Thrombotic Antiphospholipid Syndrome Patients Research Articles

Characteristics and prognosis of elderly-onset antiphospholipid syndrome: An observational cohort study.

Antiphospholipid syndrome (APS) is an autoimmune disease mainly affecting young individuals. Testing for antiphospholipid antibodies is recommended for young patients who are suspected to have APS. Yet, it is hard to differentiate APS from other acquired thrombophilia disorders in elderly-onset APS patients. This study aim to investigate the characteristics and prognosis of elderly-onset APS. This is an observational cohort study. Thrombotic APS patients who underwent follow-ups between 2009 and 2022 were included. Elderly-onset APS patients (onset age ≥60years) were compared to non-elderly-onset APS patients (onset age <60years) and matched cases of elderly non-APS patients (age ≥60years with thrombosis). A total of 161 APS patients were included in this study, 45 (28.0%) were elderly-onset APS. Stroke (35.6% vs. 18.1%, p = .018) was more common at disease onset in elderly-onset APS patients. Compared to non-elderly-onset patients, elderly-onset APS patients were associated with a higher number of cardiovascular risk factors. Elderly-onset APS patients showed significantly lower positive rate (51.1% vs. 71.6%, p = .014) and ratios [1.24 (1.01-1.38) vs. 1.37 (1.16-1.77), p = .004] of lupus anticoagulant. Elderly-onset APS patients had a significantly higher 10-years cumulative all-cause mortality (p < .001) and APS-related mortality than non-elderly-onset patients (p = .002) and elderly non-APS patients (p = .040). Elderly-onset APS patients have unique disease characteristics with higher 10-years cumulative all-cause mortality and APS-related mortality. Early recognition and control of comorbidities may reduce the recurrence of thrombosis and mortality in elderly-onset APS patients.

Quantification of Antiphospholipid Antibodies: The Importance of Using an Appropriate Methodology for Each Clinical Profile.

The presence of antiphospholipid antibodies (aPLs) is associated with antiphospholipid syndrome (APS), characterized by thrombosis and obstetric morbidity. aPLs included in APS classification criteria are lupus anticoagulant, anti-cardiolipin and anti-beta-2-glycoprotein-I of IgG or IgM isotypes. Enzyme-linked immunosorbent assay is the most used diagnostic technique to determine aPLs. Recently, new automated technologies mainly based in antigen-coated beads have been developed. The aim is to compare a fluorescence enzyme immunoassay (M1) and an antigen-coated bead assay (M2) in obstetric and thrombotic APS patients. All samples from the first 1020 patients received in the Immune Service Laboratory (Hospital 12 de Octubre) during the recruitment period, without exclusions, were analysed for aPLs. The weighted kappa for both methods in all the patients was 0.39 (0.30-0.47). Agreement increased to 0.56 (0.38-0.73) in patients with autoimmune disease. Sensitivity and specificity obtained for M1 were 17.1% and 89.3%, respectively, and 12.7% and 91.4% for M2. The sensibility and specificity of IgG isotypes were higher than the IgM ones. Regarding obstetric patients, M1 obtained significant diagnostic performance and had more sensitivity 23.75 (14.95-34.58) compared to M2 12.50 (6.16-21.79). In conclusion, clinical suspicion-based method selection for aPLs should be considered. To identify obstetric APS patients, solid phase methods remain more preferable.

Prevalence, Domain Specificity, and Residue Specificity of IgG, IgM, and IgA Anti-β2GPI Antibodies in Tetra-Positive Antiphospholipid Syndrome Patients: Identification of Two Non-Overlapping Epitopes in Domain I of β2GPI

