Anti-β2 GPI Research Articles

Perinatal outcomes in indian women with Antiphospholipid Antibody Syndrome (APS): Five year experience from a tertiary care centre

BackgroundAntiphospholipid Syndrome (APS) is a systemic autoimmune thrombophilic condition characterized by obstetric manifestations, including pregnancy loss, preeclampsia and fetal growth restriction. Early diagnosis and management are key to improve maternal and neonatal outcomes. ObjectiveThe aim of this study is to assess the perinatal outcomes in APS, the development of various adverse pregnancy outcomes (APO), and their association with specific antibody profiles. Material methodsThis observational study was carried out on booked cases of singleton pregnancy and diagnosed cases of primary APS in our High-Risk Pregnancy (HRP) clinic from January 2018 to December 2022 after approval from institutional ethics committee. Forty-three confirmed cases of primary APS were enrolled and started on low-dose aspirin and low-molecular-weight heparin (LMWH) as per the patient's body weight after confirmation of fetal heart activity radiologically until 36 weeks of gestation as a standard of care. ResultsForty patients (93 %) had obstetric APS, and three patients (7 %) had thrombotic APS. During the course of the current pregnancy, adverse pregnancy outcomes (APO) developed in 12 (30 %) out of 40 cases of obstetric APS and in all 3 patients with thrombotic APS. Preeclampsia was seen in 11 (25.5 %), FGR in 12 (27.9 %), and preterm birth in 7 (16.2 %) cases. Patients with an antibody profile showing the presence of Anti-β2 GP-I positivity and ACL positivity had fewer APOs (20 % and 29 %) in comparison to patients with a LA and triple positive antibody profile (55 % and 50 %). ConclusionTreatment of pregnant women with APS causes significant improvement in the live birth rate. The late pregnancy complications like preeclampsia, FGR, and premature birth, occurring despite treatment still remains a challenge and emphasizes the need for stringent antepartum surveillance and timely delivery.

The association between antiphospholipid syndrome and atrial fibrillation: a single center retrospective case-control study.

Antiphospholipid syndrome (APS) is a systemic autoimmune syndrome characterized by arterial or venous thrombosis, pregnancy complications and thrombocytopenia. The aim of this study is to investigate the association between APS and atrial fibrillation (AF) among patients in Peking University People's Hospital. A single center retrospective study was conducted. Cases were hospitalized patients diagnosed with AF by a cardiologist while the control group patients did not exhibit cardiac diseases. The results of the study revealed that in multivariable logistic regression, APS, anticardiolipin antibody (aCL) positivity and anti-beta-2-glycoprotein antibody (anti-β2GPI) positivity are independent risk factors of AF. APS, aCL positivity and anti-β 2GPI positivity are statistically different between AF patients and non-AF patients. Forthcoming studies are needed to clarify the potential link between APS and AF.

Mild-to-moderate COVID-19 does not predispose to the development of autoimmune rheumatic diseases or autoimmune-based thrombosis.

An infection with severe acute respiratory syndrome coronavirus (SARS-CoV-2) may have a significant impact on the human immune system. Interactions between the virus and defence mechanisms may promote the development of autoimmune processes which manifest as antinuclear antibody (ANA) synthesis. Since many different viruses are suspected to take part in the pathogenesis of different systemic autoimmune rheumatic diseases (SARDs), we examined whether coronavirus disease 2019 convalescents who suffer from mild to moderate disease have a higher risk of developing ANA and anti-β2-glicoprotein I IgG antibodies (β2 GPI). In a retrospective study, we examined 294 adults among volunteer blood donors divided into convalescents (N = 215) and healthy controls (N = 79). For ANA detection, we used line-blotting, a type of indirect immunofluorescence assay (IF), to determine antigenic specificity and ELISA for β2 GPI. We found a lower incidence of ANA in convalescents than in healthy controls, with the majority of these antibodies directed to antigens with no known clinical significance. Additionally, no participants were positive for β2 GPI in either group. Our results show that COVID-19 with mild to moderate symptoms in the generally healthy population does not induce the development of ANA or anti-β2 GPI antibodies for at least 6 months following the disease.

Fluctuation of Anti-Domain 1 and Anti-β2 -Glycoprotein I Antibody Titers Over Time in Patients With Persistently Positive Antiphospholipid Antibodies.

