A pro-thrombotic condition was described in 1983 which was characterised by the presence of circulating antiphospholipid antibodies, as well as peripheral thrombosis (e.g. DVT), a tendency to internal organ involvement, repeated miscarriage, and, occasionally, thrombocytopenia (aPL) (Hughes, Br Med J 287:1088-1089, 1983). Previously, there had been a number of observations, mainly in patients with lupus having "false positive" tests for syphilis, miscarriage and circulating lupus anticoagulants. The description in 1983 had three notable features (a) a detailed comprehensive clinical picture of the syndrome; (b) this description differed from other coagulopathies in showing a propensity for arterial thrombosis (e.g. stroke and heart attack); and (c) this was a syndrome quite independent from lupus. There are indications that the primary antiphospholipid syndrome will turn out to be more common than lupus, though this could still be a reflection of referral practice.

To develop new antiphospholipid syndrome (APS) classification criteria with high specificity for use in observational studies and trials, jointly supported by the American College of Rheumatology (ACR) and EULAR.

Unlike classic APS, CAPS causes multiple microthrombosis due to an increased inflammatory response, known as a “thrombotic storm”. CAPS typically develops after infection, trauma, or surgery and begins with the following symptoms: fever, thrombocytopenia, muscle weakness, visual and cognitive disturbances, abdominal pain, renal failure, and disseminated intravascular coagulation. Although the presence of antiphospholipid antibodies in the blood is one of the diagnostic criteria, the level of these antibodies can fluctuate significantly, which complicates the diagnostic process and can lead to erroneous interpretation of rapidly developing symptoms. Triple therapy is often used to treat CAPS, which includes the use of anticoagulants, plasmapheresis, and high doses of glucocorticosteroids and, in some cases, additional intravenous immunoglobulins. The use of LMWH is recommended as the drug of choice due to its anti-inflammatory and anticoagulant properties. CAPS is a multifactorial disease that requires not only an interdisciplinary approach but also highly qualified medical care, adequate and timely diagnosis, and appropriate prevention in the context of relapse or occurrence of the disease. Improved new clinical protocols and education of medical personnel regarding CAPS can significantly improve the therapeutic approach and reduce mortality rates.

Increasing evidence suggests that autoantibodies directly contribute to hypercoagulability in the antiphospholipid syndrome (APS). One proposed mechanism is the antibody-induced expression of tissue factor (TF) by blood monocytes. Dilazep, an antiplatelet agent, is an adenosine uptake inhibitor known to block induction of monocyte TF expression by bacterial lipopolysaccharide. In the current study we characterized the effects of immunoglobulin G (IgG) from patients with APS on monocyte TF activity and investigated whether dilazep is capable of blocking this effect. IgG from 13 of 16 patients with APS significantly increased monocyte TF activity, whereas normal IgG had no effect. Time-course experiments demonstrated that APS IgG-induced monocyte TF mRNA levels were maximal at 2 hours and TF activity on the cell surface was maximal at 6 hours. Dilazep inhibited antibody-induced monocyte TF activity in a dose-dependent fashion but had no effect on TF mRNA expression. The effect of dilazep was blocked by theophylline, a nonspecific adenosine receptor antagonist. In conclusion, IgG from certain patients with APS induce monocyte TF activity. Dilazep inhibits the increased expression of monocyte TF activity at a posttranscriptional level, probably by way of its effect as an adenosine uptake inhibitor. Pharmacologic agents that block monocyte TF activity may be a novel therapeutic approach in APS.

In the antiphospholipid syndrome (APS), antiphospholipid antibody (aPL) recognition of β2 glycoprotein I promotes thrombosis, and preclinical studies indicate that this is due to endothelial nitric oxide synthase (eNOS) antagonism via apolipoprotein E receptor 2 (apoER2)-dependent processes. How apoER2 molecularly links these events is unknown. Here, we show that, in endothelial cells, the apoER2 cytoplasmic tail serves as a scaffold for aPL-induced assembly and activation of the heterotrimeric protein phosphatase 2A (PP2A). Disabled-2 (Dab2) recruitment to the apoER2 NPXY motif promotes the activating L309 methylation of the PP2A catalytic subunit by leucine methyl transferase-1. Concurrently, Src homology domain-containing transforming protein 1 (SHC1) recruits the PP2A scaffolding subunit to the proline-rich apoER2 C terminus along with 2 distinct regulatory PP2A subunits that mediate inhibitory dephosphorylation of Akt and eNOS. In mice, the coupling of these processes in endothelium is demonstrated to underlie aPL-invoked thrombosis. By elucidating these intricacies in the pathogenesis of APS-related thrombosis, numerous potential new therapeutic targets have been identified.© 2018 by The American Society of Hematology.

The antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity in the presence of antiphospholipid antibodies, including anti-β2-glycoprotein-I (anti-β2GPI), that are considered central to APS pathogenesis. Based on animal studies showing a role of complement in APS-related clinical events, we used the modified Ham (mHam) assay (complement-dependent cell killing) and cell-surface deposition of C5b-9 to test the hypothesis that complement activation is associated with thrombotic events in APS. A positive mHam (and corresponding C5b-9 deposition) were present in 85.7% of catastrophic APS (CAPS), 35.6% of APS (and 68.5% of samples collected within 1 year of thrombosis), and only 6.8% of systemic lupus erythematosus (SLE) sera. A positive mHam assay was associated with triple positivity (for lupus anticoagulant, anticardiolipin, and anti-β2GPI antibodies) and recurrent thrombosis. Patient-derived anti-β2GPI antibodies also induced C5b-9 deposition, which was blocked completely by an anti-C5 monoclonal antibody, but not by a factor D inhibitor, indicating that complement activation by anti-β2GPI antibodies occurs primarily through the classical complement pathway. Finally, patients with CAPS have high rates of rare germline variants in complement regulatory genes (60%), compared with patients with APS (21.8%) or SLE (28.6%) or normal controls (23.3%), and have mutations at a rate similar to that of patients with atypical hemolytic uremic syndrome (51.5%). Taken together, our data suggest that anti-β2GPI antibodies activate complement and contribute to thrombosis in APS, whereas patients with CAPS have underlying mutations in complement regulatory genes that serve as a "second hit," leading to uncontrolled complement activation and a more severe thrombotic phenotype.© 2020 by The American Society of Hematology.

\n Antiphospholipid antibodies (aPL), especially those targeting β\n 2\n ‐glycoprotein I (β\n 2\n GPI), are well known to activate endothelial cells, monocytes, and platelets, with prothrombotic implications. In contrast, the interaction of aPL with neutrophils has not been extensively studied. Neutrophil extracellular traps (NETs) have recently been recognized as an important activator of the coagulation cascade, as well as an integral component of arterial and venous thrombi. This study was undertaken to determine whether aPL activate neutrophils to release NETs, thereby predisposing to the arterial and venous thrombosis inherent in the antiphospholipid syndrome (APS).\n

Thrombotic antiphospholipid syndrome (APS) is a condition in which thrombosis in venous, arterial, and/or small vessels is ascribed to the presence of antiphospholipid antibodies (aPL). Among the various proposed pathogenic theories to explain thrombotic APS, those involving the interaction between aPL and the protein C system have gained much consensus. Indeed, robust data show an acquired activated protein C resistance (APC-R) in these patients. The role of aPL in this impairment is clear, but the mechanism of action is uncertain, as the type of aPL and to what extent aPL are involved remains a gray area. Lupus anticoagulant (LA) is often associated with APC-R, but antibodies generating LA comprise those directed to β2-glycoprotein I and antiphosphatidylserine/prothrombin. Moreover, the induction of APC-R by aPL requires the presence of phospholipids and is suppressed by the presence of an excess of phospholipids. How phospholipids exposed on the cell membranes work in the system in vivo is unknown. Interestingly, acquired APC-R due to aPL might explain the clinical phenotypes of thrombotic APS. Indeed, the literature reports cases of both venous and arterial thromboembolism as well as skin necrosis, the latter observed in the severe form of protein C deficiency and in catastrophic APS.Thieme. All rights reserved.

The combined presence of anti-phospholipid (PL) Ab, including lupus anticoagulants (LAC) and/or anticardiolipin Ab (aCL), and thrombosis is recognized as the antiphospholipid syndrome (APS). LAC are detected as an inhibitory effect on PL-restricted in vitro blood coagulation tests, and are comprised mainly of Ab against β2 glycoprotein I and prothrombin (PT). Recently, anti-PT Ab (aPT) were found to be associated with thrombosis by some investigators, although this is not confirmed by others. Considering that aPT are heterogeneous in patients and that PT is converted into thrombin, we hypothesize that certain aPT in patients may bind to thrombin, and that some of such anti-thrombin Ab may interfere with thrombin-antithrombin (AT) interaction and thus reduce the AT inactivation of thrombin. To test this hypothesis, we searched for anti-thrombin Ab in APS patients and then studied those found for their effects on the AT inactivation of thrombin. The results revealed that most, but not all, aPT-positive patient plasma samples contained anti-thrombin Ab. To study the functional significance of these Ab, we identified six patient-derived mAb that bound to both PT and thrombin. Of these mAb, three could reduce the AT inactivation of thrombin, whereas others had minimal effect. These findings indicate that some aPT in patients react with thrombin, and that some of such anti-thrombin Ab could inhibit feedback regulation of thrombin. Because the latter anti-thrombin Ab are likely to promote clotting, it will be important to develop specific assays for such Ab and study their roles in thrombosis in APS patients.

