International consensus on the prevention of venous and arterial thrombotic events in patients with inflammatory bowel disease.

Patients with inflammatory bowel disease (IBD) are at increased risk of thrombotic events. Therapies for IBD have the potential to modulate this risk. The aims of this Evidence-Based Guideline were to summarize available evidence and to provide practical recommendations regarding epidemiological aspects, prevention and drug-related risks of venous and arterial thrombotic events in patients with IBD. A virtual meeting took place in May 2020 involving 14 international IBD experts and 3 thrombosis experts from 12 countries. Proposed statements were voted upon in an anonymous manner. Agreement was defined as at least 75% of participants voting as 'fully agree' or 'mostly agree' with each statement. For each statement, the level of evidence was graded according to the Scottish Intercollegiate Guidelines Network (SIGN) grading system. Consensus was reached for 19 statements. Patients with IBD harbour an increased risk of venous and arterial thrombotic events. Thromboprophylaxis is indicated during hospitalization of any cause in patients with IBD. Disease activity is a modifiable risk factor in patients with IBD, and physicians should aim to achieve deep remission to reduce the risk. Exposure to steroids should be limited. Antitumour necrosis factor agents might be associated with a reduced risk of thrombotic events

Added value of antiphosphatidylserine/prothrombin antibodies in the workup of obstetric antiphospholipid syndrome : communication from the ISTH SSC subcommittee on lupus anticoagulant/antiphospholipid antibodies

Background: The added value of antiphosphatidylserine/prothrombin antibodies (aPS/ PT) in the diagnostic workup of antiphospholipid syndrome (APS) is unclear. Currently, diagnosis of thrombotic APS (TAPS) and obstetric APS (OAPS) requires persistent presence of lupus anticoagulant (LAC), anticardiolipin (aCL) immunoglobulin (Ig) G/IgM, or anti-beta 2- glycoprotein I (a beta 2GPI) IgG/IgM antibodies. Objectives: To evaluate the role of aPS/PT IgG and IgM in OAPS. Methods: aPS/PT IgG/IgM, aCL IgG/IgM, a beta 2GPI IgG/IgM, and LAC were determined in 653 patients (OAPS, TAPS, and controls). In-house aPS/PT cut-off values were calculated, titers and prevalence were compared between OAPS, TAPS, and controls and type of pregnancy morbidity. Sensitivity, specificity, likelihood ratios, and odds ratios (OR) with 95% CI were calculated. Results: In OAPS, aPS/PT IgG and IgM showed an OR of 4.32 (95% CI, 2.54-7.36) and 3.37 (95% CI, 1.93-5.89), respectively, but the association was not independent of LAC. Prevalence and titers of aPS/PT IgG and IgM were lower in OAPS than in patients with TAPS. aPS/PT were more prevalent and showed higher titers in patients with late pregnancy loss than in patients with early pregnancy loss with a positivity of 86.4% and 39.3%, respectively. Higher aPS/PT titers did not increase the likelihood of having OAPS. Conclusion: The added value of aPS/PT testing in the current diagnostic workup of OAPS seems limited compared with LAC, aCL, and a beta 2GPI. aPS/PT might be useful in specific subsets of patients with OAPS. However, future multicentric studies are needed to elucidate the risk of less frequent and most severe obstetrical manifestations

Variability in exposure of epitope G40-R43 of domain i in commercial anti-beta2-glycoprotein I IgG ELISAs.

BACKGROUND: A major problem for diagnosing the antiphospholipid syndrome (APS) is the high variability between commercial anti-β2glycoprotein I (β2GPI) assays. Predominantly antibodies reactive against cryptic epitope Glycine40-Arginine43 (G40-R43) in domain I are associated with an increased risk for thrombosis. Upon interaction with anionic surfaces β2GPI opens up, thereby exposing G40-R43. OBJECTIVES: To examine whether suboptimal exposure of epitope G40-R43 explains the variations in results observed between commercial assays. METHODS: Two patient-derived monoclonal antibodies were tested on neutral versus anionic plates. Antibody P1-117 reacts with G40-R43 in the open conformation while P2-6 recognizes β2GPI irrespective of its conformation. These antibodies were tested in commercial anti-β2GPI assays (A-E). RESULTS: In assay A, both antibodies showed equal reactivity towards β2GPI, indicating that all the β2GPI exposes G40-R43. In other assays P1-117 displayed lower reactivity than P2-6, demonstrating reduced G40-R43 availability. To exclude influences of other assay features, reactivity was re-examined on plates of assay A and B using the protocol/reagents from each assay. In all combinations, reactivity of both antibodies on a plate was comparable to results obtained with its own protocol/reagents, suggesting that the coating, rather than other assay components, accounts for the observed differences. In two patient cohorts we demonstrated that a number of domain I-reactive samples are missed in assays characterized by a decreased exposure of epitope G40-R43. CONCLUSIONS: Exposure of epitope G40-R43 on β2GPI is highly variable between commercial anti-β2GPI assays. As a consequence, patients can be falsely assigned negative in assays characterized by a reduced exposure of G40-R43

Variability in exposure of epitope G40-R43 of domain in manual and automated commercial anti-beta2-glycopreotein I IgG immunoassays

C

Systematic Review of Antiphospholipid Antibodies in COVID-19 Patients: Culprits or Bystanders?