The present study was undertaken to longitudinally evaluate titers of antibodies against β2 -glycoprotein I (anti-β2 GPI) and domain 1 (anti-D1), to identify predictors of variations in anti-β2 GPI and anti-D1 titers, and to clarify whether antibody titer fluctuations predict thrombosis in a large international cohort of patients who were persistently positive for antiphospholipid antibodies (aPL) in the APS ACTION Registry. Patients with available blood samples from at least 4 time points (at baseline [year 1] and at years 2-4 of follow-up) were included. Detection of anti-β2 GPI and anti-D1 IgG antibodies was performed using chemiluminescence (BIO-FLASH; INOVA Diagnostics). Among 230 patients in the study cohort, anti-D1 and anti-β2 GPI titers decreased significantly over time (P < 0.0001 and P=0.010, respectively). After adjustment for age, sex, and number of positive aPL tests, we found that the fluctuations in anti-D1 and anti-β2 GPI titer levels were associated with treatment with hydroxychloroquine (HCQ) at each time point. Treatment with HCQ, but not immunosuppressive agents, was associated with 1.3-fold and 1.4-fold decreases in anti-D1 and anti-β2 GPI titers, respectively. Incident vascular events were associated with 1.9-fold and 2.1-fold increases in anti-D1 and anti-β2 GPI titers, respectively. Anti-D1 and anti-β2 GPI titers at the time of thrombosis were lower compared to titers at other time points. A 1.6-fold decrease in anti-D1 titers and a 2-fold decrease in anti-β2 GPI titers conferred odds ratios for incident thrombosis of 6.0 (95% confidence interval [95% CI] 0.62-59.3) and 9.4 (95% CI 1.1-80.2), respectively. Treatment with HCQ and incident vascular events in aPL-positive patients predicted significant anti-D1 and anti-β2 GPI titer fluctuations over time. Both anti-D1 and anti-β2 GPI titers decreased around the time of thrombosis, with potential clinical relevance.

Characteristics of Patients With Antiphospholipid Antibody Positivity in the APS ACTION International Clinical Database and Repository.

To describe the baseline characteristics of patients with positivity for antiphospholipid antibodies (aPLs) who were enrolled in an international registry, the Antiphospholipid Syndrome (APS) Alliance for Clinical Trials and International Networking (APS ACTION) clinical database and repository, overall and by clinical and laboratory subtypes. The APS ACTION registry includes adults who persistently had positivity for aPLs. We evaluated baseline sociodemographic and aPL-related (APS classification criteria and "non-criteria") characteristics of patients overall and in subgroups (aPL-positive without APS, APS overall, thrombotic APS only, obstetric APS only, and both thrombotic APS/obstetric APS). We assessed baseline characteristics of patients tested for the presence of three aPLs (lupus anticoagulant [LAC] test, anticardiolipin antibody [aCL], and anti-β2 -glycoprotein I [anti-β2 GPI]) antibodies by aPL profiles (LAC only, single, double, and triple aPL positivity). The 804 aPL-positive patients assessed in the present study had a mean age of 45 ± 13 years, were 74% female, and 68% White; additionally, 36% had other systemic autoimmune diseases. Of these 804 aPL-positive patients, 80% were classified as having APS (with 55% having thrombotic APS, 9% obstetric APS, and 15% thrombotic APS/obstetric APS). In the overall cohort, 71% had vascular thrombosis, 50% with a history of pregnancy had obstetric morbidity, and 56% had experienced at least one non-criteria manifestation. Among those with three aPLs tested (n=660), 42% were triple aPL-positive. While single-, double-, and triple aPL-positive subgroups had similar frequencies of vascular, obstetric, and non-criteria events, these events were lowest in the single aPL subgroup, which consisted of aCLs or anti-β2 GPI only. Our study demonstrates the heterogeneity of aPL-related clinical manifestations and laboratory profiles in a multicenter international cohort. Within single aPL positivity, LAC may be a major contributor to clinical events. Future prospective analyses, using standardized core laboratory aPL tests, will help clarify aPL risk profiles and improve risk stratification.

Cardiolipin interacts with beta-2-glycoprotein I and forms an open conformation-Mechanisms analyzed using hydrogen/deuterium exchange.