Background. Risk stratification of antiphospholipid syndrome (APS) patients involves several laboratory tests, including lupus anticoagulant (LAC), anti-cardiolipin antibodies (anti-CL), anti-β2GPI antibodies (anti-β2GPI), and, more recently, anti-phosphatidylserine/prothrombin antibodies (anti-PS/PT). Patients with positive results for all four tests, known as tetra-positive APS patients, are considered at high risk for thrombotic recurrence. β2GPI is a protein composed of five domains: DI, DII, DIII, DIV, and DV, arranged in a flexible elongated structure. Previous studies have demonstrated that DI is frequently targeted by IgG in thrombotic APS patients. However, the prevalence, domain specificity, and residue specificity of the three different isotypes of anti-β2GPI antibodies in tetra-positive APS patients remain unknown. Objective. To establish the prevalence, domain specificity, and residue specificity of IgG, IgM, and IgA anti-β2GPI antibodies in tetra-positive APS patients. Methods. Plasma samples from 32 clinically confirmed tetra-positive APS patients and 8 healthy controls were analyzed for levels of IgG, IgM, and IgA using an enzyme-linked immunosorbent assay (ELISA) with immobilized β2GPI as the antigen. Domain and residue mapping were investigated using five deleted domain variants and eight single-point mutations. Mutants lacking specific disulfide bonds were used to assess whether the epitopes targeted by the antibodies are linear or conformational. Results. Among the 32 patients tested, 31 (96%) had IgG, 18 (56%) had IgM, and 18 (56%) had IgA anti-β2GPI antibodies. Ten patients (31%) had all three isotypes, 7 (22%) had IgG and IgM, and 8 (25%) had IgG and IgA. Six patients (19%) had only IgG, 1 had only IgM, and none had only IgA. The removal of DI from the β2GPI molecule led to an almost complete loss of binding (~80%) for the majority of IgG antibodies. There was a lesser but still significant reduction in binding when DII and DV were removed. However, no loss of binding was observed with variants lacking DIII and DIV. Notably, IgA antibodies behaved similarly to IgG but differently from IgM, as their reactivity towards DI and DV was significantly attenuated. To investigate the contribution of specific residues to binding, charged residues K19, E23, E26, E27, R39, R43, K44, and K59 in DI were individually replaced with alanine (A). The most important residue for IgG and IgA antibodies was R43, followed by R39 and K44. In contrast, most residues contributed to optimal binding for IgM antibodies, suggesting a less specific epitope definition. Interestingly, the mutations R39A and K44A often led to loss of binding in conjunction with the mutation R43A, but rarely simultaneously, suggesting the existence of two distinct epitopes for anti-DI antibodies-one located north and one south of R43. Finally, IgG, IgM, and IgA antibodies did not react against the mutant C32S/C60S but showed good reactivity against the mutant C288S/C326S, indicating that epitopes in DI are conformational and require the integrity of the disulfide bond 32-60. Conclusions. In tetra-positive APS patients, IgG anti-β2GPI antibodies are the most prevalent isotype, followed by IgA and IgM. The IgG and IgA isotypes exhibit a pronounced preference for DI, while the IgM isotype demonstrates lower specificity, which aligns with IgM's role as initial responders in infections. Notably, our research revealed that anti-DI antibodies are diverse, as they recognize epitopes within DI that are closely related but physically distinct. Ongoing studies aim to further characterize these antibody subtypes and understand their significance in APS. This knowledge may inform improved diagnostic and therapeutic approaches for APS patients.

Complement Activation Is Increased in Antiphospholipid Syndrome-Related Ischemic Stroke with Higher Risk Features

