even though our understanding of the antiphospholipid syndrome (APS) has improved tremendously over the last decades, we are still not in a position to replace symptomatic anticoagulation by pathogenesis based causal treatments. Areas covered: Recent years have provided further insights into pathogenetically relevant mechanisms. These include a differentiation of pathogenic subtypes of antiphospholipid antibodies (aPL), novel mechanisms modulating disease activity, for example, extracellular vesicles and microRNA, and novel players in pathogenesis, for example, neutrophils and neutrophil extracellular traps (NETs). Expert commentary: It is evident that aPL induce a proinflammatory and procoagulant state and recent data suggest that different aPL species activate different signaling pathways which sometimes converge into a common cellular response. This implies that presence of more than one aPL species may disproportionally increase the risk for the major manifestations of APS, that is, thrombosis and fetal loss. Further delineation of the pathogenic mechanisms will hopefully provide clues to causal rather than symptomatic treatments of APS.

Detection of annexin A8 antibodies in serum of patients with antiphospholipid syndrome

Introduction

Antibodies specific for annexin A8 (AnxA8) have not been investigated in patients suffering from antiphospholipid syndrome (APS) yet. The aim of this study was to compare the presence of AnxA8 antibodies in serum of APS patients with that of age-matched healthy controls and to investigate whether AnxA8 antibodies are potential biomarkers for APS.

Materials and methods

We enrolled 22 APS patients and 22 healthy controls in this case-control study. We used sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblot to investigate the presence of AnxA8 antibodies, and we applied enzyme-linked immunosorbent assay to investigate the presence of cardiolipin (CL) and beta-2-glycoprotein I (ß2GPI) antibodies.

Results

The serum of 9/22 APS patients showed AnxA8 IgG isotype antibody reactivity compared to serum of 2/22 healthy controls (P = 0.034). When we also included weak immunoblot signals, 12/22 APS patients exhibited AnxA8 IgG isotype antibody reactivity compared to 3/22 healthy controls (P = 0.005). We also investigated the presence of AnxA8 IgM isotype antibodies in the serum of APS patients but found no statistically significant difference between the APS patient group and healthy control group (P = 0.500). We further investigated the presence of ß2GPI and CL IgG and IgM isotype antibodies. AnxA8 IgG isotype antibodies were present in APS patients in a similar frequency as the APS “criteria” antibody against CL (P = 0.764).

Conclusion

We demonstrated that AnxA8 IgG isotype antibodies are potential biomarkers for the diagnosis of APS.

Lupus anticoagulant testing using two parallel methods detects additional cases and predicts persistent positivity

Background:

Antiphospholipid antibody syndrome (APS) is characterized by laboratory evidence of antiphospholipid antibodies (aPL) [e.g. lupus anticoagulant (LA), anticardiolipin (ACL), and/or antiβ2-glycoprotein I (aB2GPI)] in a clinical setting of thrombosis or pregnancy morbidity. The International Society on Thrombosis and Haemostasis recommends two different testing modalities to detect LA. To evaluate these recommendations in a clinical setting, our hospital, a tertiary care center with a specialized coagulation laboratory, added the dilute Russell’s viper venom time to be performed in parallel with the PTT-lupus anticoagulant to detect LA.

Methods:

Results of aPL testing were collected on all patients who had LA testing for one year. Chart review was performed to correlate LA results with ACL, aB2GPI, and clinical history.

Results:

Patients who were initially LA positive by both PTT-lupus anticoagulant and dilute Russell’s viper venom time were more likely to be persistently positive. Patients who were positive for ACL and aB2GPI were likely to be positive by both LA methodologies. No single method was absolutely sensitive, as cases of APS were detected by PTTLA only, DRVVT only, and both methods.

Conclusions:

The addition of a second testing method for LA provides additional diagnostic information and may be helpful in stratifying risk of thrombosis.