Beta‐2‐glycoprotein I (β2GPI) is the major antigen for the antiphospholipid antibodies in the antiphospholipid syndrome. The exposed epitope in domain I of β2GPI can be recognized by the anti‐β2GPI antibody. Here, we prepared the anionic di‐oleoyl‐phosphatidylserine (DOPS) and cardiolipin (CL) liposomes to interact with the β2GPI. The conformational changes of β2GPI upon binding with the liposomes were analyzed using hydrogen/deuterium exchange mass spectrometry. The exchange level of sequences 21–27 significantly increased after β2GPI had interacted with DOPS. This change indicated a reduced interaction between domain I and domain V, inferring to a protrusion of the sequences 21–27 from the ring conformation. After β2GPI had interacted with CL for 30 min, the exchange levels in 4 of the 5 domains increased significantly. The deuteration levels of sequences 1–20, 21–27, 196–205, 273–279 and 297–306 increased, suggesting that these regions had become more exposed, and the domain I was no longer in contact with domain V. The increasing deuteration levels in sequences 70–86, 153–162, 191–198, 196–205 and 273–279 indicated β2GPI undergoing conformational changes to expose these inner regions, suggesting a structural transition. Overall, DOPS and CL induced minor conformational changes of β2GPI at sequences 21–27 and forms an intermediate conformation after 10 min of interaction. After a complete protein–lipid interaction, high negatively charged CL membrane induced a major conformation transition of β2GPI.

Early Initiation of Anticoagulation Improves the Long-Term Prognosis in Patients With Antiphospholipid Syndrome Associated Portal Vein Thrombosis.

Objectives: Portal vein thrombosis (PVT) is a rare and severe clinical phenotype of antiphospholipid syndrome (APS) with a poor prognosis. Anticoagulation therapy is efficient but is associated with potentially severe bleeding episodes, especially for those patients with thrombocytopenia. We conducted this case-control study to explore the clinical features and associated factors of PVT in APS patients, the re-canalization rate of the PVT after anticoagulation and investigate the beneficial effects of early initiation of anticoagulation in patients with APS associated PVT.Methods: We enrolled patients with APS associated PVT as the case group, and age-, and entry-time-matched APS patients without PVT (1:2) as the control group. We explored the associated factors of PVT in APS patients using multivariate logistic regression analysis. The re-canalization rate of the PVT after anticoagulation was analyzed using the survival analysis.Results: A total of 34 patients (8 males and 26 females) with APS-PVT were enrolled, with a median follow-up time of 3 years (1.5, 7 years). Multivariate logistic regression analysis showed that thrombocytopenia (OR 6.4, 95%CI 1.561–26.218, P = 0.01), hypersensitive c-reactive protein >3 mg/L (OR 4.57, 95%CI 1.426–14.666, P = 0.011), anti β2GPI positive (OR 5, 95%CI 1.816–13.772, P = 0.002) and aPL double-positive (OR 4.08, 95%CI 1.312–12.429, P = 0.013) were independent associated factors for PVT in APS. Survival analysis revealed that effective anticoagulation could increase re-canalization rate significantly (log-rank p = 0.001), with better prognosis (lower mortality rate, log-rank p = 0.045).Conclusions: PVT could be the first presentation of APS with insidious onset and atypical clinical symptoms and easily be misdiagnosed. For patients with APS, double aPLs positive, thrombocytopenia, and inflammation could be the associated factors of PVT. Early diagnosis and anticoagulation treatment can bring thrombus re-canalization thereby significantly improving the prognosis.

The β 2 -Glycoprotein I/HLA-DR Complex As a Major Autoantibody Target in Obstetric Antiphospholipid Syndrome.

The clinical manifestations of antiphospholipid syndrome (APS) include vascular thrombosis and pregnancy morbidity as well as recurrent pregnancy loss (RPL). However, in more than half of patients with RPL, the cause is never determined. Recently, β2 -glycoprotein I (β2 GPI) complexed with HLA class II molecules (β2 GPI/HLA-DR) was found to be a major autoantibody target in APS. The present study was undertaken to assess the serum levels of autoantibodies against the β2 GPI/HLA II complex as a potential risk factor for RPL in women. Serum levels of antiphospholipid antibodies (aPLs), including IgG/IgM anticardiolipin antibodies, IgG/IgM anti-β2 GPI antibodies, and lupus anticoagulant as well as anti-β2 GPI/HLA-DR antibodies, were measured in 227 women with RPL. In this prospective, multicenter, cross-sectional study, women with RPL and their partners underwent HLA-DR immunotyping and analysis to identify potential causes and risk factors associated with RPL. The normal range for anti-β2 GPI/HLA-DR antibody levels was determined using serum samples obtained from a control population of female subjects (208 women of childbearing potential). Of the 227 women with RPL, aPL antibodies were detected in 19.8%, and 52 (22.9%) tested positive for anti-β2 GPI/HLA-DR antibodies. Among the 227 women, 121 (53.3%) had no risk factors for RPL, and among these women with unexplained RPL, 24 (19.8%) were positive for anti-β2 GPI/HLA-DR antibodies. Of the 112 women who had clinical symptoms of APS but did not have levels of aPLs that met the diagnostic criteria for APS, 21 (18.8%) were positive for anti-β2 GPI/HLA-DR antibodies. The anti-β2 GPI/HLA-DR antibody is frequently associated with RPL. Detection of these autoantibodies is useful in understanding the pathogenesis of RPL. Our findings may provide potential new therapeutic strategies for addressing RPL in patients with obstetric APS.