Introduction: Antiphospholipid syndrome (APS) patients with arterial thrombosis, mostly ischemic stroke, have concerningly high rates of recurrent thrombosis despite antithrombotic treatment, with over 20% thrombosis recurrence within two years. Complement activation is increased in thrombotic APS patients, although its role has not been fully investigated in APS-related stroke. This study aimed to evaluate the degree of complement activation in APS-related ischemic stroke, transient ischemic attack (TIA) or other ischemic brain injury patients and whether complement activation correlated with APS severity and platelet hyperreactivity as a potential mechanism for increased thrombotic risk. Method: Patients with confirmed APS by Sydney Criteria and imaging-proven ischemic stroke, TIA or other ischemic brain injury were recruited, subcategorized as high-risk APS (HR-APS, n=30) and lower-risk APS (LR-APS, n=41). HR-APS included triple antiphospholipid antibody (aPL) positive, anticoagulant refractory or both arterial and venous thromboembolism patients. LR-APS included patients with a single thrombotic event who were single or double aPL positive. Ischemic stroke patients without aPL (n=40) and healthy donors (n=40) were utilized as controls. Patients with active cancer, inflammation, infection or use of hydroxychloroquine, immunosuppression and heparins were excluded. Complement activation markers were measured as Bb fragment (Bb), C3a-desArg (C3a), C5a-des-Arg (C5a), and SC5b-9 using ELISA (MicroVue kits, Quidel Corp, Pathway Diagnostics Ltd). Complement-mediated cell killing was measured by the modified Ham (mHam) test, which determines the degree of cell lysis after adding patient serum to a paroxysmal nocturnal hemoglobinuria cell line (PIGA-null TF-1 cells) lacking cell surface complement regulators. A positive result was considered 20% or greater cell killing. Flow cytometry was used to evaluate whether complement activation correlated with platelet hyperreactivity. For this, plasma from mHam positive patients was added to healthy donor whole blood and procoagulant platelet response was measured as the absolute change in proportion of platelet events that were positive for annexin V and P-selectin following stimulation with thrombin 2U/mL. Results: There was no significant difference in median age between the patient cohorts, ranging from 49 to 56 years, although the healthy controls were younger, with median age 36 (range 25-73, p&amp;lt;0.001). Circulating complement activation markers were all significantly increased in the APS cohorts compared to healthy controls (p&amp;lt;0.01). The most prominent increase was observed in C3a levels: HR-APS median (interquartile range - IQR) 215 ng/mL (137.1-297.4), LR-APS 290.8 ng/mL (120.3-450.3) and healthy controls 62 ng/mL (27.9-121.1)(p=0.004 and p&amp;lt;0.0001 compared to healthy controls, respectively); and Bb fragment levels: HR-APS 1.2 µg/mL (IQR 1.0-1.4), LR-APS 1.3 µg/mL (IQR 1.0-1.5) and healthy controls 0.8 µg/mL (IQR 0.7-0.9)(both p&amp;lt;0.0001 compared to healthy controls). However, only C3a, SC5b-9 and Bb fragment levels in LR-APS remained significantly elevated when compared to stroke controls (p=0.0009, p=0.01 and p=0.03, respectively). There were no differences between HR-APS and LR-APS, nor between stroke controls and healthy controls. Complement-mediated cell killing was also significantly higher in APS patients overall, median (IQR) proportion of non-viable cells 18% (IQR 12-33), compared to stroke controls: 10% (IQR 8-15, p&amp;lt;0.0001) and healthy controls: 12.5% (IQR 6.3-17, p=0.0009). Notably, HR-APS had significantly higher proportion of positive mHam tests (60%), compared to LR-APS: 36.6%, stroke controls: 12.5%, and healthy controls: 17.5% (p&amp;lt;0.0001, Figure 1A). Importantly, HR-APS patients with positive mHam results (n=5) induced a substantially higher increase in procoagulant platelets, median 17.2% (IQR 11.2-28.6), whereas healthy controls (n=4) only resulted in median change of -0.7% (IQR -7.0-1.4, p=0.02) (Figure 1B). Conclusion: Preliminary data suggest that APS-related ischemic stroke, TIA or ischemic brain injury are associated with increased, functionally important, complement activation, more prominent in higher risk disease. Complement-mediated platelet hyperreactivity may have a contributory role that remains to be established.

Abstract 18 — Standardized Mortality Ratio and Risk Factors for Mortality and Recurrence in Hong Kong Chinese Patients with Antiphospholipid Syndrome

Background To report standardized mortality ratio (SMR) and assess risk factors for mortality and recurrence in Hong Kong Chinese patients with antiphospholipid syndrome (APS). Methods Patients followed up in 16 public hospitals in Hong Kong were identified by the Hospital Authority Clinical Data Retrieval System (CDARS) using the ICD-10 diagnostic code of APS. Their diagnoses were verified using the 2006 modified consensus criteria (1) for APS. The mortality, thrombosis recurrence rate and their associated risk factors were studied by Kaplan-Meier method and Cox Regression. Results Four hundred twenty-three Chinses APS patients were identified. Among them, 288 patients fulfilled the 2006 criteria for APS and were classified as definite APS, while 135 patients had probable APS. APS was primary in 204 patients and secondary in 219 patients. On presentation, 369 patients had thrombotic events. Arterial thrombosis occurred in 177 patients and venous thrombosis occurred in 189 patients. Obstetric morbidities occurred in 77 patients. Twenty three patients had both obstetric and thrombotic events. Over a mean follow-up of 9.7±7.2 years, 75 (17.7%) patients succumbed. The age and sex adjusted SMR relative to general population was 4.34[95% CI 3.44-5.41]. In thrombotic APS patients, mortality was associated with age [Formula: see text]60 years at diagnosis (HR 5.30 [95% CI 3.11-9.03]; p&lt;0.001), presence of arterial hypertension (HR 1.89 [95% CI 1.11-3.19]; p =0.018), and presence of arterial thrombosis (HR 1.81 [95% CI 1.06-3.10]; p=0.031). Recurrence of thrombosis occurred in 89 (21%) patients (15% arterial, 5.2% venous). Recurrence of thrombosis was found to be associated with triple positive antibodies (HR 2.71 [95% CI 1.15-6.42]; p=0.023) independent of other risk factors in a multivariate model. Conclusion Increased mortality rate was observed in Chinese APS patient, with older age at diagnosis, presence of arterial hypertension and arterial thrombosis being independent risk factors for mortality. Recurrence of thrombotic events was not uncommon and associated with the presence of triple positive aPL antibodies.

