Recent advances in understanding antiphospholipid syndrome

Antiphospholipid Syndrome and Catastrophic Antiphospholipid Syndrome: A Comprehensive Review of Pathogenesis, Clinical Features, and Management Strategies

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by the presence of antiphospholipid antibodies (aPLs) that predispose individuals to thrombotic events and pregnancy-related complications. APS can occur as a primary condition or in association with other autoimmune diseases, most commonly systemic lupus erythematosus (SLE). Catastrophic APS (CAPS) is a rare, severe variant of APS, marked by rapid-onset, widespread thrombosis leading to multi-organ failure, often triggered by infections, surgical procedures, or cessation of anticoagulation therapy. Both APS and CAPS present significant clinical challenges due to their potential for severe morbidity and mortality. This comprehensive review aims to provide a detailed overview of the pathogenesis, clinical features, diagnostic criteria, and management strategies for APS and CAPS. The review highlights the immunological mechanisms underlying APS, including the role of aPLs, complement system activation, and endothelial cell dysfunction in developing thrombosis. It also outlines the clinical manifestations of APS, such as venous and arterial thrombosis, pregnancy morbidity, and neurological symptoms, along with the diagnostic criteria based on clinical and laboratory findings. The review delves into its pathogenesis, clinical presentation, and diagnostic challenges in the context of CAPS, emphasizing the need for immediate and intensive therapy to manage this life-threatening condition. Current management strategies for APS, including anticoagulant therapy, immunomodulatory treatments, and specific interventions for pregnancy-related complications, are discussed. The review highlights the importance of a multidisciplinary approach for CAPS, combining anticoagulation, high-dose corticosteroids, plasma exchange, and intravenous immunoglobulin. The review also addresses the prognosis and long-term outcomes for patients with APS and CAPS, underlining the necessity for ongoing monitoring and follow-up to prevent recurrent thrombotic events and manage chronic complications. Finally, future directions in research are explored, focusing on emerging therapies, biomarkers for early diagnosis, and the need for clinical trials to advance the understanding and treatment of these complex syndromes. By enhancing the understanding of APS and CAPS, this review aims to improve diagnosis, treatment, and patient care, ultimately leading to better health outcomes for those affected by these conditions.

Diagnostic performance of aPS/PT antibodies in neuropsychiatric lupus and cardiovascular complications of systemic lupus erythematosus

Background: Systemic lupus erythematosus (SLE) is associated with a constellation of complications affecting multiple organs, including neuropsychiatric manifestations (NPSLE) and ischaemic events, leading to increased long-term morbidity. Antiphospholipid antibodies (aPL) are a major determinant of vascular inflammation and thromboembolic risk. The diagnostic role of anti-phosphatidylserine/prothrombin (aPS/PT) antibodies in this setting is incompletely defined.Aim: To verify whether aPS/PT add to diagnostics and disease stratification in patients with SLE with or without other aPL.Methods: 131 consecutive patients were studied, including 20 patients with SLE and secondary antiphospholipid syndrome (APS). aPS/PT IgG and IgM were assessed through ELISA and patients were stratified based on the presence of other aPL, on their clinical and laboratory features at time of blood sampling and on their clinical history. Synthetic indices of disease activity, chronic damage and cardiovascular risk were calculated at time of venipuncture.Results: Fifty-one (38.9%) patients with SLE had aPS/PT and 15 (11.5%) patients had aPS/PT as the only aPL (aPS/PT-only). aPS/PT-only patients had a significantly higher prevalence of NPSLE than quadruple aPL-negative patients (p = .007). Patients with aPS/PT were more likely to have a history of ischaemia, thrombocytopenia and Libman-Sacks' endocarditis. The presence of aPS/PT also associated with previous accrual of at least one damage item (p = .043), but had limited predictive values for damage progression in the short term.Conclusion: aPS/PT antibodies provide non-redundant information that could contribute to risk assessment and stratification of patients with SLE.

Misunderstandings Between Platelets and Neutrophils Build in Chronic Inflammation

Regulated hemostasis, inflammation and innate immunity entail extensive interactions between platelets and neutrophils. Under physiological conditions, vascular inflammation offers a template for the establishment of effective intravascular immunity, with platelets providing neutrophils with an array of signals that increase their activation threshold, thus limiting collateral damage to tissues and promoting termination of the inflammatory response. By contrast, persistent systemic inflammation as observed in immune-mediated diseases, such as systemic vasculitides, systemic sclerosis, systemic lupus erythematosus or rheumatoid arthritis is characterized by platelet and neutrophil reciprocal activation, which ultimately culminates in the generation of thrombo-inflammatory lesions, fostering vascular injury and organ damage. Here, we discuss recent evidence regarding the multifaceted aspects of platelet-neutrophil interactions from bone marrow precursors to shed microparticles. Moreover, we analyse shared and disease-specific events due to an aberrant deployment of these interactions in human diseases. To restore communications between the pillars of the immune-hemostatic continuum constitutes a fascinating challenge for the near future.

Antiphosphatidylserine/prothrombin complex antibodies as a determinant of prothrombotic plasma fibrin clot properties in patients with antiphospholipid syndrome

BACKGROUND

Antiphosphatidylserine/prothrombin complex (aPS/PT) antibodies are recognized as a marker for antiphospholipid syndrome (APS). Dense and poorly lysable fibrin clots occur in thrombotic APS. Compact clots predict thromboembolism, but determinants of the unfavorable clot phenotype remain unknown in APS. We hypothesized that elevated aPS/PT antibodies determine unfavorable clot features.