Anti-phospholipid Antibodies and Smoking: An Overview

Antiphospholipid syndrome is characterized by the presence of antiphospholipid antibodies, specifically lupus anticoagulant, anticardiolipin antibodies, and anti-β2 glycoprotein-I antibodies. Antiphospholipid syndrome can occur on its own or in association with other autoimmune diseases, most commonly systemic lupus erythematosus (SLE). A connection between cigarette smoking and anti-phospholipid antibodies (aPL) was first reported in the late1980s. Systemic lupus erythematosus patients with aPL are more likely to be smokers than those without aPL. These patients have a particularly high frequency of vascular events. Recently, a potential link between periodontitis, tobacco, and aPL has been proposed. Research has also suggested that periodontitis and Porphyromonas gingivalis infection are associated with citrullination through the action of peptidylarginine deiminase. A strong correlation between smoking and the presence of citrillunated autoantibodies, which are characteristic of rheumatoid arthritis, has also been observed. While many studies have investigated possible links between infection and aPL in patients with autoimmune diseases, the association of smoking with aPL has not been systematically examined. The fact that both aPL and tobacco are risk factors for thrombosis has complicated efforts to evaluate these factors separately. Also, there has been great variability in measurement techniques, and laboratories lack routine methods for differentiating transient and persistent aPL; both of these factors can make interpretation of autoantibody results quite challenging. This review summarizes the clinical evidence supporting a posited link between aPL and smoking, both in patients with a systemic autoimmune disease and in patients with other medical conditions.

Antibodies to phosphatidylserine/prothrombin (aPS/PT) enhanced the diagnostic performance in Chinese patients with antiphospholipid syndrome

Background:

Increasing evidence has highlighted the role of non-criteria antiphospholipid antibodies (aPLs) as important supplements to the current criteria aPLs for the diagnosis of antiphospholipid syndrome (APS). In this retrospective study, we evaluated the clinical relevance of antibodies to phosphatidylserine/prothrombin (aPS/PT) in Chinese patients with APS.

Methods:

A total of 441 subjects were tested, including 101 patients with primary APS (PAPS), 140 patients with secondary APS (SAPS), 161 disease controls (DCs) and 39 healthy controls (HCs). Serum IgG/IgM aPS/PT was determined by ELISA.

Results:

The levels of IgG/IgM aPS/PT were significantly increased in patients with APS compared with DCs and HCs. IgG and IgM aPS/PT were present in 29.7% and 54.5% of PAPS, and 42.1% and 53.6% of SAPS, respectively. For diagnosis of APS, IgG aCL exhibited the highest positive likelihood ratio (LR+) of 21.60, followed by LA (13.84), IgG aβ2GP1 (9.19) and IgG aPS/PT (8.49). aPS/PT was detected in 13.3% of seronegative PAPS patients and 31.3% of seronegative SAPS patients. LA exhibited the highest OR of 3.64 in identifying patients with thrombosis, followed by IgG aCL (OR, 2.63), IgG aPS/PT (OR, 2.55) and IgG aβ2GP1 (OR, 2.33). LA and IgG aCL were correlated with both arterial and venous thrombosis, whereas IgG aPS/PT and IgG aβ2GP1 correlated with venous or arterial thrombosis, respectively.

Conclusions:

Our findings suggest that the inclusion of IgG/IgM aPS/PT may enhance the diagnostic performance for APS, especially in those in whom APS is highly suspected, but conventional aPLs are repeatedly negative. In addition, IgG aPS/PT may contribute to identify patients at risk of thrombosis.

Antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the presence of antiphospholipid antibodies, such as lupus anticoagulant, anticardiolipin antibodies and anti-β2-glycoprotein 1 antibodies. APS can present with a variety of clinical phenotypes, including thrombosis in the veins, arteries and microvasculature as well as obstetrical complications. The pathophysiological hallmark is thrombosis, but other factors such as complement activation might be important. Prevention of thrombotic manifestations associated with APS includes lifestyle changes and, in individuals at high risk, low-dose aspirin. Prevention and treatment of thrombotic events are dependent mainly on the use of vitamin K antagonists. Immunosuppression and anticomplement therapy have been used anecdotally but have not been adequately tested. Pregnancy morbidity includes unexplained recurrent early miscarriage, fetal death and late obstetrical manifestation such as pre-eclampsia, premature birth or fetal growth restriction associated with placental insufficiency. Current treatment to prevent obstetrical morbidity is based on low-dose aspirin and/or low-molecular-weight heparin and has improved pregnancy outcomes to achieve successful live birth in >70% of pregnancies. Although hydroxychloroquine and pravastatin might further improve pregnancy outcomes, prospective clinical trials are required to confirm these findings.

