Venous Thrombosis in the Antiphospholipid Syndrome

Progress in the field of animal models of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by recurrent arteriovenous thrombosis and pathological pregnancy, accompanied by persistent antiphospholipid antibodies, (aPL). The incidence of APS is increasing year by year, clinicians lack of understanding of this type of disease, easy to misdiagnose and miss the diagnosis. Therefore, it is extremely important to establish a suitable animal model to reduce the process of disease development as much as possible and improve clinicians' understanding and understanding. This review will summarize the animal models of APS from the aspects of modeling methods, modeling mechanism, evaluation indicators and advantages and disadvantages of methods, providing a reference for finding an animal model highly similar to human APS, helping researchers to further clarify the pathogenesis of APS and find potential therapeutic targets, so as to achieve early diagnosis, early intervention, and ultimately improve the prognosis of patients.

Heritable Thrombophilia and Increased Risk for Venous Thromboembolism Despite Thromboprophylaxis After Pelvis or Acetabulum Fracture

OBJECTIVES

Individuals with pelvic and acetabular fractures are at high risk of venous thromboembolism (VTE). The purpose of this study was to determine whether serum markers for thrombophilia and rapid thromboelastography (r-TEG) values correlate with increased VTE risk among patients with pelvic and acetabular fractures.

METHODS

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DESIGN

Prospective observational study.

SETTING

Two urban academic level 1 trauma centers.

PATIENT SELECTION CRITERIA

Adult patients with isolated pelvis and/or acetabulum fractures (OTA/AO 61 and 62) treated surgically placed on a standardized VTE chemoprophylaxis regimen with enoxaparin over a 5-year period were included.

OUTCOME MEASURES AND COMPARISONS

Serum r-TEG, coagulation laboratory values, and markers for heritable thrombophilia were drawn postoperatively and after completion of a 6-week course of enoxaparin. The primary outcome was VTE event (either deep venous thrombosis or pulmonary embolism) diagnosed using a Duplex ultrasound, chest computed tomography angiogram, or lung ventilation-perfusion ordered based on clinical suspicion of a VTE event. Laboratory markers and values were then compared between patients who went on to have a VTE event and those who did not and patients with and without markers of thrombophilia.

RESULTS

One hundred thirty-three adult patients with isolated operative pelvic and/or acetabular fractures were enrolled in this study. The average age of patients at time of injury was 48.3 years (range 18-91). Sixty-seven percent of patients in the study were (n = 90) males. Sixty-three percent of patients (n = 84) completed both clinical and laboratory follow-up. Forty-one percent of patients (n = 54) had 1 or more markers of heritable thrombophilia. Twelve percent (n = 10) of patients who completed follow-up were diagnosed with VTE. Age, sex, and smoking status were not associated with VTE. Patients who developed VTE had a higher body mass index (P = 0.04). Having more than 1 marker of heritable thrombophilia (P = 0.004) and an r-TEG mean amplitude greater than 72 mm postoperatively was positively associated with VTE (P = 0.02).

CONCLUSIONS

Among patients treated surgically for isolated pelvic and acetabular fractures who received enoxaparin prophylaxis, the presence of more than 1 marker of heritable thrombophilia or r-TEG mean amplitude value greater than 72 mm postoperatively was associated with an increased risk of VTE.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Incidence of Venous Thromboembolism Among Commonly Prescribed Second-Generation Antipsychotics

Background: Second-generation antipsychotics (SGAs) are commonly prescribed medications used to treat a variety of mental health conditions. Recent data has correlated antipsychotic medications with venous thromboembolism (VTE). SGAs have diverse side effect profiles, which may contribute to differences in incidence of VTE. It is unknown which SGAs confer the most risk, and what the mechanism of increased risk is. Objective: Determine incidence of VTE in Veterans at Veterans Affairs North Texas Health Care System (VA-NTX HCS) between SGAs aripiprazole, olanzapine and risperidone. Methods: Retrospective chart review of adult Veterans at VA-NTX HCS between October 2015 to December 2019 prescribed aripiprazole, olanzapine, or risperidone. Results: Of 823 Veterans, incidence of VTE was lowest in aripiprazole group at .4%, increased to 1.7% in the olanzapine group, and was highest at 2.5% in the risperidone group. However, differences in incidence of VTE between SGAs were not statistically different, indicating no between-group differences. Conclusion: There was no difference in the incidence of VTE between risperidone, olanzapine, or aripiprazole. Given multiple limitations with this study, higher-powered studies should be conducted to investigate the possibility of differences in the incidence of VTE between the SGAs.

