Changes in serum immunoglobulin G glycosylation patterns for antiphospholipid syndrome patients with lectin microarray.

Antiphospholipid syndrome is a rare autoimmune disease characterized by persistent antiphospholipid antibodies. Immunoglobulin G plays a vital role in disease progression, with its structure and function affected by glycosylation. We aimed to investigate the changes in the serum immunoglobulin G glycosylation pattern in antiphospholipid syndrome patients. We applied lectin microarray on samples from 178 antiphospholipid syndrome patients, 135 disease controls (including Takayasu arteritis, rheumatoid arthritis and cardiovascular disease) and 100 healthy controls. Lectin blots were performed for validation of significant differences. Here, we show an increased immunoglobulin G-binding level of soybean agglutinin (p = 0.047, preferring N-acetylgalactosamine) in antiphospholipid syndrome patients compared with healthy and disease controls. Additionally, the immunoglobulin G from antiphospholipid syndrome patients diagnosed with pregnancy events had lower levels of fucosylation (p = 0.001, recognized by Lotus tetragonolobus) and sialylation (p = 0.030, recognized by Sambucus nigra I) than those with simple thrombotic events. These results suggest the unique serum immunoglobulin G glycosylation profile of antiphospholipid syndrome patients, which may inform future studies to design biomarkers for more accurate diagnosis of antiphospholipid syndrome and even for the prediction of clinical symptoms in patients.

Assessment and comparison of the 2023 ACR/EULAR APS criteria with the revised Sapporo criteria.

OBJECTIVE: To analyze antiphospholipid antibody (aPL)-positive patients using the 2023 American College of Rheumatology/The European Alliance of Associations for Rheumatology (ACR/EULAR) antiphospholipid syndrome (APS) classification criteria and compare the revised Sapporo criteria and the 2023 ACR/EULAR criteria and evaluate whether the 2023 ACR/EULAR criteria provide added value over the revised Sapporo criteria. METHODS: In this descriptive study, 94 aPL-positive patients (with or without APS diagnosis) were identified from two hospital-based registries (Gazi and Hacettepe University). Patients were classified into four groups to compare both criteria sets. These four groups are as follows: (1) patients classified with only the revised Sapporo criteria; (2) patients classified with only the 2023 ACR/EULAR APS criteria; (3) patients classified with both two criteria sets; and (4) patients classified with neither two criteria set. RESULTS: Of the 94 patients, 11 were classified with only the revised Sapporo criteria; one with only the 2023 ACR/EULAR APS criteria; 52 with both criteria sets; and 30 with neither set of criteria. For these 94 patients, the operating characteristics of the 2023 ACR/EULAR APS criteria, using the revised Sapporo criteria as the gold standard, the 2023 ACR/EULAR APS entry criteria demonstrated 100% sensitivity, and the 2023 ACR/EULAR APS classification criteria demonstrated 98% specificity and 82.5% sensitivity. CONCLUSION: The study emphasizes the importance of recognizing differences in clinical manifestations, such as early pregnancy loss without severe preeclampsia (PEC) and/or severe placental insufficiency (PI) and calls for a nuanced discussion on anticardiolipin (aCL) and anti-beta 2-glycoprotein-I (anti-ß2GPI) immunoglobulin G (IgG) cutoff values.

Antiphospholipid antibody-related hepatic vasculitis in a juvenile after non-severe COVID-19: a case report and literature review.