Pathophysiological insights into the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is characterized by venous and/or arterial thrombosis and severe pregnancy morbidity in presence of antiphospholipid antibodies (aPL). While there is compelling evidence that aPL cause the clinical manifestations of APS, the underlying mechanisms are still a matter of scientific debate. This is mainly related to the broad heterogeneity of aPL. There are three major types of aPL: The first one binds to (anionic) phospholipids, e.g. cardiolipin, in absence of other factors (cofactor independent aPL). The second type binds to phospholipids only in presence of protein cofactors, e.g. ß2-glycoprotein I (ß2GPI) (cofactor dependent aPL). The third type binds to cofactor proteins directly without need for phospholipids. It is widely believed that cofactor independent aPL (type 1) are associated with infections and, more importantly, non-pathogenic, while pathogenic aPL belong to the second and in particular to the third type. This view, in particular with regard to type 1 aPL, has not been undisputed and novel research data have shown that it is in fact untenable. We summarize the available data on the pathogenetic role of aPL and the implications for diagnosis of APS and future research.

Investigating in utero fetal death: outcome of internal medicine consultation

AIM

The objectives were to determine the frequency of in utero fetal death (IUFD) related to placental disorders and to assess the frequency of antiphospholipid antibodies syndrome (APS) among women referred to the internal medicine department.

METHODOLOGY

A retrospective clinical study conducted in Rennes University Hospital, France. From January 2007 to December 2014, 53 women who presented an IUFD at 14 weeks or more of gestational age were included. The main cause for each IUFD was determined by expert agreement. Primary outcome was to analyze the final etiologies diagnosed and the prevalence of IUFD related to placental disorders. Secondary outcomes included the frequency of APS among patients with IUFD of placental origin and the pathological and clinical features associated with APS.

RESULTS

IUFD resulted from placental disorders in 36/53 (68%) patients, and remained unexplained in 11 cases (20.8%). Among the 36 patients with placental disorders, APS was diagnosed in five (13.9%) cases, and four (11.1%) patients were considered as having 'non-criteria' APS. History of thrombosis (P = 0.001) and placental infarcts (P = 0.047) were significantly associated with APS.

CONCLUSION

Placental disorders were the major cause for IUFD in patients who were referred to internal medicine specialists. Importantly, APS was seldom found in patients with placental disorders. Venous thromboembolism history and placental infarcts were both significantly associated with APS. Further studies are needed in order to deepen our understanding of the physiopathology of placental disorders and its underlying causes among non-APS women, and to determine the best treatment regimen for future pregnancies.

Incidence of thromboembolic events in asymptomatic carriers of IgA anti ß2 glycoprotein-I antibodies

BACKGROUND

The antiphospholipid syndrome (APS) is defined by simultaneous presence of vascular clinical events and antiphospholipid antibodies (aPL). The aPL considered as diagnostics are lupus anticoagulant and antibodies anticardiolipin (aCL) and anti-ß2 glycoprotein-I (aB2GP1). During recent years, IgA aB2GP1 antibodies have been associated with thrombotic events both in patients positive, and mainly negative for other aPL, however its value as a pro-thrombotic risk-factor in asymptomatic patients has not been well defined.

OBJECTIVE

To test the role of IgA anti B2GP1 as a risk factor for the development of APS-events (thrombosis or pregnancy morbidity) in asymptomatic population with a 5-year follow-up.

METHODS

244 patients isolated positive for anti-beta2-glycoprotein I IgA (Group-1 study) and 221 negative patients (Group-2 control) were studied. All the patients were negative for IgG and IgM aCL.