A Genome-Wide Association Study Suggests New Susceptibility Loci for Primary Antiphospholipid Syndrome

OBJECTIVE

Primary antiphospholipid syndrome (PAPS) is a rare autoimmune disease characterized by the presence of antiphospholipid antibodies and the occurrence of thrombotic events and pregnancy complications. Our study aimed to identify novel genetic susceptibility loci associated with PAPS.

METHODS

We performed a genome-wide association study comprising 5,485 individuals (482 affected individuals) of European ancestry. Significant and suggestive independent variants from a meta-analysis of approximately 7 million variants were evaluated for functional and biological process enrichment. The genetic risk variability for PAPS in different populations was also assessed. Hierarchical clustering, Mahalanobis distance, and Dirichlet Process Mixtures with uncertainty clustering methods were used to assess genetic similarities between PAPS and other immune-mediated diseases.

RESULTS

We revealed genetic associations with PAPS in a regulatory locus within the HLA class II region near HLA-DRA and in STAT1-STAT4 with a genome-wide level of significance; 34 additional suggestive genetic susceptibility loci for PAPS were also identified. The disease risk allele near HLA-DRA is associated with overexpression of HLA-DRB6, HLA-DRB9, HLA-DQA2, and HLA-DQB2 in immune cells, vascular tissue, and nervous tissue. This association is independent of the association between PAPS and HLA-DRB1*1302. Functional analyses highlighted immune-related pathways in PAPS-associated loci. The comparison with other immune-mediated diseases revealed a close genetic relatedness to neuromyelitis optica, systemic sclerosis, and Sjögren syndrome, suggesting co-localized causal variations close to STAT1-STAT4, TNPO3, and BLK.

CONCLUSION

This study represents a comprehensive large-scale genetic analysis for PAPS and provides new insights into the genetic basis and pathophysiology of this rare disease.

Clinical and Laboratory Diagnosis of Antiphospholipid Syndrome: A Review

The antiphospholipid syndrome (APS) manifests through venous or arterial thrombosis, with or without pregnancy complication alongside the continuous presence of antiphospholipid antibodies (aPL). APS classification relies on three aPL subtypes: anticardiolipin (aCL), anti-β2-glycoprotein I antibodies (anti-β2GPI), and lupus anticoagulants (LA) antibodies. Given that thrombosis and pregnancy issues are not unique to APS, the precise and reliable identification of aPL forms the basis for diagnosis. Semi-quantitative solid-phase assays identify two antibodies, aCL and anti-β2GPI, while LA detection occurs through various phospholipid-dependent coagulation assays that are based on antibody behaviour. LA, specifically, is conclusively associated with thrombosis, prompting discussions around the serological criteria for APS. Despite advancements in LA detection, the standardisation of all aPL detection assays remains imperative. The combined presence of aCL and anti-β2GPI with thrombosis inconsistently triggers concern. Initial presentations by APS patients commonly exhibit a heightened risk of stroke, miscarriages in the later stages of pregnancy, positive results of LA tests, and widespread thrombosis across multiple organs, often leading to adverse outcomes. Correctly diagnosing this condition is pivotal to avoid unnecessary long-term secondary thromboprophylaxis.

Viewpoint: Provoked thrombosis in antiphospholipid syndrome

Unprovoked thrombosis (thrombosis occurring without an established environmental factor favouring the episode) is a classic feature of APS. In the general population, provoked venous thromboembolism (VTE) is clearly defined and has clinical and therapeutic differences compared with unprovoked VTE. Whether provoked VTE in the context of APS may lead to a limited treatment duration is not well established. Therefore, careful clinical and laboratory evaluation is needed to identify patients eligible for a limited duration of anticoagulation treatment after provoked VTE. Given the uncertainties of available data, the risks and benefits of treatment decisions should be clearly explained. Decisions should be shared by both the patient and physician. Cardiovascular risk factors are common in patients with APS with arterial thrombosis. There are insufficient data suggesting that cardiovascular risk factor control would allow the cessation of anticoagulation. In most instances, arterial thrombosis will require prolonged anticoagulants. A careful analysis of clinical characteristics and laboratory evaluation, particularly the aPL antibody profile, is needed to make decisions on a case-by-case basis.