PB0757 Comparison of Clinical and Serological Features in Thrombotic Antiphospholipid Syndrome Patients, with and without Associated SLE, Followed for up to 42 Years: A Single Centre Retrospective Study

PB0757 Comparison of Clinical and Serological Features in Thrombotic Antiphospholipid Syndrome Patients, with and without Associated SLE, Followed for up to 42 Years: A Single Centre Retrospective Study

Small-Extracellular-Vesicle-Derived miRNA Profile Identifies miR-483-3p and miR-326 as Regulators in the Pathogenesis of Antiphospholipid Syndrome (APS).

Primary antiphospholipid syndrome (PAPS) is a systemic autoimmune disease associated with recurrent thrombosis and/or obstetric morbidity with persistent antiphospholipid antibodies (aPL). Although these antibodies drive endothelial injury and thrombophilia, the underlying molecular mechanism is still unclear. Small extracellular vesicles (sEVs) contain miRNAs, key players in intercellular communication. To date, the effects of miRNA-derived sEVs in PAPS are not well understood. We characterised the quantity, cellular origin and miRNA profile of sEVs isolated from thrombotic APS patients (PAPS, n = 50), aPL-carrier patients (aPL, n = 30) and healthy donors (HD, n = 30). We found higher circulating sEVs mainly of activated platelet origin in PAPS and aPL patients compared to HD, that were highly engulfed by HUVECs and monocyte. Through miRNA-sequencing analysis, we identified miR-483-3p to be differentially upregulated in sEVs from patients with PAPS and aPL, and miR-326 to be downregulated only in PAPS sEVs. In vitro studies showed that miR-483-3p overexpression in endothelial cells induced an upregulation of the PI3K-AKT pathway that led to endothelial proliferation/dysfunction. MiR-326 downregulation induced NOTCH pathway activation in monocytes with the upregulation of NFKB1, tissue factor and cytokine production. These results provide evidence that miRNA-derived sEVs contribute to APS pathogenesis by producing endothelial cell proliferation, monocyte activation and adhesion/procoagulant factors.

Neural Network Diagnoses the Antiphospholipid Syndrome without Interrupting Anticoagulant Therapy

Background The antiphospholipid syndrome (APS) is characterized by the presence of antiphospholipid antibodies (aPL) and is associated with an increased risk of thrombosis and pregnancy morbidity. The Laboratory diagnosis of APS is difficult because most patients already use anticoagulants due to a thrombotic event, resulting in interference with the clotting assays used for lupus anticoagulant (LAC) testing. Nevertheless, the aPL profile defines patient management, making aPL testing warranted during anticoagulant therapy. Sometimes, cessation of anticoagulant treatment is necessary to perform the lupus anticoagulant (LAC) test, which is unfavorable. The thrombin generation (TG) test is a functional and global hemostatic test. Clinical studies have shown that increased TG is associated with thrombosis, also in thrombotic APS patients. We have previously shown that the artificial intelligence method neural networks can be used to diagnose untreated APS patients from a group of healthy, auto-immune disease, and thrombosis controls with high accuracy. At the moment of aPL testing, many patients are already on anticoagulants, hampering the detection of LAC. Therefore, we developed a neural net (NN) for diagnoses APS in a cohort of anticoagulated subjects, based on the TG test. Methods Antiphospholipid antibodies positivity was diagnosed according to the Sapporo-Sydney guidelines. TG was measured using the calibrated automated thrombogram assay (CAT) on platelet poor plasma with PPP reagent (intermediate concentration of tissue factor) in 48 APS patients and 64 control non-APS patients, both treated with vitamin K antagonists (VKAs) TG was explored in more depth by quantifying parameters of prothrombin conversion and thrombin inactivation, using thrombin dynamics (TD) analysis, and assessing the sensitivity of the activated protein C pathway through the addition of thrombomodulin (TM). Five NNs were developed and the most accurate NN was selected for clinical validation based on its sensitivity and specificity. Input parameters for the NN were TG parameters lag time, peak, endogenous thrombin potential, time-to-peak, and velocity index, and TD parameters total prothrombin conversion, maximum prothrombin conversion rate, thrombin-antithrombin complex formation, and thrombin-α2-macroglobulin complex formation, and the inhibition of TG and TD by TM. The top performing NN was clinically validated using the TG and TD data acquired in the validation cohort, consisting of 33 APS patients and 62 controls, both on VKA therapy, 49 auto-immune disease controls, 38 thrombosis controls, 92 patients visiting the hospital for other indications and 37 healthy subjects. All control subjects were negative for aPL. Results TG was slightly increased in APS patients compared to controls. VKA therapy abolished the typical lag time prolongation seen in non-anticoagulated APS patients due to the LAC effect. The rate of prothrombin conversion was significantly increased in anticoagulated APS patients compared to controls, indicating a more prothrombotic phenotype. The selected NN classified APS patients with a sensitivity of 92% and a specificity of 95% in the developmental cohort consisting of APS patients and controls on VKA antagonists (ROCAUC = 0.9805; 0.9542-1.000; p<0.0001). On average, controls and APS patients were assigned an APS likelihood score of 12% and 89%, respectively. The NN was clinically validated in a separate validation cohort of 311 individuals, including 33 anticoagulated APS patients, 62 anticoagulated controls, 38 thrombosis patients, 49 auto-immune disease patients, 92 hospital controls, and 37 healthy controls. The sensitivity of the NN for the detection of APS was 85%. The overall specificity of the NN was 93%, and 100%, 96%, 96%, 92% and 76% respectively in healthy controls, auto-immune disease controls, hospital controls, anticoagulated controls, and thrombosis controls. Conclusions We developed a NN that accurately classifies APS under anticoagulant treatment. Therefore, this NN could be an alternative for diagnosing APS patients already treated with VKAs. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Asymmetric Dimethylarginine Is a Marker of Endothelial Dysfunction in Thrombotic Antiphospholipid Syndrome Patients.