RESULTS

During the follow-up, 45 patients (9.7%) had APS-events, 38 positive for IgA-aB2GP1 and 7 negative (15.6% vs 3.2%, p<0.001). The incidence rate of APS-events was 3.1% per year in IgA-aB2GP1 positive patients and 0.6% per year in the control group. Arterial thrombosis were the most frequent APS-events (N = 25, 55%) and were mainly observed in Group-1 patients (21 vs 4, p = 0.001). Multivariate analysis were shown as independent risk-factors for the development of APS-events, age, sex (men) and presence of IgA-aB2GP1 (odds ratio 5.25, 95% CI 2.24 to 12.32).

CONCLUSION

The presence of IgA-aB2GP1 in people with no history of APS-events is the main independent risk factor for the development of these types of events, mainly arterial thrombosis.

A importância de reconhecer a síndrome antifosfolípide na medicina vascular

A síndrome antifosfolipíde (SAF) é uma doença autoimune sistêmica caracterizada por trombose arterial ou venosa recorrente e/ou morbidade gestacional e pela presença dos anticorpos antifosfolipídeos, podendo apresentar outras manifestações vasculares, como microangiopatia, arteriopatia crônica e SAF catastrófica. Determinados testes laboratoriais para a síndrome (por exemplo, o anticoagulante lúpico) podem sofrer interferência do uso de medicações anticoagulantes, dificultando o diagnóstico. A fisiopatologia da SAF é complexa, sendo enumerados no texto diversos mecanismos patogênicos relacionados à coagulação, ao endotélio e às plaquetas. Por fim, discutimos o tratamento da SAF de acordo com a presença e o tipo de manifestações clínicas, o uso dos anticoagulantes orais diretos e o manejo perioperatório de pacientes com SAF.

Pathogenesis and management of antiphospholipid syndrome

Antiphospholipid antibodies are a heterogeneous group of autoantibodies that have clear associations with thrombosis and pregnancy morbidity, and which together constitute the 'antiphospholipid syndrome' (APS). However, the pathophysiology of these complications is not well understood and their heterogeneity suggests that more than one pathogenic process may be involved. Diagnosis remains a combination of laboratory analysis and clinical observation but there have been significant advances in identifying specific pathogenic features, such as domain I-specific anti-β2-glycoprotein-I antibodies. This in turn has pointed to endothelial and complement activation as important factors in the pathogenesis of APS. Consequently, although anticoagulation remains the standard treatment for thrombotic APS and during pregnancy, the realisation that these additional pathways are involved in the pathogenesis of APS has significant implications for treatment: agents acting outside the coagulation system, such as hydroxychloroquine for pregnancy complications and sirolimus as an inhibitor of the mammalian target of rapamycin (mTOR) pathway, are now under evaluation and represent a radical change in thinking for haematologists. Conventional anticoagulation is also under challenge from new, direct acting anticoagulants. This review will provide a comprehensive overview of the evolving understanding of APS pathogenesis and how this and novel therapeutics will alter diagnosis and management.

Evaluation of Autoantibodies in Patients with Primary and Secondary Sjogren's Syndrome

Background:

Antibodies to salivary gland protein 1 (SP1), carbonic anhydrase 6 (CA6) and parotid secretory protein (PSP) were discovered in an animal model of Sjogren’s syndrome (SS). Their expression was noted in patients with SS, especially those with lower focus scores on lip biopsies and those with early disease lacking antibodies to Ro and La.

Objective:

The current studies evaluated these autoantibodies in patients with long-standing SS expressing high levels of anti-Ro antibodies and in patients with Sjogren’s syndrome secondary to systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and mixed connective tissue disease (MCTD).

Method:

Sera were obtained from patients and evaluated by ELISA for IgG, IgA and IgM antibodies to SP1, CA6 and PSP.

Results:

IgA anti-CA6 antibodies were noted in 38% of these patients, but anti-SP1, CA6 and PSP IgM or IgG antibodies were identified only in a minority of patients. In patients with secondary SS, antibodies to SP1/CA6/PSP were more sensitive and specific than anti-Ro .

Conclusion:

While more studies are needed, antibodies to SP1, CA6 and PSP provide valuable markers for the diagnosis of primary and secondary SS, especially early in the course of the disease.