Antiphospholipid antibodies (aPL) are both laboratory evidence and causative factors for a broad spectrum of clinical manifestations of antiphospholipid syndrome (APS), with thrombotic and obstetric events being the most prevalent. Despite the aPL-triggered vasculopathy nature of APS, vasculitic-like manifestations rarely exist in APS and mainly appear associated with other concurrent connective tissue diseases like systemic lupus erythematous. Several studies have characterized pulmonary capillaritis related to pathogenic aPL, suggesting vasculitis as a potential associated non-thrombotic manifestation. Here, we describe a 15-year-old girl who develops hepatic infarction in the presence of highly positive aPL, temporally related to prior non-severe COVID-19 infection. aPL-related hepatic vasculitis, which has not been reported before, contributes to liver ischemic necrosis. Immunosuppression therapy brings about favorable outcomes. Our case together with retrieved literature provides supportive evidence for aPL-related vasculitis, extending the spectrum of vascular changes raised by pathogenic aPL. Differentiation between thrombotic and vasculitic forms of vascular lesions is essential for appropriate therapeutic decision to include additional immunosuppression therapy. We also perform a systematic review to characterize the prevalence and clinical features of new-onset APS and APS relapses after COVID-19 for the first time, indicating the pathogenicity of aPL in a subset of COVID-19 patients.

Predictive factors of psychiatric syndrome in patients with systemic lupus erythematosus.

Introduction: Early detection of neuropsychiatric systemic lupus erythematosus (NPSLE) remains a challenge in clinical settings. Previous studies have found different autoantibodies as markers for NPSLE. This study aimed to describe the distribution of psychiatric syndromes in a group of patients with systemic lupus erythematosus (SLE) and to investigate the association between psychiatric syndromes and specific autoantibodies. Methods: This retrospective study was conducted at a single medical center in China. We reviewed medical records of hospitalized patients with SLE who were consulted by psychiatrists due to potential mental disorders. Results of serum autoantibodies and general laboratory tests were collected. The correlation between clinical variables was examined. Binary logistic regression analyses were used to determine factors related to NPSLE and different psychiatric diagnoses. Results: Among the 171 psychiatric manifestations in 160 patients, 141 (82.4%) were attributed to SLE. Acute confusional state (ACS) had the highest prevalence (57.4%). Anti-cardiolipin (ACL) antibody (X2 = 142.261, p < 0.001) and anti-ß2 glycoprotein I (-ß2GP1) antibody (X2 = 139.818, p < 0.001) varied significantly between groups, with the highest positive rate found in patients with mood disorders (27.3% and 18.2%). SLE disease activity index - 2000 (SLEDAI-2K) score excluding item ACS and item psychosis was a predictor of NPSLE (OR 1.172 [95% CI 1.105 - 1.243]). Conclusions: Disease activity reflected by SLEDAI-2K score is a predictor for NPSLE. Antiphospholipid antibodies are associated with mood disorders in SLE. Further separate investigation of neuropsychiatric disorders is needed in order to better comprehend NPSLE's pathological mechanism.

The clinical relevance of different antiphospholipid antibody profiles in pediatric rheumatology patients.

BACKGROUND: The clinical relevance of different antiphospholipid antibody (aPL) profiles, including low level anticardiolipin (aCL) and anti-ß2-glycoprotein-I (aß2GPI) antibodies, is ill-defined in the pediatric population. Our purpose is to describe the demographic, clinical, and laboratory characteristics of aPL positive pediatric patients based on different aPL profiles. FINDINGS: In this single center retrospective cohort study, based on the screening of our pediatric (age ≤ 18) rheumatology electronic medical records (2016-2022), we identified patients who had at least one "positive" aPL (lupus anticoagulant [LA], aCL IgG/M, or aß2GPI IgG/M) result. Patients were grouped into high- (LA positive and/or aCL/aß2GPI IgG/M > 40U [ELISA]) and low-risk (LA negative and aCL/aß2GPI IgG/M 20-39U) aPL profiles; those with persistently positive aPL were descriptively analyzed for demographic and clinical characteristics. Of 57 included patients, 34 (59%) had initial high- and 23 (40%) had initial low-risk profiles. Based on subsequent aPL results available in 42/57 (74%) patients, 25/27 (93%) in the high-, and 7/15 (47%) in the low-risk groups remained still positive. Of these 32 patients with persistently positive aPL, moderate-to-large vessel or microvascular thrombosis occurred in nine (28%) patients with high-risk and in none with low-risk aPL profiles; non-thrombotic aPL-related manifestations were reported in 15 (47%) patients with persistent aPL positivity. CONCLUSION: An initial high-risk aPL profile was persistent in approximately 90% of our cohort, a third of whom had thrombosis, and half had non-thrombotic aPL manifestations. Our results underscore the need for a large-scale effort to better characterize aPL-related manifestations in pediatric patients with persistent high-risk aPL-profiles.