METHODS

In a cohort study involving 124 consecutive patients with thrombotic APS, we measured at baseline plasma fibrin clot permeability (Ks ), efficiency of fibrinolysis (clot lysis time, CLT), and turbidity (off anticoagulation) along with immunoglobulin (Ig)G/IgM aPS/PT. During follow-up, symptomatic thromboembolic events were recorded.

RESULTS

Elevated IgG and IgM aPS/PT antibodies >30 international enzyme units (UI) were detected in 54.8% and 42.7% of APS patients, including 76.2% and 54% of lupus anticoagulant- (LA, n = 63) positive patients, respectively. Elevated IgG and IgM aPS/PT antibodies predicted low Ks (lower quartile, <6 × 10-9  cm2 ; odds ratio [OR] = 5.93, 95% confidence interval [CI] 2.09-16.82 and OR = 11.79, 95% CI 4.10-33.92) and prolonged CLT (top quartile, ≥116 min; OR = 4.85, 95% CI 2.42-25.07 and OR = 6.04, 95% CI 2.42-15.07). No such associations were observed for anticardiolipin or β2-glycoprotein I antibodies or LA presence. During follow-up (median 72.5, range 66-83 months), thromboembolic events observed in 32 (26.7%, 4.6%/year) patients were independently predicted by IgG aPS/PT antibodies >30 UI (hazard ratio [HR] = 3.04, 95% CI 1.20-8.88) and low Ks (HR = 3.00, 95% CI 1.41-6.50).

CONCLUSIONS

We identified aPS/PT antibodies as a determinant of denser and poorly lysable plasma fibrin clot formation in APS patients. The association of elevated aPS/PT antibodies with thromboembolism in APS could be at least in part mediated by prothrombotic clot properties.

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

Objectives

aPL are frequently present in SLE. In a well characterized SLE cohort we aimed at investigating the prevalence of aPL and assessing their analytical performance and clinical association by testing criteria specificities including LA, aCL IgG and IgM, anti-β2-glycoprotein 1 (antiβ2GP1) IgG and IgM, as well as the non-criteria aPS-PT IgG and IgM and anti-β2GP1 domain 1 (aD1) IgG.

Methods

We included 178 patients satisfying the ACR SLE classification criteria, from whom 283 samples and thrombotic events were collected longitudinally. Each sample was tested for criteria and non-criteria aPL using validated techniques in a single centre.

Results

All assays provided highly reproducible results. Of the samples, 42.5% were positive for at least one criteria assay, 20.5% showed double positivity and 12.6% triple positivity. All criteria and non-criteria specificities persisted over time. Most antibody titres were only moderately correlated; however, strong correlation was observed on one hand between aD1 IgG, antiβ2GP1 IgG and aCL IgG, and on the other between aPS-PT IgG and LA. aD1 IgG titres were extremely elevated in triple-positive samples. aPS-PT IgG by itself, and jointly with LA, was associated with thrombosis, an association mostly driven by venous thrombotic events.

Conclusions

In this SLE cohort, the non-criteria aPL aD1 IgG and aPS-PT IgG performed differently. aD1 IgG was highly enriched in triple-positive samples, and aPS-PT IgG, jointly with LA, was associated with thrombotic events.

Elevated serum antiphospholipid antibodies in adults with celiac disease

BACKGROUND AND AIMS

An increased incidence of thrombosis is suggested in celiac disease. We explored serum levels of antiphospholipid antibodies in untreated and treated adult celiac disease patients.

METHODS

A cohort of 179 biopsy-proven celiac disease patients (89 untreated, 90 on long-term gluten-free diet) and 91 non-celiac controls underwent clinical examination, assessment of celiac serology and enzyme immunoassay testing for anticardiolipin IgG and IgM, prothrombin IgG, and phosphatidylserine-prothrombin IgG and IgM.

RESULTS

The level of antiphospholipid antibodies was higher in celiac disease patients compared with controls: anticardiolipin IgG 4.9 (0.7-33.8) vs 2.2 (0.4-9.6) U/ml, antiprothrombin IgG 2.9 (0.3-87.8) vs 2.1 (0.5-187.0) U/ml, antiphosphatidylserine-prothrombin IgG 6.9 (0.0-54.1) vs 2.3 (0.5-15.1) U/ml; p < 0.05 for all. Anticardiolipin IgG, antiprothrombin IgG and antiphosphatidylserine-prothrombin IgG were higher in treated compared with untreated patients. The phenotype of celiac disease at presentation (gastrointestinal symptoms, malabsorption or anemia, and extraintestinal symptoms or screen-detected disease) had no effect on the level of serum antiphospholipid antibodies.

CONCLUSION

The serum level of antiphospholipid antibodies is increased in adults with celiac disease. The higher level of antibodies in treated patients suggests that the increase is not gluten-dependent. The prothrombotic role of antiphospholipid antibodies in celiac disease warrants further studies.

Diagnosing antiphospholipid syndrome: 'extra-criteria' manifestations and technical advances

First described in the early 1980s, antiphospholipid syndrome (APS) is a unique form of acquired autoimmune thrombophilia in which patients 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. However, the clinical spectrum of APS encompasses additional manifestations that can affect many organs and cannot be explained exclusively by patients being in a prothrombotic state; clinical manifestations not listed in the classification criteria (known as extra-criteria manifestations) include neurologic manifestations (chorea, myelitis and migraine), haematologic manifestations (thrombocytopenia and haemolytic anaemia), livedo reticularis, nephropathy and valvular heart disease. Increasingly, research interest has focused on the development of novel assays that might be more specific for APS than the current aPL tests. This Review focuses on the current classification criteria for APS, presenting the role of extra-criteria manifestations and lab-based tests. Diagnostic approaches to difficult cases, including so-called seronegative APS, are also discussed.