Anoctamins/TMEM16 Proteins: Chloride Channels Flirting with Lipids and Extracellular Vesicles

Anoctamin (ANO)/TMEM16 proteins exhibit diverse functions in cells throughout the body and are implicated in several human diseases. Although the founding members ANO1 (TMEM16A) and ANO2 (TMEM16B) are Ca²⁺-activated Cl^- channels, most ANO paralogs are Ca²⁺-dependent phospholipid scramblases that serve as channels facilitating the movement (scrambling) of phospholipids between leaflets of the membrane bilayer. Phospholipid scrambling significantly alters the physical properties of the membrane and its landscape and has vast downstream signaling consequences. In particular, phosphatidylserine exposed on the external leaflet of the plasma membrane functions as a ligand for receptors vital for cell-cell communication. A major consequence of Ca²⁺-dependent scrambling is the release of extracellular vesicles that function as intercellular messengers by delivering signaling proteins and noncoding RNAs to alter target cell function. We discuss the physiological implications of Ca²⁺-dependent phospholipid scrambling, the extracellular vesicles associated with this activity, and the roles of ANOs in these processes.

Association between antiphospholipid antibodies and arterial thrombosis in patients with rheumatoid arthritis

OBJECTIVES

Antiphospholipid antibodies (aPL) are present in a proportion of patients with rheumatoid arthritis but their clinical significance remains unclear. We investigated the association between aPL and thrombotic events in rheumatoid arthritis patients.

METHODS

In this cross-sectional study, aPL profiles were evaluated in 376 rheumatoid arthritis patients in accordance with the standard guidelines. Clinical and radiographic data were retrospectively collected.

RESULTS

aPL were identified in 39 patients (10.4%). Lupus anticoagulant was the most common subtype (n = 25, 6.6%); anti-cardiolipin antibodies and anti-β₂ glycoprotein I antibodies were detected in six and 12 patients (1.6% and 3.2%), respectively. Compared to the aPL-negative group, aPL-positive patients included more male patients (41.0% vs. 15.4%, P < 0.001) and more smokers (41.0% vs. 16.0%, P = 0.001). There was no difference between the two groups in age, disease duration and body mass index, or the frequency of diabetes, hypertension or dyslipidaemia. Of note, arterial thromboses were more common in the aPL-positive than the aPL-negative group (12.8% vs. 2.1%, P = 0.004), whereas the frequency of venous thrombosis did not differ between the two groups (0.0% vs. 0.9%, P = 1.000). On multivariate regression analysis, aPL, age, hypertension, dyslipidaemia and baseline C-reactive protein level were independently associated with arterial thrombotic events (all P values < 0.05).

CONCLUSION

aPL was found in a subset of rheumatoid arthritis patients, who were more often smokers, and aPL was independently associated with development of arterial thrombosis. This result suggests that aPL may contribute to an increased risk of arterial thrombosis in rheumatoid arthritis patients.

The role of anti-phospholipid antibodies in autoimmune reproductive failure

Anti-phospholipid antibodies (aPL) are autoantibodies that are associated with thrombosis and a range of pregnancy complications including recurrent pregnancy loss and pre-eclampsia. The three clinically relevant, well-characterized aPL are anti-cardiolipin antibodies, lupus anticoagulant and anti-beta-2-glycoprotein I (β2GPI) antibodies. aPL do not bind directly to phospholipids but instead bind to a plasma-binding ‘cofactor’. The most extensively studied cofactor is β2GPI, whose role in pregnancy is not fully elucidated. Although the pathogenicity of aPL in recurrent pregnancy loss is well established in humans and animal models, the association of aPL with infertility does not appear to be causative. aPL may exert their detrimental effects during pregnancy by directly binding trophoblast cells of the placenta, altering trophoblast signalling, proliferation, invasion and secretion of hormones and cytokines, and by increasing apoptosis. Heparin is commonly used to treat pregnant women with aPL; however, as thrombotic events do not occur in the placentae of all women with aPL, it may exert a protective effect by preventing the binding of aPL to β2GPI or by acting through non-thrombotic pathways. The aim of this review is to present evidence summarizing the current understanding of this field.