Low recurrent thrombosis rates in single positive antiphospholipid syndrome regardless of type of anticoagulation.

Thrombotic antiphospholipid syndrome (TAPS) is characterized by thrombosis and persistently positive tests for antiphospholipid antibodies or lupus anticoagulant (LAC). Triple-positive APS has the highest risk of recurrent thrombosis, but no studies have focused on recurrent thrombosis in patients with single-positive TAPS. We conducted a retrospective cohort study of patients with single-positive TAPS diagnosed at Lifespan Health System, Rhode Island, to determine the rates and risk factors for recurrent thrombosis. Between January 2001 and April 2022, 128 patients were assessed who had single-positive APS (LAC = 98, aCL = 21, aß2GPI = 9) and who had been followed for a total of 1453.8 patient-years (median follow-up 3.04 years). The initial antithrombotic regimen was warfarin in 44 %, a direct oral anticoagulant (DOAC) in 34 %, enoxaparin in 2 %, and no antithrombotic therapy or antiplatelet therapy only in 20 %. Recurrent thrombosis occurred in 16 (12.5 %) with a recurrent thrombosis rate of 3.08 per 100 patient-years. Systemic lupus erythematosus was the only variable significantly associated with recurrent thrombosis in a model adjusted for age, sex, body mass index, and type of positive APS test. All 16 patients with recurrent thrombosis were initially treated with warfarin, and, at the time of recurrent thrombosis, 13 patients remained on warfarin and three were off anticoagulation. In conclusion, the recurrent thrombosis rate in single-positive APS is low, and not all patients with a single-positive test may need indefinite anticoagulation with warfarin. Larger prospective studies are required to confirm this finding and establish optimal anticoagulation regimens for low-risk TAPS.

Loss of opportunities in the diagnosis and treatment of primary obstetric antiphospholipid syndrome (POAPS): from theory to reality.

OBJECTIVES: (I) To identify and measure the clinical consequences of a delayed diagnosis in patients with primary obstetric antiphospholipid syndrome (POAPS), in terms of time and events associated to antiphospholipid syndrome (APS), and (II) to evaluate the impact of their treatment status on perinatal outcomes, before and after diagnosis. METHODS: This retrospective multicentre study included 99 POAPS women who were separated in two groups of timelines based on their diagnostic status: group 1: women who met the clinical criteria for POAPS; group 2: included the same patients from group 1 since they meet the laboratory criteria for APS. In group 1, we assessed the following variables: obstetric events, thrombotic events and time (years) to diagnosis of APS. We also compared perinatal outcomes between patients in group 1 vs. group 2. Women in group 2 were treated with standard of care for POAPS. Simple and multivariable logistic regression analyses were performed. RESULTS: Regarding the impact of the delay on diagnosis, a total of 87 APS-related events were recorded: 46 miscarriages, 32 foetal losses and 9 premature deliveries before the 34th week due to preeclampsia, and one thrombosis. The estimated rate of preventable events was 20.58 per year/100 patients. The mean diagnostic delay time was 4.27 years. When we compared both groups during pregnancy, we found that patients in group 1 (no treatment) had a higher association with pregnancy losses [OR = 6.71 (95% CI: 3.59-12.55), p < 0.0001]. CONCLUSION: Our findings emphasize the negative impact of POAPS underdiagnosis on patient health and the critical importance of a timely intervention to improve pregnancy outcomes. Key Points •Our study shows the relevance of underdiagnosis on primary obstetric antiphospholipid syndrome (POAPS). •These patients presented a high risk of APS-related events with each passing year. •Shorter diagnostic delay time was observed in the reference centres.