Antiphospholipid Antibody Profile Stability Over Time: Prospective Results From the APS ACTION Clinical Database and Repository.

The APS ACTION Registry studies long-term outcomes in persistently antiphospholipid antibody (aPL)-positive patients. Our primary objective was to determine whether clinically meaningful aPL profiles at baseline remain stable over time. Our secondary objectives were to determine (1) whether baseline characteristics differ between patients with stable and unstable aPL profiles, and (2) predictors of unstable aPL profiles over time. A clinically meaningful aPL profile was defined as positive lupus anticoagulant (LAC) test and/or anticardiolipin (aCL)/anti-β2 glycoprotein-I (anti-β2-GPI) IgG/M ≥ 40 U. Stable aPL profile was defined as a clinically meaningful aPL profile in at least two-thirds of follow-up measurements. Generalized linear mixed models with logit link were used for primary objective analysis. Of 472 patients with clinically meaningful aPL profile at baseline (median follow-up 5.1 yrs), 366/472 (78%) patients had stable aPL profiles over time, 54 (11%) unstable, and 52 (11%) inconclusive. Time did not significantly affect odds of maintaining a clinically meaningful aPL profile at follow-up in univariate (P = 0.906) and multivariable analysis (P = 0.790). Baseline triple aPL positivity decreased (OR 0.25, 95% CI 0.10-0.64, P = 0.004) and isolated LAC test positivity increased (OR 3.3, 95% CI 1.53-7.13, P = 0.002) the odds of an unstable aPL profile over time. Approximately 80% of our international cohort patients with clinically meaningful aPL profiles at baseline remain stable at a median follow-up of 5 years; triple aPL-positivity increase the odds of a stable aPL profile. These results will guide future validation studies of stored blood samples through APS ACTION Core Laboratories.

Necroptotic cell binding of β2 -glycoprotein I provides a potential autoantigenic stimulus in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterized by the development of autoantibodies against diverse self-antigens with damage to multiple organs. Immunization with the SLE autoantigen β2 -glycoprotein I (β2 GPI) and lipopolysaccharide (LPS), a known trigger of necroptosis, induces a murine model of SLE. We hypothesized that necroptotic cells, like apoptotic cells, provide a "scaffold" of cellular self-antigens, but, unlike apoptotic cells, necroptotic cells do so in a proinflammatory and immunogenic context. We demonstrate that β2 GPI indeed binds to necroptotic cells and serves as a target for anti-β2 GPI autoantibodies. We further demonstrate that necroptotic, but not apoptotic, cells promote antigenic presentation of β2 GPI to CD4 T cells by dendritic cells. Finally, we show that β2 GPI/LPS-immunized mice deficient in RIPK3 (receptor-interacting serine/threonine-protein kinase 3) or MLKL (mixed lineage kinase domain like), and consequently unable to undergo necroptosis, have reduced SLE autoantibody production and pathology. RIPK3-/- mice had low levels of SLE autoantibodies and no renal pathology, while MLKL-/- mice produced low levels of SLE autoantibodies initially, but later developed levels comparable with wild type (WT) mice and pathology intermediate to that of WT and RIPK3-/- mice. Serum cytokine levels induced by LPS tended to be lower in RIPK3-/- and MLKL-/- mice than in WT mice, suggesting that impaired proinflammatory cytokine production may impact the initiation of autoantibody production in both strains. Our data suggest that self-antigen (i.e. β2 GPI) presented in the context of necroptosis and proinflammatory signals may be sufficient to overcome immune tolerance and induce SLE.

