The first thrombotic event in purely obstetric antiphospholipid syndrome patients and in antiphospholipid antibody carriers: comparison of incidence and characteristics

Antiphospholipid antibody carriers and patients with quiescent antiphospholipid syndrome show persistent subclinical complement activation

OBJECTIVES

Complement activation has been advocated as one mechanism by which aPLs can induce thrombosis. In patients with catastrophic APS or re-thrombosis, enhanced complement activation has been shown, even in the quiescent phase of the disease. We aimed to assess complement activation and to investigate its association with clinical variables in aPL-positive patients with a favourable disease course.

METHODS

Subjects with at least two consecutive positive aPL results obtained ≥12 weeks apart were enrolled. They were subjects without a history of thrombosis or pregnancy morbidity (aPL carriers), patients with pregnancy morbidity alone, i.e. obstetric APS patients (OAPS patients), and/or patients with arterial, venous, or small-vessel thrombotic APS (TAPS patients); for enrolment, all patients were required to have been free of symptoms for ≥2 years. Patients affected with systemic autoimmune diseases were excluded. Healthy age- and sex-matched subjects were included as controls. Plasma C5a and C5b-9 levels were assessed by commercially available ELISA assays. The non-parametric Mann-Whitney test and Spearman's correlation were applied.

RESULTS

Thirty-seven OAPS patients, 38 TAPS patients, 42 aPL carriers and 30 healthy subjects were enrolled. The median C5a and C5b-9 levels were significantly higher in quiescent aPL-positive patients (OAPS, TAPS, aPL carriers) compared with controls: C5a ng/ml 10.61 [interquartile range (IQR) 6.87-15.46] vs 4.06 (2.66-7.35), P < 0.001; C5b-9 ng/ml 283.95 (175.8-439.40) vs 165.90 (124.23-236.8), P < 0.001. Similar C5a and C5b-9 levels were observed in OAPS and TAPS patients and aPL carriers. A positive correlation between the median C5b-9 levels and the number of aPL-positive tests was found (P = 0.002).

CONCLUSION

The persistence of aPL antibodies is associated with a persistent subclinical activation of the complement cascade.

Pregnancy in antiphospholipid syndrome: what should a rheumatologist know?

This review focuses on the management of reproductive issues in women who have antiphospholipid syndrome (APS) or are carriers of antiphospholipid antibodies (aPL). The importance of aPL detection during preconception counselling relies on their pathogenic potential for placental insufficiency and related obstetric complications. The risk of adverse pregnancy outcomes can be minimized by individualized risk stratification and tailored treatment aimed at preventing placental insufficiency. Combination therapy of low-dose acetylsalicylic acid and heparin is the mainstay of prophylaxis during pregnancy; immunomodulation, especially with hydroxychloroquine, should be considered in refractory cases. Supplementary ultrasound surveillance is useful to detect fetal growth restriction and correctly tailor the time of delivery. The individual aPL profile must be considered in the stratification of thrombotic risk, such as during assisted reproduction techniques requiring hormonal ovarian stimulation or during the follow-up after pregnancy in order to prevent the first vascular event.

Interaction between endothelial cell-derived extracellular vesicles and monocytes: A potential link between vascular thrombosis and pregnancy-related morbidity in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease driven by a wide group of autoantibodies primarily directed against phospholipid-binding proteins (antiphospholipid antibodies). APS is defined by two main kinds of clinical manifestations: vascular thrombosis and pregnancy-related morbidity. In recent years, in vitro and in vivo assays, as well as the study of large groups of patients with APS, have led some authors to suggest that obstetric and vascular manifestations of the disease are probably the result of different pathogenic mechanisms. According to this hypothesis, the disease could be differentiated into two parallel entities: Vascular APS and obstetric APS. Thus, vascular APS is understood as an acquired thrombophilia in which a generalised phenomenon of endothelial activation and dysfunction (coupled with a triggering factor) causes thrombosis at any location. In contrast, obstetric APS seems to be due to an inflammatory phenomenon accompanied by trophoblast cell dysfunction. The recent approach to APS raises new issues; for instance, the mechanisms by which a single set of autoantibodies can lead to two different clinical entities are unclear. This review will address the monocyte, a cell with well-known roles in haemostasis and pregnancy, as a potential participant in vascular thrombosis and pregnancy-related morbidity in APS. We will discuss how in a steady state the monocyte-endothelial interaction occurs via extracellular vesicles (EVs), and how antiphospholipid antibodies, by inducing endothelial activation and dysfunction, may disturb this interaction to promote the release of monocyte-targeted procoagulant and inflammatory messages.