The estimated prevalence of antiphospholipid antibodies and criteria-antiphospholipid syndrome in subjects with renal thrombotic microangiopathy

BACKGROUND

While the prevalence of antiphospholipid antibodies (aPL) in venous and arterial thrombotic events had already been estimated by previous studies, the prevalence of aPL in subjects with Thrombotic Microangiopathy (TMA) is still not fully elucidated. Thus, we conducted a systematic review to estimate the frequency of aPL in subjects with biopsy-proven renal TMA.

METHODS

We conducted in the PubMed database a search for English-language studies investigating the presence of aPL in subjects with biopsy-proven renal TMA from January 1985 to December 2022. Keywords used in the search included: 'antiphospholipid syndrome', 'antiphospholipid antibodies' and 'thrombotic microangiopathy'. Cohorts of HUS patients were excluded due to the risk of over-estimating the prevalence of aPL in these populations. The median frequency for positive aPL including anticardiolipin antibodies (aCL), antibodies against β2-glycoprotein-I (anti-β2GPI) and lupus anticoagulant (LA) was then calculated.

RESULTS

522 articles were identified through the literature search. Six studies, assessing the prevalence of aPL in 211 subjects with renal TMA, were retrieved. The overall aPL prevalence was estimated as 24.4% (range 22-56). The estimated prevalence of aCL (IgG/IgM), anti-β2GPI, (IgG/IgM) and LA was 4.0% (range 3-27), 4.0% (range 3-16) and 18.9% (range 13-25), respectively. APS was diagnosed in 16.3% (range 11-29) of the patients. Of note, a high level of heterogeneity was observed when comparing the reported aPL profiles for each study.

CONCLUSIONS

This comprehensive systematic analysis of studies investigating the prevalence of aPL in renal TMA showed that, despite the high heterogeneity of the included studies, aPL are present in about one case out of four renal-TMA cases.

A genome-wide association study suggests new susceptibility loci for primary antiphospholipid syndrome

Objectives

Primary antiphospholipid syndrome (PAPS) is a rare autoimmune disease characterized by the presence of antiphospholipid antibodies and the occurrence of thrombotic events and pregnancy complications. Our study aimed to identify novel genetic susceptibility loci associated with PAPS.

Methods

We performed a genome-wide association study comprising 5,485 individuals (482 affected individuals) of European ancestry. Significant and suggestive independent variants from a meta-analysis of approximately 7 million variants were evaluated for functional and biological process enrichment. The genetic risk variability for PAPS in different populations was also assessed. Hierarchical clustering, Mahalanobis distance, and Dirichlet Process Mixtures with uncertainty clustering methods were used to assess genetic similarities between PAPS and other immune-mediated diseases.

Results

We revealed genetic associations with PAPS in a regulatory locus within the HLA class II region near HLA-DRA and in STAT4 with a genome-wide level of significance. 34 additional suggestive genetic susceptibility loci for PAPS were also identified. The disease risk allele in the HLA class II locus is associated with overexpression of HLA-DRB6 , HLA-DRB9 , HLA-DPB2 , HLA-DQA2 and HLA-DQB2 , and is independent of the association between PAPS and HLA-DRB1*1302 . Functional analyses highlighted immune and nervous system related pathways in PAPS-associated loci. The comparison with other immune-mediated diseases revealed a close genetic relatedness to neuromyelitis optica, systemic sclerosis, and Sjögren's syndrome, suggesting colocalized causal variations close to STAT4 , TNPO3 , and BLK .

Conclusions

This study represents a comprehensive large-scale genetic analysis for PAPS and provides new insights into the genetic basis and pathophysiology of this rare disease.