Eculizumab therapy and complement regulation in a case of resistant catastrophic antiphospholipid syndrome.

Catastrophic antiphospholipid syndrome (CAPS) is a life-threatening form of antiphospholipid syndrome characterised by diffuse arterial and venous thrombosis, in the presence of positive antiphospholipid antibodies. The multiple sites of thrombosis in small, medium and large vessels progress to multiorgan failure, accounting for the high mortality rate associated with CAPS. Unregulated complement activation is increasingly recognised as critical to the pathogenesis of CAPS. Early diagnosis is essential to initiate prompt life-saving treatment with the triple therapy of anticoagulation, immunosuppression and either plasmapheresis or intravenous immunoglobulin. Among other immunosuppressive agents, eculizumab, a complement inhibitor has demonstrated efficacy in treatment-resistant cases.We report an instructive case of a woman presenting with both clinical and laboratory findings consistent with primary CAPS, resistant to initial treatment and responsive to eculizumab, with emphasis on genetic testing and implications for future therapy.

Type I interferon pathway activation across the antiphospholipid syndrome spectrum: associations with disease subsets and systemic antiphospholipid syndrome presentation.

Introduction: While the type I interferon (IFN-I) pathway is crucial in autoimmunity, its role in antiphospholipid antibody (aPL)-positive subjects, including aPL carriers and antiphospholipid syndrome (APS) patients, is poorly understood. This study aims at characterizing IFN-I pathway activation within the spectrum of aPL-positive subsets. Methods: A total of 112 patients [29 aPL carriers, 31 primary APS (PAPS), 25 secondary APS (SAPS), 27 systemic lupus erythematosus (SLE) patients without aPL, and 44 healthy controls (HCs)] were recruited. IFI6, IFI44, IFI44L, MX1, IFI27, OAS1, and RSAD2 gene expression was evaluated in whole blood, and a composite index (IFN score) was calculated. Results: An overall activation of the IFN-I pathway was observed across the entire APS spectrum, with differences among genes based on the specific disease subset. The composite score revealed quantitative differences across subsets, being elevated in aPL carriers and PAPS patients compared to HCs (both p < 0.050) and increasing in SAPS (p < 0.010) and SLE patients (p < 0.001). An unsupervised cluster analysis identified three clusters, and correspondence analyses revealed differences in clusters usage across APS subsets (p < 0.001). A network analysis revealed different patterns characterizing different subsets. The associations between IFN-I pathway activation and clinical outcomes differed across APS subsets. Although no differences in gene expression were observed in systemic APS, the network analyses revealed specific gene-gene patterns, and a distinct distribution of the clusters previously identified was noted (p = 0.002). Conclusion: IFN-I pathway activation is a common hallmark among aPL-positive individuals. Qualitative and quantitative differences across the APS spectrum can be identified, leading to the identification of distinct IFN-I signatures with different clinical values beyond traditional categorization.

Antiphospholipid antibody positive Sneddon syndrome: a case report.

Sneddon syndrome may present with neurological findings such as transient ischemic stroke, strokes, seizures and/or headaches. However, a purplish, spider web-like skin finding called livedo reticularis may accompany the skin and precede neurological findings. Sneddon syndrome often affects women. Since it is vasculopathy affecting small and medium vessels, other organ findings may accompany. We present a 44-year-old Sneddon syndrome patient with monoparesis in her left lower extremity, livedo reticularis on her back and legs, and hypertension.

Antiphospholipid antibodies as potential predictors of disease severity and poor prognosis in systemic lupus erythematosus-associated thrombocytopenia: results from a real-world CSTAR cohort study.