Extracellular vesicles released upon stimulation with antiphospholipid antibodies: An actual direct procoagulant mechanism or a new factor in the lupus anticoagulant paradox?

Antiphospholipid antibodies (aPL) lead to a hypercoagulable state in vivo. Paradoxically, some of these autoantibodies perform as inhibitors of the coagulation cascade in vitro (a phenomenon referred to as "lupus anticoagulant"). The presence of lupus anticoagulant has been related to an increased quantity of plasma extracellular vesicles, which may constitute a direct procoagulant mechanism in antiphospholipid syndrome. This study investigates whether or not endothelial cell-derived extracellular vesicles released upon stimulation with aPL (aPL-EDEVs) are related to a higher direct coagulation activity. Using an in vitro model of endothelium, flow cytometry and a recalcified plasma-based assay, we found that the coagulation activity of aPL-EDEVs is mainly conditioned by the lupus anticoagulant-like activity of autoantibodies. Nevertheless, in the presence of β2 glycoprotein I, a cofactor of aPL during the stimulation of endothelial cells, the coagulation activity of EDEVs is restored in a mitogen-activated protein kinase kinases 1 and 2 (MEK1/2)-dependent manner. This phenomenon was especially evident when using immunoglobulins G from patients with vascular and obstetric primary antiphospholipid syndrome who manifest refractoriness to treatment. Our findings suggest that the role of aPL-EDEVs in the antiphospholipid syndrome-related hypercoagulable state may not rely on their capacity to enhance clotting directly. While β2 glycoprotein I performs as a procoagulant cofactor and restores the coagulation activity of extracellular vesicles via MEK1/2 pathway, proportionally, autoantibodies interact with aPL-EDEVs and exhaust their coagulation properties. Further analysis is required to establish whether lupus anticoagulant-like autoantibodies opsonise extracellular vesicles and whether opsonised vesicles may lead to thrombosis by indirect means.

Antiphospholipid Antibodies in Pregnancy: Maternal and Neonatal Implications

Antiphospholipid antibodies (aPL Abs) have long been associated with the occurrence of certain specific pregnancy morbidities, affecting both mother and fetus. Antithrombotic-based prophylactic regimens are the standard of care. Their intensity is modulated by the thrombotic history and has greatly improved the prognosis related to spontaneous morbidity. Observational studies show that this treatment is still associated with the persistence of excess of late-pregnancy placental diseases, calling for new or complementary developments, yet to be validated. Rigorous prospective multicentric validation of clinical and laboratory parameters capable of identifying those women and fetuses at a risk of pejorative evolution, thus early prognosis, is a priority issue. These will make it possible to develop customized treatments and test them. Furthermore, there are still concerns, particularly neurodevelopmental ones, about children born to aPL Ab-positive mothers, and clarification based on regular, more systematic evaluations is required. Even after pregnancy, women with a pure obstetrical antiphospholipid syndrome are at a greater risk of venous and arterial thrombosis over time, and prevention needs to be improved. These women also appear to develop more psychiatric and mood disorders. Central nervous system imaging using high-resolution techniques has shown subtle impairments in the white matter, associated with the most pathogenic aPL Abs and the clinical significance of this is under investigation. These mothers also seem to develop an excess of cancers. The systemic impact of aPL Abs is gradually being suspected, although this requires further evidence, and prevention should be envisaged.