Objective: The potential contribution of asymmetric dimethylarginine (ADMA) and high-sensitivity C reactive protein (hsCRP) to endothelial dysfunction in APS patients has not been studied in detail, until now. The study involved 105 APS patients (59 diagnosed with primary APS (PAPS) and 46 APS associated with systemic lupus erythematosus (SAPS)) who were compared to 40 controls. Endothelial dysfunction was assessed by measurement of flow-mediated dilatation (FMD) and glyceryl trinitrate dilatation (NMD) of the brachial artery. ADMA (micromol/L) was analyzed by ELISA. Results: FMD in patients with APS was significantly lower than that of the controls (p < 0.001), with no difference between the PAPS and the SAPS groups. ADMA and hsCRP concentrations were significantly higher in the patient cohort than in the control group (p < 0.001, p = 0.006, respectively), as was the case with the SAPS group as compared to the PAPS group (p < 0.001, p = 0.022, respectively). FMD impairment correlated to ADMA (ρ 0.472, p < 0.001) and to hsCRP (ρ 0.181, p = 0.033). In the regression model, the ADMA concentration confirmed the strength of its association (B 0.518, SE 0.183, Wald 8.041, p = 0.005, Exp(B) 1.679, 95% CI 1.174–2.402) to FMD impairment. The synergistic probability model of ADMA and hsCRP caused FMD impairment when the positivity of β2GPIIgG was added. ADMA may be used as a simple and low-cost tool for verifying the presence of endothelial dysfunction in APS patients. According to the results of the study, we could presume that hsCRP, together with aPL, has a preparatory effect on the endothelium in causing endothelial dysfunction.

Influencing factors of thrombosis besides antiphospholipid antibodies in patients with antiphospholipid syndrome

Objective: To identify the influencing factors of thrombosis besides antiphospholipid antibodies in patients with antiphospholipid syndrome (APS). Methods: The 169 patients diagnosed with APS were enrolled according to the current APS classification criteria from January 2003 to August 2017 in Peking University People's Hospital. There were 23 males and 146 females with a mean age of (41±15) years. Antiphospholipid antibodies, including anticardiolipin (aCL), anti-β2glycoprotein-1 (β2GP1) antibodies and antibodies to the phosphatidylserine-prothrombin complex (aPS/PT), were determined by enzyme-linked immunosorbent assay (ELISA) methods. Lupus anticoagulant (LA) was identified using the STA Compact coagulation testing system. The differences of clinical and laboratory characteristics between patients with and without thrombosis were analyzed (100 cases and 69 cases, respectively). The influencing factors for thrombosis in patients with APS were determined using binary logistic regression. Results: Compared with patients without thrombosis, patients with thrombosis were older and had a longer disease duration ((45±17) years vs (35±9) years and M(Q1, Q3) 12.0(3.8, 84.0) months vs 48.0(12.0, 108.0) months, both P<0.05). The percentage of male, primary APS, smoking, low blood platelet count, hypertension, and diabetes in patients with thrombosis were significantly higher than those in patients without thrombosis (all P<0.05). Similarly, the rates of antinuclear antibodies positive, aCL positive, aPS/PT-IgM positive, and aPS/PT-IgG positive in patients with thrombosis were significantly higher than those in patients without thrombosis (all P<0.05). The levels of D-dimer in patients with thrombosis were significantly higher than that in patients without thrombosis (P<0.05). There was significant difference in global anti-phospholipid syndrome score (GAPSS) between patients with and without thrombosis (P<0.05). The GAPSS score was also significantly higher in patients with arterial thrombosis than that in patients with venous thrombosis (P<0.05). Smoking and D-dimer levels were independent influencing factors for thrombosis in patients with APS (smoking: OR=11.222, 95%CI:1.119-112.544, P=0.040, D-dimer levels: OR=1.002, 95%CI: 1.000-1.003, P=0.037). Conclusions: Thrombotic APS patients are older and have a longer suffering duration, a higher ratio of male, primary APS, smoking, hypertension, lower blood platelet count, diabetes, higher GAPSS scale, and higher D-dimer levels. Smoking and D-Dimer levels may be independent risk factors for thrombosis in patients with APS.