BACKGROUND: To investigate the role of antiphospholipid antibodies (aPLs) in the disease severity and prognosis of SLE-related thrombocytopenia (SLE-TP). METHODS: This multicenter prospective study was conducted based on data from the CSTAR registry. TP was defined as a platelet count<100 × 109/L. Demographic characteristics, platelet count, clinical manifestations, disease activity, and autoantibody profiles were collected at baseline. Relapse was defined as the loss of remission. Bone marrow aspirate reports were also collected. RESULTS: A total of 350 SLE-TP patients with complete follow-up data, 194 (55.4%) were aPLs positive. At baseline, SLE-TP patients with aPLs had lower baseline platelet counts (61.0 × 109/L vs. 76.5 × 109/L, P<0.001), and a higher proportion of moderate to severe cases (24.2% vs. 14.1% ; 18.0% vs. 8.3%, P<0.001). SLE-TP patients with aPLs also had lower platelet counts at their lowest point (37.0 × 109/L vs. 51.0 × 109/L, P = 0.002). In addition, thean increasing number of aPLs types was associated with a decrease in the baseline and minimum values of platelets ( P<0.001, P = 0.001). During follow-up, SLE-TP carrying aPLs had a higher relapse rate (58.2% vs. 44.2%, P = 0.009) and a lower complete response (CR) rate. As the types of aPLs increased, the relapse rate increased, and the CR rate decreased. Furthermore, there was no significant difference in the ratio of granulocytes to red blood cells (G/E), the total number of megakaryocyte and categories. CONCLUSION: SLE-TP patients with positive aPLs had more severe disease a lower remission rate but a higher relapse rate.

Cryo-EM structure and functional basis of prothrombin recognition by a type I antiprothrombin antiphospholipid antibody.

ABSTRACT: Antiprothrombin antibodies are found in antiphospholipid patients, but how they interact with prothrombin remains elusive. Prothrombin adopts closed and open forms. We recently discovered type I and type II antibodies and proposed that type I recognizes the open form. In this study, we report the discovery and structural and functional characterization in human plasma of a type I antibody, POmAb (prothrombin open monoclonal antibody). Using surface plasmon resonance and single-molecule spectroscopy, we show that POmAb interacts with kringle-1 of prothrombin, shifting the equilibrium toward the open form. Using single-particle cryogenic electron microscopy (cryo-EM), we establish that the epitope targeted by POmAb is in kringle-1, comprising an extended binding interface centered at residues R90-Y93. The 3.2-Å cryo-EM structure of the complex reveals that the epitope overlaps with the position occupied by the protease domain of prothrombin in the closed state, explaining the exclusive binding of POmAb to the open form. In human plasma, POmAb prolongs phospholipid-initiated and diluted Russell's viper venom clotting time, which could be partly rescued by excess phospholipids, indicating POmAb is an anticoagulant but exerts a weak lupus anticoagulant effect. These studies reveal the structural basis of prothrombin recognition by a type I antiphospholipid antibody and uncover an exciting new strategy to achieve anticoagulation in human plasma.

Non-criteria antiphospholipid antibodies and calprotectin as potential biomarkers in pediatric antiphospholipid syndrome.

Our study aimed to evaluate the presence, clinical associations, and potential mechanistic roles of non-criteria antiphospholipid antibodies (aPL) and circulating calprotectin, a highly stable marker of neutrophil extracellular trap release (NETosis), in pediatric APS patients. We found that 79% of pediatric APS patients had at least one non-criteria aPL at moderate-to-high titer. Univariate logistic regression demonstrated that positive anti-beta-2 glycoprotein I domain 1 (anti-D1) IgG (p = 0.008), anti-phosphatidylserine/prothrombin (aPS/PT) IgG (p < 0.001), and aPS/PT IgM (p < 0.001) were significantly associated with venous thrombosis. Positive anti-D1 IgG (p < 0.001), aPS/PT IgG (p < 0.001), and aPS/PT IgM (p = 0.001) were also associated with non-thrombotic manifestations of APS, such as thrombocytopenia. Increased levels of calprotectin were detected in children with APS. Calprotectin correlated positively with absolute neutrophil count (r = 0.63, p = 0.008) and negatively with platelet count (r = -0.59, p = 0.015). Mechanistically, plasma from pediatric APS patients with high calprotectin levels impaired platelet viability in a dose-dependent manner.