Antiphospholipid Antibodies in Women with Recurrent Urinary Tract Infection

Background: A variety of infections, including acute and recurrent urinary tract infections (UTIs), can trigger production of antiphospholipid antibodies (aPL). These antibodies in women can lead to recurrent pregnancy loss. The aim of this study was to evaluate the prevalence of aPL in recurrent UTI patients.Materials and Methods: A total 52 subjects who had positive urine culture and 50 healthy individuals as controls were evaluated for presence of lupus anticoagulant (LA), anticardiolipin, anti-β2 GPI(anti-𝛽2-glycoprotein I) autoantibodies IgM and IgG and Interleukin-8 levels. Determination of lupus anticoagulant was done by Activated Partial Thromboplastin Time (aPTT). Anticardiolipin and anti-β2 GPI autoantibodies were evaluated by ELISA method. Interleukin-8 values were also evaluated using ELISA method. Results: Escherichia coli (86.61%) and Proteus mirabilis (1.92%) had the highest and lowest frequency respectively. The prevalence of anti- β2 GPI IgG and IgM isotypes and anticardiolipin IgG and IgM isotypes or LA in UTI patients and healthy controls was 0.0%. There was significant association between neutrophil counts and IL-8 levels at the p < 0.01.Conclusion: Our results showed that in the UTI group and controls evaluated antiphospholipid antibodies were not present. The production of antiphospholipid antibodies is influenced by various genetic and environmental factors and chronic urinary tract infection alone is not the cause. This can affect the prevalence of antiphospholipid antibodies in various populations. However, other factors, such as the type of antiphospholipid antibody, sampling season and methodology can affect the results.

The Impact of Systemic Lupus Erythematosus on the Clinical Phenotype of Antiphospholipid Antibody–Positive Patients: Results From the AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Clinical Database and Repository

Although systemic lupus erythematosus (SLE) is the most common autoimmune disease associated with antiphospholipid antibodies (aPL), limited data exist regarding the impact of SLE on the clinical phenotype of aPL-positive patients. The primary objective of this study was to compare the clinical, laboratory, and treatment characteristics of aPL-positive patients with SLE with those of aPL-positive patients without SLE. A secure web-based data capture system was used to store patient demographic characteristics and aPL-related clinical and laboratory characteristics. Inclusion criteria included positive aPL according to the updated Sapporo classification criteria. Antiphospholipid antibody-positive patients fulfilling the American College of Rheumatology criteria for the classification of SLE ("aPL with SLE") and those with no other autoimmune diseases ("aPL only") were included in the analysis. Six hundred seventy-two aPL-positive patients were recruited from 24 international centers; 426 of these patients did not have other autoimmune disease, and 197 had SLE. The frequency of thrombocytopenia, hemolytic anemia, low complement levels, and IgA anti-β2 -glycoprotein I (anti-β2 GPI) antibodies was higher in the aPL-positive patients with SLE, whereas the frequency of cognitive dysfunction and IgG anti-β2 GPI antibodies was higher in the aPL-only group. The frequency of arterial and venous thromboses (including recurrent) as well as pregnancy morbidity was similar in the 2 groups. The prevalence of cardiovascular disease risk factors at the time of entry into the registry entry did not differ between the 2 groups, with the exception of current smoking, which was more frequent in aPL-positive patients with SLE. Although the frequencies of thrombosis and pregnancy morbidity are similar in aPL-positive patients with and those without SLE, the diagnosis of SLE in patients with persistently positive aPL is associated with an increased frequency of thrombocytopenia, hemolytic anemia, low complement levels, and positive IgA anti-β2 GPI antibodies.

Patients With Systemic Lupus Erythematosus Show an Increased Arterial Stiffness That is Predicted by IgM Anti-β2 -Glycoprotein I and Small Dense High-Density Lipoprotein Particles.