Clinical and therapeutic value of the adjusted Global Antiphospholipid Syndrome Score in primary obstetric antiphospholipid syndrome

OBJECTIVES

(1) To assess the clinical utility of the adjusted global antiphospholipid syndrome score (aGAPSS) to predict new obstetric events during follow-up in primary obstetric antiphospholipid syndrome (POAPS) patients under standard-of-care treatment (SC) based on the use of low-dose aspirin (LDA) + heparin and (2) to study the risk of a first thrombotic event and to evaluate whether stratification according to this score could help to identify POAPS patients who would benefit from long-term thromboprophylaxis.

METHODS

This is a retrospective, multicentre study. 169 women with POAPS were evaluated for the presence of a new obstetric event and/or a first thrombotic event during follow-up [time period: 2008-2020, median: 7 years (6-12 years)]. The outcomes of 107 pregnancies from these POAPS patients with SC were studied to evaluate relapses. Simple and multivariable logistic regression analyses were performed.

RESULTS

Regarding obstetric morbidity, only triple positivity for antiphospholipid antibodies (aPLs) [OR = 8.462 (95% CI: 2.732-26.210); p < 0.0001] was found to be a strong risk factor independently associated with treatment failure. On the other hand, triple positivity for aPLs [OR=10.44 (95% CI: 2.161-50.469), p = 0.004] and an aGAPSS ≥7 [OR = 1.621 (95% CI: 1.198-2.193), p = 0.002] were independent risk factors associated with a first thrombotic event. LDA was marginally associated with a decrease in the risk of thrombosis only in patients with aGAPSS ≥ 7 (p = 0.048).

CONCLUSION

aGAPSS appears to be useful in predicting the occurrence of a first thrombotic event in POAPS patients, and these stratification of patients could be helpful in selecting patients who would benefit from thromboprophylaxis with LDA.

The high prevalence of abnormal MRI findings in non-neuropsychiatric patients with persistently positive antiphospholipid antibodies

OBJECTIVES

Thrombosis occurring in the central nerve system is common in antiphospholipid syndrome (APS) patients, leading to neuropsychiatric symptoms. We investigated the prevalence of silent brain abnormalities on magnetic resonance imaging (MRI) in primary antiphospholipid syndrome (PAPS) patients and antiphospholipid antibodies (aPL) carriers and assessed the association between the vascular risk factors, aPL profile, clinical manifestations, and MRI abnormalities.

METHODS

We consecutively included 44 PAPS patients, 24 aPL carriers and 23 healthy controls with comparable age and gender in a single-center, observational cross-sectional study. None of the patients had a history of stroke, TIA, migraine, dementia, epilepsy and bipolar disorders. On cerebral MRI, we assessed the imaging features and location of abnormality. Multivariate analysis was performed to identify the risk factors contributing to the MRI abnormalities.

RESULTS

38 (55.88%) patients persisted abnormal MRI findings, while only one healthy control showed some abnormalities in the MR findings. Lacunes were the most frequent MRI abnormality in aPL (+) group (31/68, 45.59%), which were followed by white matter hyperintensities (20/68, 29.41%). In all study population, age (OR = 1.086, p= 0.016) and LA positivity (OR = 5.191, p= 0.002) were the independent associated factors with the brain MRI abnormalities. When analyzed only in the aPL (+) group, age (OR = 1.116, p= 0.007), female gender (OR = 7.519, p= 0.025) and thrombocytopenia (OR = 8.336, p= 0.047) were the significant independent risk factors with abnormal MRI.

CONCLUSIONS

PAPS patients and aPL carriers showed a high prevalence of brain MRI abnormalities, indicating an increased cerebrovascular risk, which emphasized attention to silent cerebral lesions in persistently aPL positive patients.