Recurrent miscarriage and low-titer antiphospholipid antibodies.

OBJECTIVE: To evaluate the clinical features and pregnancy outcomes in patients experiencing recurrent miscarriage (RM) with either low-titer or medium-high titer positivity of antiphospholipid antibodies (aPL). METHODS: A retrospective review of medical records was conducted for patients with aPL positivity and recurrent miscarriage between 2018 and 2022. The clinical features, treatment strategies, outcomes were compared between the patients with low (n = 92) and medium (n = 32) titer of aPL. RESULTS: A total of 118 patients, resulting in 124 obstetric episodes (pregnancies), with a mean age of 33. 15 ± 4.56 and 31.47 ± 4.41 years between the two groups. The low-titer group exhibited a higher frequency of anti-cardiolipin antibodies IgM (P < 0.001), whereas the medium-high titer group demonstrated a higher frequency of anti-ß2-glycoprotein 1 antibodies IgG (P < 0.001) and IgM (P = 0.032). Moreover, the medium-high titer group displayed a significantly elevated erythrocyte sedimentation rate compared to the low-titer group (P < 0.05). In the low-titer group, 71 patients (77.2%) received appropriate treatment, resulting in 48 live births (67.6%) and 23 repeat abortions (32.4%). In the medium-high titer group, 29 patients (90.6%) received relevant treatment, leading to 23 live births (79.3%) and 6 repeat abortions (20.7%). No significant differences were observed in live births or maternal-fetal complications between the two groups (all P > 0.05). CONCLUSION: Noteworthy distinctions in laboratory parameters were identified between the low-titer and medium-high titer groups. However, when appropriately treated, the fetal-maternal outcomes were comparable in both groups. Timely intervention by clinicians is imperative to enhance pregnancy outcomes in patients experiencing recurrent miscarriage with low levels of aPL. Key Points • This study challenges the conventional belief that only the higher antiphospholipid antibodies (aPL) titers directly correlated with worse pregnancy outcomes, which emphasized the importance of patients with low titer positive aPL-positive RM. • The results underscore the need for timely intervention in women with low titer aPL-positive RM, as it leads to favorable maternal-fetal outcomes.

New advances in genomics and epigenetics in antiphospholipid syndrome.

APS patients exhibit a wide clinical heterogeneity in terms of the disease's origin and progression. This diversity can be attributed to consistent aPL profiles and other genetic and acquired risk factors. Therefore, understanding the pathophysiology of APS requires the identification of specific molecular signatures that can explain the pro-atherosclerotic, pro-thrombotic and inflammatory states observed in this autoimmune disorder. In recent years, significant progress has been made in uncovering gene profiles and understanding the intricate epigenetic mechanisms and microRNA changes that regulate their expression. These advancements have highlighted the crucial role played by these regulators in influencing various clinical aspects of APS. This review delves into the recent advancements in genomic and epigenetic approaches used to uncover the mechanisms contributing to vascular and obstetric involvement in APS. Furthermore, we discuss the implementation of novel bioinformatics tools that facilitate the investigation of these mechanisms and pave the way for personalized medicine in APS.

Epidemiology of antiphospholipid syndrome: macro- and microvascular manifestations.