To investigate the metabolic and immunologic factors associated with the presence of central arterial stiffness as measured by the augmentation index (AIx). We conducted a cross-sectional study of 69 female patients with systemic lupus erythematosus (SLE) compared with a control group of 34 healthy women. The anthropometrical variables, the vascular studies, and the analytic data were obtained the same day. The AIx was assessed by peripheral arterial tonometry. The analysis of lipoprotein populations was performed using nuclear magnetic resonance (NMR) spectroscopy. Arterial stiffness was increased in patients with SLE compared with control subjects (mean ± SD 20.30 ± 21.54% versus 10.84 ± 11.51%; P = 0.0021). Values for the AIx were correlated with the Framingham risk score (r = 0.481, P < 0.001), carotid intima-media thickness (r = 0.503, P < 0.001), systolic blood pressure (r = 0.270, P < 0.001), and age (r = 0.365, P < 0.001). Patients receiving antimalarial drugs had a lower AIx (mean ± SD 11.74 ± 11.28% versus 24.97 ± 20.63%; P = 0.024). The AIx was correlated with the atherogenic lipoproteins analyzed by NMR. The immunologic variables associated with the AIx were C4 (r = 0.259, P = 0.046) and IgM anti-β2 -glycoprotein I (IgM anti-β2 GPI) (r = 0.284, P = 0.284). In the multivariate analysis, age (β = 0.347, 95% confidence interval [95% CI] 0.020-0.669, P = 0.035), IgM β2 GPI (β = 0.321, 95% CI 0.024-0.618, P = 0.035) and small dense high-density lipoprotein (HDL) particles (β = 1.288, 95% CI 0.246-2.329, P = 0.017) predicted the AIx. SLE patients had increased arterial stiffness compared with healthy control subjects. Arterial stiffness was decreased in patients treated with antimalarial drugs. Age, IgM β2 GPI, and the number of small dense HDL particles predicted the AIx.

Immunoglobulin A anti-phospholipid antibodies in Swedish cases of systemic lupus erythematosus: associations with disease phenotypes, vascular events and damage accrual.

Immunoglobulin (Ig) G- and IgM-class anti-cardiolipin antibodies (aCL) and lupus anti-coagulant (LA) are included in the 1997 update of the American College of Rheumatology (ACR-97) systemic lupus erythematosus (SLE) criteria. Despite limited evidence, IgA-aCL and IgA anti-β2 -glycoprotein-I (anti-β2 GPI) were included in the 2012 Systemic Lupus International Collaborating Clinics criteria. The present study aimed to evaluate IgG-/IgA-/IgM-aCL and anti-β2 GPI occurrence in relation to disease phenotype, smoking habits, pharmacotherapy, anti-phospholipid syndrome (APS) and organ damage among 526 Swedish SLE patients meeting ACR-97. Patients with rheumatoid arthritis (n=100), primary Sjögren's syndrome (n=50) and blood donors (n=507) served as controls. Anti-phospholipid antibodies (aPL) were analysed by fluoroenzyme-immunoassays detecting aCL/anti-β2 GPI. Seventy-six (14%) SLE cases fulfilled the Sydney APS-criteria, and ≥1 aCL/anti-β2 GPI isotype (IgG/IgA/IgM) occurred in 138 SLE patients (26%). Forty-five (9%) of the SLE cases had IgA-aCL, 20 of whom (4%) lacked IgG-/IgM-aCL. Seventy-four (14%) tested positive for IgA anti-β2 GPI, 34 (6%) being seronegative regarding IgG/IgM anti-β2 GPI. Six (1%) had APS manifestations but were seropositive regarding IgA-aCL and/or IgA anti-β2 GPI in the absence of IgG/IgM-aPL and LA. Positive LA and IgG-aPL tests were associated with most APS-related events and organ damage. Exclusive IgA anti-β2 GPI occurrence associated inversely with Caucasian ethnicity [odds ratio (OR)=0·21, 95% confidence interval (CI)=0·06-0·72) and photosensitivity (OR=0·19, 95% CI=0·05-0·72). Nephritis, smoking, LA-positivity and statin/corticosteroid-medication associated strongly with organ damage, whereas hydroxychloroquine-medication was protective. In conclusion, IgA-aPL is not rare in SLE (16%) and IgA-aPL analysis may have additional value among SLE cases with suspected APS testing negative for other isotypes of aPL and LA.

Antiphospholipid Antibodies Inhibit Trophoblast Toll-Like Receptor and Inflammasome Negative Regulators.