Insight into the hypercoagulable state of high‐risk thrombotic APS patients: Contribution of aβ2GPI and aPS/PT antibodies

ObjectiveMost high‐risk thrombotic antiphospholipid syndrome (APS) patients test positive for anti‐β2‐glycoprotein I (aβ2GPI) and anti‐phosphatidylserine/prothrombin (aPS/PT) antibodies. Information on the influence of these antibodies on thrombin generation and activated protein C resistance (aPCr) is still sparse and contradictory. MethodsPlasma of 16 patients poured into a β2GPI affinity column allowed the perfect separation of aβ2GPI and aPS/PT antibodies. aPS/PT antibodies were further purified through a prothrombin affinity column. Obtained material was spiked into normal pooled plasma (NPP) and tested in the thrombin generation assay in the absence or presence of aPC. ResultsaPS/PT antibodies showed a marked anticoagulant effect. Affinity purified aPS/PT and aβ2GPI antibodies from five patients were compared. aPS/PT antibodies showed significantly prolonged lag time and time to peak (5.0 minutes [interquartile range (IQR)3.5–6.1] versus 2.7 minutes [IQR2.2–3.5], P = .03 and 8.7 minutes [IQR6.7–10.3] versus 5.7 minutes [IQR4.5–6.2], P = .05, respectively) and significantly lower peak and velocity index (143 nmol/L [IQR131–163] versus 171 nmol/L [IQR157–182], P = .03 and 35 nmol/L/min [IQR32–59] versus 72 nmol/L/min [IQR54–77], P = .03, respectively). When aPC was added to the system, aPCr was significantly increased compared to controls for both aβ2GPI and aPS/PT antibodies. However, it was significantly stronger using aPS/PT antibodies. Median inhibition of endogenous thrombin potential was 22% (IQR16–33) with aPS/PT compared to 52% (IQR46–56) with aβ2GPI antibodies (P = .002). ConclusionsAβ2GPI antibodies show a mild anticoagulant and moderate procoagulant effect in thrombin generation and moderate aPC resistance. Conversely, aPS/PT antibodies show a strong anticoagulant effect and a strong aPCr.

Comparison of the Therapeutic Effects of Rivaroxaban Versus Warfarin in Antiphospholipid Syndrome: A Systematic Review.

This study aims to review the studies evaluating the therapeutic effects of rivaroxaban versus those of warfarin in patients with antiphospholipid syndrome (APS). The study included randomized clinical trials, comparative studies, cross-sectional investigations, and case series that focused on the effects of warfarin and rivaroxaban and compared the effects of these anticoagulants in patients with APS. The relevant articles published until 2018 were searched in several databases, including PubMed, Scopus, ScienceDirect, Google Scholar, Embase, and Web of Science. The findings of the reviewed studies showed that rivaroxaban can be used as an effective and safe alternative to warfarin in APS patients. However, the effectiveness of rivaroxaban in the prevention of thrombosis in high-risk APS patients is suspected. Given the high risk of using rivaroxaban in thrombotic APS patients with labile international normalized ratio (INR) or poor adherence to INR monitoring, it is not suggested to use this agent for these patients.

IgG Anti-high-Density Lipoproteins Antibodies Discriminate Between Arterial and Venous Events in Thrombotic Antiphospholipid Syndrome Patients.