The causes of thrombosis and pregnancy loss in antiphospholipid syndrome (APS) are still unknown, although several hypotheses have been proposed and hypofibrinolysis has been implicated. Anti–tissue-type plasminogen activator (tPA) antibodies may induce fibrinolytic defects and preliminary data indicate an association with thrombosis in APS. We measured plasma anti-tPA antibody levels in 91 consecutive patients with APS, 91 healthy controls, 40 patients with antiphospholipid antibodies without APS symptoms, and 23 patients with systemic lupus erythematosus (SLE) without antiphospholipid antibodies and APS symptoms. Patients with APS had anti-tPA antibody levels higher than controls (P =.0001), patients with SLE (P =.0001), and asymptomatic antiphospholipid patients (P =.05). A subgroup of 53 patients had plasma levels of tPA antigen higher (P =.0001) and tPA activity lower (P =.05) than controls, with an inverse correlation (r = –0.454; P =.003) between anti-tPA antibody levels and tPA activity and no correlation with tPA antigen. The 2 patients with the highest antibody levels had tPA activity below the normal range. Their antibodies were, respectively, IgG1 and IgG3; both recognized human tPA, recombinant tPA, and the catalytic domain of tPA, but not β2-glycoprotein I, prothrombin, or plasminogen. Our data indicate that anti-tPA antibodies specifically interacting with the catalytic domain of tPA can be found in patients with APS, representing a possible cause of hypofibrinolysis.

The catastrophic antiphospholipid syndrome (CAPS) is a life-threating variant of the antiphospholipid syndrome characterized by the development of multiple thrombosis in a short period of time, usually ending up in the failure of function of several vital organs. Most CAPS episodes are related to a prothrombotic situation or precipitating factor such as infections, surgical procedures or malignant diseases. In patients with CAPS, the development of multiple thrombosis leads to an important cytokine release that worsens the already critical patient's situation. The disease usually involves the kidneys, the lungs and the heart, although any organ system can be affected. Although occasionally the disease affects large vessels, in the majority of cases it affects small vessels, leading to a disseminated microangiopathic syndrome resembling thrombotic thrombocytopenic purpura. Treatment is based on the administration of anticoagulants, corticosteroids, plasma exchange and/or intravenous immunoglobulins. Cyclophosphamide is recommended in those CAPS cases associated to systemic lupus erythematosus. Additionally, rituximab and eculizumab have been used in refractory cases. Mortality is still around 30% despite current treatment.Copyright © 2018. Published by Elsevier Ltd.

To describe the clinical and laboratory features, as well as the precipitating factors, treatment and outcome of patients with catastrophic antiphospholipid syndrome (APS).We analyzed the 280 patients included until September 2008 in the website based international registry of patients with catastrophic APS ("CAPS Registry") (http://www.med.ub.es/MIMMUN/FORUM/CAPS.HTM).The entire series includes 201 (72%) female and 79 (28%) male patients with a mean age of 37 +/- 14 years (range, 11-60 years). A total of 129 (46%) patients suffered from primary APS, 112 (40%) from systemic lupus erythematosus, 14 (5%) from lupus-like disease, and 25 (9%) from other autoimmune diseases. The catastrophic episode was the first manifestation of the APS in 129 (46%) patients. A precipitating factor was reported in 53% of the patients. The first clinical manifestation at the time of the catastrophic episode was a pulmonary complication in 24% of the cases, a neurologic feature in 18% and a renal feature in 18%. During the catastrophic episode, intraabdominal involvement was identified in the majority of patients, mainly consisting of renal (71%), hepatic (33%), gastrointestinal (25%), splenic (19%), adrenal (13%), and pancreatic (8%) manifestations. 123 (44%) patients died at the time of the catastrophic APS event but the higher recovery rate was achieved by the combination of anticoagulants plus corticosteroids plus plasma exchange (PE) and/or intravenous immunoglobulins (IVIG) (69% versus 54%).The catastrophic APS is an uncommon but potentially life-threatening condition that needs high clinical awareness. The therapeutical connotation is that this may be corrected with the combination of anticoagulation plus steroids plus attempts at achieving a prompt reduction of antiphospholipid antibody titer (i.e. PE and/or IVIG).