Risk of venous thromboembolism in autoimmune diseases: A comprehensive review

Autoimmune diseases have specific pathophysiologic mechanisms leading to an increased risk of arterial and venous thrombosis. The risk of venous thromboembolism (VTE) varies according to the type and stage of the disease, and to concomitant treatments. In this review, we revise the most common autoimmune disease such as antiphospholipid syndrome, inflammatory myositis, polymyositis and dermatomyositis, rheumatoid arthritis, sarcoidosis, Sjogren syndrome, autoimmune haemolytic anaemia, systemic lupus erythematosus, systemic sclerosis, vasculitis and inflammatory bowel disease. We also provide an overview of pathophysiology responsible for the risk of VTE in each autoimmune disorder, and report current indications to anticoagulant treatment for primary and secondary prevention of VTE.

Antiphospholipid Syndrome in Patients with Venous Thromboembolism

Unprovoked (or provoked by mild risk factors) venous thromboembolism (VTE) in young patients, VTE in uncommon sites, or cases of unexplained VTE recurrence may be positive for antiphospholipid antibodies (aPL) and thus may be diagnosed with antiphospholipid syndrome (APS). The evaluation of aPL is standardized using immunological tests for anticardiolipin and anti-β2-glycoprotein I. The determination of functional antibodies (lupus anticoagulant) is less standardized, especially in patients on anticoagulant treatment. Patients positive for all the three tests are at high risk of recurrence, which, in turn, might lead to chronic obstruction of pulmonary vessels (chronic thromboembolic pulmonary hypertension). Randomized clinical trials have shown that triple-positive patients should be treated with vitamin K antagonists maintaining an international normalized ratio between 2 and 3. Whether patients with VTE and incomplete aPL profile can be treated with direct oral anticoagulants should be further investigated.

Venous thromboembolism during pregnancy: Trends, incidence, and risk patterns in a large cohort population

OBJECTIVE

To determine the incidence and risk factors for pregnancy-associated venous thromboembolism (VTE).

METHODS

An observational retrospective study was conducted using data from 452 176 live births between the years 2010 and 2019. The study group consisted of women who were diagnosed with VTE during pregnancy or the postpartum period. The exclusion criteria included women who purchased anticoagulant drugs during pregnancy or postpartum. The hazard ratios (HRs) of VTE per week of each trimester and the postpartum period were calculated.

RESULTS

A total of 421 125 live births were included in the study. Among the study population, 302 cases (0.71 cases/1000 pregnancies) were diagnosed with VTE during pregnancy and postpartum. The overall rates of diagnosis did not change significantly during the study period but followed a declining trend in the postpartum period. The highest risk of VTE was found to be during the third trimester (HR 0.002% per week, 95% confidence interval [CI] 0.0016-0.0023), while the lowest rate was during the postpartum period (HR 0.0007% per week, 95% CI 0.0004-0.0011).

CONCLUSION

Pregnancy and the puerperium are well-established risk factors for VTE. The present study demonstrates a declining trend in the risk and incidence of VTE during the postpartum period, which can be explained by a liberal and effective VTE prevention policy.

A Review of Systemic Hematological Manifestations and Stent Thrombosis

Stent thrombosis (ST) has significant morbidity and mortality following percutaneous coronary intervention (PCI). ST is uncommon making the identification of nonprocedural predictors challenging. Numerous case reports of ST in both benign and malignant hematological conditions exist. Given ST could be a Herald event of an undiagnosed condition and condition-specific treatment may be available, it is important to consider specialist testing in an unexplained ST. This review included a case presentation of ST in previously undiagnosed paroxysmal nocturnal hemoglobinuria (PNH) and a literature review of ST in other acquired thrombophilias including myeloproliferative disorders (MPNs), antiphospholipid syndrome, hematological malignancies, and heparin-induced thrombocytopenia (HIT). Inherited thrombophilias and common pitfalls in thrombophilia and coagulation testing are also discussed. The cardiac-hematology landscape is becoming increasingly complex and there is a paucity of how to best manage ST in these patients. There is clear variability in practice and the use of multidisciplinary input between cardiologists and hematologists is essential.

Demographic, Clinical, and Serological Characteristics of Antiphospholipid Syndrome Patients From the Anticoagulation Clinic of Hospital Universitario San Vicente Fundación, Medellín, Colombia

INTRODUCTION

Antiphospholipid syndrome (APS) is an acquired autoimmune thrombophilia, characterized by vascular thrombosis or obstetric compromise, associated with the presence of antiphospholipid antibodies. Large international studies have analyzed the clinical/serological behavior of the disease and in Colombia, there are few cohorts that have been evaluated.