Introduction: Recurrent thrombotic events are a hallmark of Antiphospholipid Syndrome (APS). However, biomarkers to identify if a patient with antiphospholipid antibodies (aPL) is at higher risk to develop an arterial or a venous event are lacking. Recently, the pathogenic role of anti-high-density lipoproteins antibodies (anti-HDL) in the occurrence of cardiovascular disease (CVD) in autoimmunity has emerged. The aim of the present study was to evaluate the presence of IgG anti-HDL antibodies in a cohort of thrombotic APS patients and to investigate their association with clinical outcomes.Methods: Serum levels of IgG anti-HDL antibodies, total IgG, and complete aPL profile were assessed in 60 APS patients and 80 healthy donors (HDs) by immunoassays.Results: Higher levels of IgG anti-HDL were found in APS patients compared to HDs (p < 0.001), even after correcting for total IgG levels (p < 0.001). No associations with treatments or traditional cardiovascular risk factors, except for smoking habit (p < 0.0001), were found. Patients who experienced at least one arterial event (n = 30) had significantly higher levels of anti-HDL antibodies when compared to patients with venous thrombosis (n = 30, p = 0.046), this difference being stronger when adjusting for total IgG (p = 0.007). Additionally, patients tested positive for antiphosphatidylserine/prothrombin (IgG/IgM) antibodies had significantly higher levels of anti-HDL antibodies (p = 0.045).Conclusions: Increased levels of IgG anti-HDL antibodies can be found in APS, mainly in patients with arterial thrombosis, independently of aPL antibodies and traditional risk factors. These findings point to a role of anti-HDL antibodies in APS and support their use as a potential biomarker for arterial thrombotic events.

Identification of high thrombotic risk triple‐positive antiphospholipid syndrome patients is dependent on anti‐cardiolipin and anti‐β2glycoprotein I antibody detection assays

Background The antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with the persistent presence of antiphospholipid antibodies (aPL). Triple-positivity (i.e. positivity for lupus anticoagulant [LAC], anti-cardiolipin [aCL] and anti-β2glycoprotein I [aβ2GPI] antibodies) is associated with a high thrombotic risk. Objectives We investigated the variability in triple-positivity detection by measuring the same samples with four commercially available solid phase assays. In addition, the added clinical value of aPL in LAC-positive patients was investigated, as well as the association of IgM triple-positivity and thrombosis. Patients/Methods We included 851 patients from seven European medical centers. Anti-CL and aβ2GPI IgG/IgM antibodies were determined by four platforms: BioPlex® 2200, ImmunoCap® EliA, ACL AcuStar® and QUANTA Lite ELISA® . Results Triple-positivity detection by solid phase assays varied, ranging from 89 up to 118 in thrombotic APS patients (n = 258), of which 86 were detected independent of the platform. Lupus anticoagulant positivity resulted in an odds ratio (OR) for thrombosis of 3.4; triple-positivity (irrespective of the isotype) increased the OR from 4.3 up to 5.2, dependent on the platform. Triple-positivity solely for the IgM isotype did not increase the OR for thrombosis compared with LAC positivity. The highest OR for thrombosis was reached for positivity for IgG and IgM aβ2GPI and aCL (8.6 up to 28.9). Conclusions Triple-positivity proved to be highly associated with thrombosis, but identification is assay dependent. Within triple-positivity, IgM antibodies only have an added clinical value in patients positive for IgG antibodies.

Thrombin generation and factor X assays for the assessment of warfarin anticoagulation in thrombotic antiphospholipid syndrome

Monitoring warfarin anticoagulation in patients with thrombotic antiphospholipid syndrome (APS) may be complicated by the sensitivity of different thromboplastins to lupus anticoagulant. The aim of this study was to compare the degree of anticoagulation intensity in thrombotic APS and non-APS patients (50 in each group) on long-term warfarin, by measurement of the INR with two widely available thromboplastins with instrument-specific ISI values, and to investigate the potential role of amidolytic FX levels and thrombin generation (TG) testing in the assessment of anticoagulant intensity in thrombotic APS patients. There were no overall differences in INR between reagents or patient groups, but 20% (10/50) of APS patients showed ≥0.5 INR unit difference between reagents, which would have resulted in altered clinical management in some patients. FX levels were useful in assessing anticoagulation intensity for INR 2.0-3.0, but showed poor utility at INR ≥3.5 where the lowest measured FX level was 12IU/dL. In contrast, ETP and peak thrombin showed significant inverse correlations with the INR, suggesting that TG testing may be helpful in the determination of true anticoagulant intensity in APS patients, including those with ≥3.5 INR. TG testing also highlighted a subgroup of APS patients with increased peak thrombin relative to the intensity of anticoagulation as assessed by INR and FX, suggesting that TG testing may be useful in identifying an ongoing prothrombotic state in patients with apparently adequate anticoagulation intensity as assessed by INR.