Catastrophic antiphospholipid syndrome (CAPS) is a rare and potentially life-threatening variant of the antiphospholipid syndrome which is characterised by multiple small vessel thrombosis which can lead to multiorgan failure. CAPS is a clinical emergency which all clinicians need to be aware of because early diagnosis and treatment may improve maternal and fetal outcome. Here, we report a case of CAPS in pregnancy in a 31-year-old female patient who presented at 28 weeks of gestation. A literature review of CAPS in pregnancy and the puerperium is also included.

Catastrophic antiphospholipid syndrome (CAPS) is an uncommon and the most severe form of antiphospholipid syndrome (APS). A 33-week pregnant patient with Klippel-Trenaunay syndrome, past SARS-CoV-2 infection and type I fetal growth restriction with shortening of the fetal long bone was diagnosed in our center with a probable CAPS. Cesarean section was performed four days after the diagnosis due to the torpid evolution of the patient. Clinical improvement was noted a few days later and the mother and baby were discharged within a week. We review the current literature on CAPS during pregnancy and provide an updated view.Copyright © 2021. Published by Elsevier B.V.

抗磷脂综合征（antiphospholipid syndrome，APS）是一种由抗磷脂抗体引起的非炎症性自身免疫病。妊娠合并APS易发生早期反复自然流产，孕晚期胎死宫内，胎儿生长受限，血小板减少，子痫前期或子痫以及胎盘功能障碍等不良妊娠结局，严重危及母儿健康。临床上应充分重视妊娠合并APS的诊断和治疗。

The objective of this study was to assess the effect that triple therapy (anticoagulation plus CS plus plasma exchange and/or IVIGs) has on the mortality risk of patients with catastrophic APS (CAPS) included in the CAPS Registry.Patients from the CAPS Registry were grouped based on their treatments: triple therapy; drugs included in the triple therapy but in different combinations; and none of the treatments included in the triple therapy. The primary endpoint was all-cause mortality. Multivariate logistic regression models were used to compare mortality risk between groups.The CAPS Registry cohort included 525 episodes of CAPS accounting for 502 patients. After excluding 54 episodes (10.3%), a total of 471 patients with CAPS were included [mean (s.d.) age 38.5 years (17); 68.2% female; primary APS patients 62%]. Overall, 174 (36.9%) patients died. Triple therapy was prescribed in 189 episodes (40.1%), other combinations in 270 (57.3%) and none of those treatments in 12 episodes (2.5%); the mortality rate in the three groups was 28.6, 41.1 and 75%, respectively. Triple therapy was positively associated with a higher chance of survival when compared with non-treatment [adjusted odds ratio (OR) = 9.7, 95% CI: 2.3, 40.6] or treatment with other combinations of drugs included in the triple therapy (adjusted OR = 1.7, 95% CI: 1.2, 2.6). No statistical differences were found between patients that received triple therapy with plasma exchange or IVIGs (P = 0.92).Triple therapy is independently associated with a higher survival rate among patients with CAPS.© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The 'Task Force on Catastrophic Antiphospholipid Syndrome (CAPS)' was developed on the occasion of the 14th International Congress on Antiphospholipid Antibodies. The objectives of this Task Force were to assess the current knowledge on pathogenesis, clinical and laboratory features, diagnosis and classification, precipitating factors and treatment of this condition in order to address recommendations for future research. This article summarizes the studies analyzed by the Task Force, its recommendations and the future research agenda.Copyright © 2014 Elsevier B.V. All rights reserved.

Statins are powerful lipid-lowering drugs that inhibit cholesterol biosynthesis via downregulation of hydroxymethylglutaryl coenzyme-A reductase, which are largely used in patients with or at risk of cardiovascular disease. Available data on thromboembolic disease include primary and secondary prevention as well as bleeding and mortality rates in statin users during anticoagulation for VTE. Experimental studies indicate that statins alter blood clotting at various levels. Statins produce anticoagulant effects via downregulation of tissue factor expression and enhanced endothelial thrombomodulin expression resulting in reduced thrombin generation. Statins impair fibrinogen cleavage and reduce thrombin generation. A reduction of factor V and factor XIII activation has been observed in patients treated with statins. It is postulated that the mechanisms involved are downregulation of factor V and activated factor V, modulation of the protein C pathway and alteration of the tissue factor pathway inhibitor. Clinical and experimental studies have shown that statins exert antiplatelet effects through early and delayed inhibition of platelet activation, adhesion and aggregation. It has been postulated that statin-induced anticoagulant effects can explain, at least partially, a reduction in primary and secondary VTE and death. Evidence supporting the use of statins for prevention of arterial thrombosis-related cardiovascular events is robust, but their role in VTE remains to be further elucidated. In this review, we present biological evidence and experimental data supporting the ability of statins to directly interfere with the clotting system.