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombotic and non-thrombotic macro- and microvascular manifestations and pregnancy complications in the setting of persistent antiphospholipid antibodies (aPL), namely anticardiolipin antibodies, anti-ß2 glycoprotein-I antibodies and lupus anticoagulant. Four decades after its first description, APS prevalence and incidence are still not completely understood due to the limited number of well-designed, population-based multi-ethnic studies. Furthermore, despite decades of efforts to standardise aPL immunoassays, considerable intraassay and interlaboratory variances in aPL measures still exist. Large multicentre APS cohorts have shown a 10-year survival of ∼91% and the presence of catastrophic APS occurs in about 1% of the entire population, associated with a 50% mortality rate. Clinically, any organ can be affected in the context of large, medium or small vessel (artery and/or vein) thrombosis. Macrovascular thrombosis is the hallmark of the disease and veins are more frequently affected than arteries. Deep vein thrombosis/pulmonary embolism thromboembolic disease is the most common APS manifestation, while stroke and transient ischaemic attack are the most frequent arterial thrombosis events. Myocardial infarction can also occur and contributes to increased mortality in APS. A minority of patients present with thrombosis affecting the intraabdominal organs, including the liver, spleen, small and large bowel, and the kidneys. Microvascular thrombosis, including APS nephropathy, chronic skin ulcers and livedoid vasculopathy represent a diagnostic challenge requiring histologic confirmation. In this narrative review we summarize the available evidence on APS epidemiology, focusing on the description of the prevalence of macro- and microvascular manifestations of the disease.

Phenotypes in antiphospholipid syndrome: A hierarchical cluster analysis based on two independent databases.

BACKGROUND: Antiphospholipid syndrome (APS) is a rare autoimmune disease characterized by thromboses at various sites and obstetric events associated with the persistent presence of antiphospholipid antibodies. The identification of clinical phenotypes in APS patients is a clinical need. In this study, we aimed to determine the clinical phenotypes of APS patients through an unsupervised analysis of two well-characterized cohorts of APS patients. PATIENTS AND METHODS: APS phenotypes were defined by an ascending hierarchical cluster analysis to identify preferential associations between 18 types of organ involvement and clinical characteristics. This analysis was performed on an initial multi-center cohort of 1000 patients, with validation in a replication cohort of 435 patients. RESULTS: The hierarchical analysis identified three APS phenotypes in both the initial and replication cohorts: an obstetric phenotype (n = 259 and n = 74 patients, respectively), a venous thrombosis phenotype, accounting for the largest number of patients (n = 461 and n = 297 patients, respectively), and a skin-central nervous system-heart phenotype (n = 280 and n = 64 patients, respectively). The clinical characteristics of the patients differed significantly between the three phenotypes, but there was no difference in antiphospholipid antibody profile between the groups. CONCLUSIONS: We identified three phenotypes of APS defined based on preferential associations of organ involvements and differences in presentation. These observations may help clinicians to detect organ involvement and to manage treatment.

Thrombin Generation Assay in Antiphospholipid Antibodies Positive Subjects as a Personalized Thrombotic Risk Assessment: State of the Art and Perspectives.

PURPOSE OF THE REVIEW: Thrombotic risk assessment in antiphospholipid positive (aPL +) subjects is a major challenge, and the study of in vitro thrombin generation (thrombin generation assays (TGA)) could provide useful information. Activated protein C (APC) sensitivity is involved in thrombotic events in antiphospholipid syndrome patients. We summarized methods used to assess APC sensitivity with TGA and evaluated the prognostic role of APC resistance through literature search. RECENT FINDINGS: APC resistance induced by aPL is a complex pathway. Several cross-sectional studies assessed APC sensitivity to understand thrombotic event mechanisms in aPL + subjects. Only one prospective cohort had investigated the prognostic impact of APC resistance in aPL + subjects, with a positive and significant correlation between APC sensitivity and the risk of thrombosis during the follow up (hazard ratio, 6.07 [95% CI, 1.69-21.87]). APC resistance assessed with TGA could be associated with thrombotic events in aPL + subjects.