International audiencePurpose of review: COVID-19 patients have a procoagulant state with a high prevalence of thrombotic events. The hypothesis of an involvement of antiphospholipid antibodies (aPL) has been suggested by several reports. Here, we reviewed 48 studies investigating aPL in COVID-19 patients.Recent findings: Prevalence of Lupus Anticoagulant (LA) ranged from 35% to 92% in ICU patients. Anti-cardiolipin (aCL) IgG and IgM were found in up to 52% and up to 40% of patients respectively. Anti-β2-glycoprotein I (aβ2-GPI) IgG and IgM were found in up to 39% and up to 34% of patients respectively. Between 1% and 12% of patients had a triple positive aPL profile. There was a high prevalence of aβ2-GPI and aCL IgA isotype. Two cohort studies found few persistent LA but more persistent solid phase assay aPL over time. aPL determination and their potential role is a real challenge for the treatment of this disease

A new pro-thrombotic mechanism of neutrophil extracellular traps in antiphospholipid syndrome: impact on activated protein C resistance

International audienceAbstract Objectives In APS, precise evaluation of thrombotic risk is a major challenge. Different players, such as activated protein C (APC) resistance or neutrophil extracellular traps (NETs) contribute to the risk of thrombosis. Nevertheless, no study has investigated the interaction between these actors. The main objective of this study was to investigate the relation between NETs and APC resistance. Methods We designed a cross-sectional study including APS/antiphospholipid antibodies (aPL) patients and patients with autoimmune diseases (AID). We performed thrombin generation tests without and with APC to determine APC resistance. To evaluate circulating NETs, we measured plasma levels of MPO-DNA complexes and cell-free DNA with ELISA. Results We recruited 117 patients with definite APS/aPL or AID. We found a positive correlation between NETs and APC resistance, in APS patients and specifically in patients with high thrombotic risk, displaying LA or positivity of all three aPL tests (triple+), or anti-domain I IgG (aDI+). All these patient subgroups had increased NETs concentrations and APC resistance. As the risk profile for thrombosis increased, the relationship between NETs and APC resistance was stronger. Conclusion We have shown that NETs participate in the hypercoagulable state of APS patients by contributing to APC resistance, in particular in high-risk patients. In these most at-risk patients, a targeted action on NETs could reduce APC resistance and constitute a new therapeutic approach in the treatment of APS patients in addition to antithrombotic therapy

Variability in Exposure of Epitope G40-R43 of Domain I in Commercial Anti-Beta2-Glycoprotein I IgG ELISAs

A major problem for diagnosing the antiphospholipid syndrome (APS) is the high variability between commercial anti-\u3b22glycoprotein I (\u3b22GPI) assays. Predominantly antibodies reactive against cryptic epitope Glycine40-Arginine43 (G40-R43) in domain I are associated with an increased risk for thrombosis. Upon interaction with anionic surfaces \u3b22GPI opens up, thereby exposing G40-R43. OBJECTIVES: To examine whether suboptimal exposure of epitope G40-R43 explains the variations in results observed between commercial assays. METHODS: Two patient-derived monoclonal antibodies were tested on neutral versus anionic plates. Antibody P1-117 reacts with G40-R43 in the open conformation while P2-6 recognizes \u3b22GPI irrespective of its conformation. These antibodies were tested in commercial anti-\u3b22GPI assays (A-E). RESULTS: In assay A, both antibodies showed equal reactivity towards \u3b22GPI, indicating that all the \u3b22GPI exposes G40-R43. In other assays P1-117 displayed lower reactivity than P2-6, demonstrating reduced G40-R43 availability. To exclude influences of other assay features, reactivity was re-examined on plates of assay A and B using the protocol/reagents from each assay. In all combinations, reactivity of both antibodies on a plate was comparable to results obtained with its own protocol/reagents, suggesting that the coating, rather than other assay components, accounts for the observed differences. In two patient cohorts we demonstrated that a number of domain I-reactive samples are missed in assays characterized by a decreased exposure of epitope G40-R43. CONCLUSIONS: Exposure of epitope G40-R43 on \u3b22GPI is highly variable between commercial anti-\u3b22GPI assays. As a consequence, patients can be falsely assigned negative in assays characterized by a reduced exposure of G40-R43

Multiple Arterial Thrombosis in a 78-Year-Old Patient: Catastrophic Thrombotic Syndrome in COVID-19

International audienceWe describe a patient with coronavirus disease 2019 (COVID-19) and multiple concomitant thromboses occurring on the 9th day of hospital stay. Thromboses were found in distinct zones of the aorta, as well as in the renal, humeral, and pulmonary arteries. The extensive biological workup performed following this catastrophic thrombotic syndrome found no evidence for underlying prothrombotic disease. In light of current evidence regarding endothelium abnormalities related to COVID-19, this extreme case of catastrophic thrombotic syndrome suggests that COVID-19 can induce severe arterial thrombosis following intense endothelial activation