Women with antiphospholipid antibodies (aPL) are at risk for pregnancy complications associated with poor placentation and placental inflammation. Although these antibodies are heterogeneous, some anti-β2 -glycoprotein I (anti-β2 GPI) antibodies can activate Toll-like receptor 4 (TLR-4) and NLRP3 in human first-trimester trophoblasts. The objective of this study was to determine the role of negative regulators of TLR and inflammasome function in aPL-induced trophoblast inflammation. Human trophoblasts were not treated or were treated with anti-β2 GPI aPL or control IgG in the presence or absence of the common TAM (TYRO3, AXL, and Mer tyrosine kinase [MERTK]) receptor ligand growth arrest-specific protein 6 (GAS6) or the autophagy-inducer rapamycin. The expression and function of the TAM receptor pathway and autophagy were measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blotting, and enzyme-linked immunosorbent assay (ELISA). Antiphospholipid antibody-induced trophoblast inflammation was measured by qRT-PCR, activity assays, and ELISA. Anti-β2 GPI aPL inhibited trophoblast TAM receptor function by reducing cellular expression of the receptor tyrosine kinases AXL and MERTK and the ligand GAS6. The addition of GAS6 blocked the effects of aPL on the TLR-4-mediated interleukin-8 (IL-8) response. However, the NLRP3 inflammasome-mediated IL-1β response was not affected by GAS6, suggesting that another regulatory pathway was involved. Indeed, anti-β2 GPI aPL inhibited basal trophoblast autophagy, and reversing this with rapamycin inhibited aPL-induced inflammasome function and IL-1β secretion. Basal TAM receptor function and autophagy may serve to inhibit trophoblast TLR and inflammasome function, respectively. Impairment of TAM receptor signaling and autophagy by anti-β2 GPI aPL may allow subsequent TLR and inflammasome activity, leading to a robust inflammatory response.

Altered β2‐glycoprotein I expression on microparticles in the presence of antiphospholipid antibodies

Essentials β2 glycoprotein-I (β2 GPI) is a scavenger molecule that binds to microparticles (MPs). β2 GPI expression on MPs was measured in systemic lupus erythematosus (SLE) patients and controls. β2 GPI positive MPs is depressed among SLE patients positive for antiphospholipid antibodies. Complex formation between β2 GPI on MPs and patients own anti-β2 GPI may disturb MP clearance. Click to hear an ISTH Academy presentation on antiphospholipid antibody syndrome by Drs de Laat and Bertolaccini SUMMARY: Background Antiphospholipid antibodies (aPLs) together with thrombosis and/or pregnancy morbiditiescharacterize the antiphospholipid syndrome. β2 -GlycoproteinI (β2 GPI), the most important antigen for aPLs, is a scavenger molecule that specifically binds to phosphatidylserine (PS) expressed on microparticles (MPs). Objectives To evaluate β2 GPI-expressing MPs in patients with systemic lupus erythematosus (SLE) stratified for aPL status, and in healthy controls. Patients/Methods We investigated 18 aPL/anti-β2 GPI-positive and 22 aPL-negative patients from a large SLE cohort and 19 healthy controls. β2 GPI-positive MPs and IgG-positive MPs were detected by flow cytometry. We measured plasma levels of β2 GPI, and performed invitro experiments to investigate the binding properties of β2 GPI on MPs. Results SLE patients had more MPs and IgG-positive MPs than controls. We observed fewer β2 GPI-positive MPs in aPL/anti-β2 GPI-positive patients than in aPL/anti-β2 GPI-negative patients and controls (approximately two-fold). β2 GPI levels in plasma did not differ with aPL/anti-β2 GPI status in patients; however, controls had slightly higher levels of β2 GPI than aPL/anti-β2 GPI-positive patients. Invitro experiments revealed that β2 GPI preferentially binds to PS-positive MPs. Conclusions Despite abundant total MPs and MPs in immune complexes, β2 GPI-positive MPs were depleted in SLE patients, and the levels were especially low in aPL/anti-β2 GPI-positive patients. We suggest that anti-β2 GPI antibodies bind to β2 GPI-PS complexes expressed on MPs. Consequent loss of β2 GPI-PS expression on MPs may impair scavenging and contribute to the accumulation ofcirculating PS-negative MPs, a possible source of autoantigens. Autoantibodies delaying MP clearance may thus constitute an important mechanism underlying autoimmunity.

Evaluation of Serum Auto Antibodies in Multiple Sclerosis Patients: A Case Control Study