In APS, two A1’s are better than one!

In this issue of Blood, Kolyada and colleagues elegantly demonstrate the therapeutic utility of a novel, synthetically constructed molecule, the A1 dimer (A1-A1), in preventing anti-β2 glycoprotein I (anti-β2GPI) autoantibody-mediated thrombosis in 2 distinct murine antiphospholipid syndrome (APS) thrombosis models. Current therapies for thrombotic APS entail long-term anticoagulation, with the associated risk of bleeding complications. The findings presented by Kolyada et al raise the possibility of perhaps using this agent to treat thrombotic APS patients in the future, allowing for a reduction in bleeding risk.1

CD8+DR+ T-Cells and C3 Complement Serum Concentration as Potential Biomarkers in Thrombotic Antiphospholipid Syndrome

Purpose. To assess complement factors and T lymphocyte activation subset abnormalities in patients with thrombotic antiphospholipid syndrome (APS) as potential biomarkers for development of clinical complications. Methods. We assessed C3, C4, factor B concentrations (nephelometry), complement haemolytic functional activity (CH100, radial immune diffusion), and the activation status of CD4+ and CD8+ T-cells (three-colour flow cytometry) in patients with thrombotic APS. Antiphospholipid (aPL) positive patients without APS-related clinical criteria, systemic lupus erythematosus (SLE) patients, and healthy individuals were evaluated as controls. A clinical followup was performed to assess the potential relationship between the immunological parameters and development of APS-related complications. Results. Lower concentrations of C3 and higher levels of CD8+DR+ cells were risk factors for development of APS-related complications during followup, including rethrombosis and neuropsychiatric symptoms. Patients with diagnosed thrombotic APS had significantly lower levels of C3, C4, and CH100 as well as higher percentages of activated CD4+DR+ and of CD8+DR+ T-cells than healthy controls but similar to that observed in autoimmune disease controls. Conclusion. Lower C3 and C4 complement levels and higher percentages of CD8+DR+ T-cells were observed in thrombotic APS patients. The potential role of these abnormalities as biomarkers of clinical outcome warrants further evaluation in a multicenter study.

Risk-based secondary prevention of obstetric antiphospholipid syndrome

Treatment of pregnant women with antiphospholipid syndrome (APS) should be set apart from that from thrombotic APS patients. Patients with a history of pregnancy morbidity but no vascular thrombosis are usually treated with a prophylactic dose of heparin plus low-dose aspirin; whereas, those with previous vascular thrombosis alone or associated with previous pregnancy morbidity, are commonly treated with a therapeutic dose of heparin generally combined with low-dose aspirin. However, in about 20% of pregnant APS women these regimens fail. In this context, we conducted a case-control study on a large multicentre cohort of conventionally treated pregnancies to verify whether specific laboratory profiles and/or clinical characteristics are predictive of unsuccessful pregnancy outcome during conventional treatments. Multivariate analysis showed that pregnancy failure during conventional therapies was independently associated with a history of both thrombosis and pregnancy morbidity, the presence of systemic lupus erythematosus (SLE) or other systemic autoimmune diseases and triple antiphospholipid antibody positivity. With the aim to discover the most effective and safe treatments in high-risk pregnant APS women a large-scale multicentre study focusing on the effect of treatments on pregnancy outcome in women with APS and further risk factors for pregnancy failure has been designed.

Studies of microparticles in patients with the antiphospholipid syndrome (APS)

To study circulating platelet, monocyte and endothelial microparticles (PMPs, MMPs and EMPs) in patients with antiphospholipid syndrome (APS) in comparison with healthy controls. Fifty-two patients with APS and 52 healthy controls were investigated. MPs were measured on a flow cytometer (Beckman Gallios) and defined as particles sized < 1.0 µm, negative to phalloidin, positive to lactadherin and positive to either CD42a (PMPs), CD144 (EMPs) or CD14 (MMPs). Exposure of CD142 (TF) was measured on CD144 positive MPs. Total number of MPs (i.e. lactadherin positive particles) was higher in APS patients versus controls (p < 0.001). An increased number of EMPs (p < 0.001), increased TF-positive EMPs (p < 0.001) and increased MMPs (p < 0.001) were also observed. PMP numbers did not differ between the groups. None of the MP types differed in numbers between obstetric and thrombotic APS patients. We observed a high number of EMPs expressing TF in APS patients. The numbers of MMPs and total EMPs were also higher as compared with healthy controls but in contrast to previous reports, the number of PMPs did not differ between groups.