Background and Purpose: Multiple sclerosis (MS) is believed to be an immune-mediated disorder that develops from an interaction of the individual's genetic and as yet unidentified environmental causes. The prevalence of auto-antibodies in multiple sclerosis patients and their clinical associations vary in various studies. The aim of this study was to determine serum auto antibodies in multiple sclerosis patients. Methods: This cross-sectional case-control study investigated anti-phospholipids antibody (APLA), antinuclear antibody (ANA), anti-cardiolipin antibody (ACLA), anti-neutrophilic antibodies (ANCA), anti-beta-2-glycoprotein I (anti β2GPI), and anti-double strand DNA (anti-ds-DNA) in 54 consecutive patients with relapsing remitting multiple sclerosis (RRMS) and clinically isolated syndrome (CIS) who were referred to Imam Reza outpatient clinic of Shiraz University of Medical Sciences. The results were compared with 25 healthy individuals as the control group. Results : Among 54 patients with relapsing-remitting MS or clinically isolated syndrome, at least one abnormal tests were found in 15 patients (27.9%), 6 (11.1%) had positive antinuclear antibodies, 3 (5.6%) had positive anti cardiolpin antibody (ACLA) and P-ANCA was positive in 2(3.7%) of patients and C-ANCA was positive in 1(1.9%) of patients. None of the patients had any clinical manifestations other than MS symptoms. In the patient group, anti-ds-DNA antibody was positive in 5.6% of cases; statistically it had no significant difference with the control group (0%) (P=0.7), but anti- phospholipids antibody (APLA) and B2GPI were negative in all patient and control groups. The females had more positive auto-antibodies in comparison to males, but statistically their difference was not significant. Conclusion: The results of this study showed that a significant number of patients with relapsing remitting multiple sclerosis and clinically isolated syndrome have positive serum auto-antibodies tests (including ANA, ANCA and ACLA) without clinical expression of any other autoimmune disease.

Evaluation of role of FV, FVIII and APLAs in the pathogenesis of APCR in FV Leiden negative DVT patients: a study in India

Resistance to APC (APCR) is a very important cause of thrombophilia and most frequently caused by the Leiden mutation. APCR is also seen in the absence of FV Leiden and associated with elevated levels of factor V (FV), factor VIII (FVIII) and antiphospholipid antibodies (APLAs). The aim of this prospective case control study was to find out the frequency and role of FV, FVIII and APLAs in the pathogenesis of APCR in FV Leiden negative deep vein thrombosis (DVT) patients in India. A total 30 APCR positive and FV Leiden negative patients with DVT and similar number of age and sex matched healthy controls were recruited. Significantly higher mean FVIII levels were observed in patients as compared to controls [patients: 132.3 ± 30.7IU/ml, controls: 117.5 ± 17.7IU/ml, p = 0.025]. A significant negative correlation was also observed between FVIII and APC ratio (Pearson correlation = 0.368, p = <0.001). Mean FV levels in patients [107.1 ± 13.1IU/ml] and controls [102 ± 11.9IU/ml] were not statistically significant (p = 0.119). Anti β2 glycoprotein I (Anti-β2-GPI, IgG) showed significant association with APCR phenotype (p = 0.050), unlike other factors such as protein C, protein S, lupus anticoagulant and anticardiolipin antibodies. The strong association of FVIII and anti-β2 GPI (IgG) antibodies with APCR phenotype is suggestive of incorporation of these factors in APCR positive DVT patients in the absence of FV Leiden mutation in India. However more studies in large sample size are required for setting up the proper investigation protocol in these patients.

Effects of anti β2-GPI antibodies for choriocarcinoma cell and normal trophoblast cells

Effects of anti β2-GPI antibodies for choriocarcinoma cell and normal trophoblast cells

Performance Characteristics of Commercial Immunoassays for the Detection of IgG and IgM Antibodies to β2 Glycoprotein I and an Initial Assessment of Newly Developed Reference Materials for Assay Calibration.

To investigate the performance characteristics and impact of newly developed reference calibrators on the commutability between anti-β2 glycoprotein I (anti-β2 GPI) immunoassays in antiphospholipid syndrome (APS) and/or systemic lupus erythematosus (SLE). Immunoglobulin G (IgG) and immunoglobulin M (IgM) anti-β2 GPI immunoassays from four manufacturers were evaluated. Serum samples from 269 patients (APS only, n = 31; SLE and APS, n = 83; SLE only, n = 129; pregnancy-related clinical manifestations without APS, n = 26) and 162 women with histories of successful pregnancies were tested. Results were expressed in kit-specific arbitrary units and in the calibrator reference units (RUs) based on 99th percentile cutoff values. Diagnostic accuracies, correlation between kits, and specific clinical manifestations in APS were investigated. The sensitivities of the assays ranged from 15.8% to 27.2% (IgG) and 12.3% to 15.8% (IgM) while specificities ranged from 79.4% to 86.5% (IgG) and 80.6% to 84.5% (IgM). There was moderate to almost perfect interassay reliability (Cohen κ, 0.69-0.98), and Spearman correlation coefficients were generally improved when results of the IgG determinations were expressed in RUs. Although qualitative agreements between immunoassays for both antibody isotypes are acceptable, correlations with APS clinical manifestations were kit dependent. Only the use of IgG reference material improved quantitative correlations between assays.