OBJECTIVE

The main objective is to characterize the patients with APS followed in the anticoagulation clinic of a tertiary care hospital and to determine the clinical manifestations and serological findings at diagnosis.

MATERIALS AND METHODS

A retrospective descriptive study was carried out to evaluate patients with a presumptive and/or confirmed diagnosis of APS, according to modified Sapporo criteria, which fulfilled the inclusion and exclusion criteria established by the authors. The information was collected from the review of medical records.

RESULTS

We included 103 patients, with the female sex being the most prevalent (86.6%). 54.3% of the patients (n = 56) had a diagnosis of primary APS. Venous thrombotic events occurred in 87.3% (n = 90) of the patients, 34.9% (n = 36) had arterial thrombosis (n = 36), and 3.9% (n = 4) had catastrophic APS (n = 4). 15 cases of Obstetric APS were documented. Lupus coagulation inhibitor (LA) positivity was the most prevalent marker in 84% (n = 68) of cases.

CONCLUSIONS

The clinical behavior in this cohort of patients is like that found in large international and national studies. Most patients have a probable diagnosis of APS, so they could overestimate the real prevalence and condition of long-term anticoagulant treatment.

Antiphospholipid Syndrome-Related Pulmonary Embolism: Clinical Characteristics and Early Recognition

Background

Pulmonary thromboembolism is a common disease frequently encountered in the emergency room and has a high mortality rate. Antiphospholipid syndrome (APS) is a high-risk factor for recurrent pulmonary embolism (PE). It is critical to effectively administer anticoagulants to avoid the recurrence of thrombotic events. This study aims to identify the clinical characteristics of APS patients with PE (APS-PE) and to develop a risk score for determining the presence of APS in PE patients in the emergency situations.

Methods

We retrospectively enrolled 76 PE patients in this study, with 46 patients in the APS-PE group and 30 patients in the non-APS-PE group. We compared differences in demographics, laboratory parameters, and early mortality risk between the two groups. Risk factors for APS-PE were screened using logistic regression analysis. We also developed an early risk score using multivariate analysis weighted points proportional to the β- regression coefficient values and calculated the sensitivity and specificity for APS in PE patients.

Results

In the APS-PE group, we observed a higher proportion of males (43.6 vs. 20%), a higher proportion of low-risk patients (58.7 vs. 10%), lower levels of white blood cells and platelets (PLT), longer activated partial thromboplastin time (APTT), and a slight increase in D-dimer levels. Patients who were triple positive for antiphospholipid antibodies (aPLs) were younger. The APTT gradually increased as the number of positive aPLs increased. The risk factors for APS included male (OR = 5.565, 95% CI 1.176–26.341), decreased PLT (OR = 0.029, 95% CI 0.003–0.330), slightly increased D-dimer (OR = 0.089, 95% CI 0.019–0.426), and prolonged APTT (OR = 4.870, 95% CI 1.189–19.951). The risk score was named MPDA and included male, PLT, D-dimer and APTT, which can predict APS in PE patients with the AUC at 0.888 (95% CI 0.811–0.965).

Conclusion

The risk factors for APS in PE patients are male, low PLT, prolonged APTT and slightly increased D-dimer. The MPDA is a quantitative scoring system which is highly suggestive of APS in PE patients.

Pathogenesis of Two Faces of DVT: New Identity of Venous Thromboembolism as Combined Micro-Macrothrombosis via Unifying Mechanism Based on "Two-Path Unifying Theory" of Hemostasis and "Two-Activation Theory of the Endothelium"

Venous thrombosis includes deep venous thrombosis (DVT), venous thromboembolism (VTE), venous microthrombosis and others. Still, the pathogenesis of each venous thrombosis is not clearly established. Currently, isolated distal DVT and multiple proximal/central DVT are considered to be the same macrothrombotic disease affecting the venous system but with varying degree of clinical expression related to its localization and severity. The genesis of two phenotypes of DVT differing in clinical features and prognostic outcome can be identified by their unique hemostatic mechanisms. Two recently proposed hemostatic theories in vivo have clearly defined the character between "microthrombi" and "macrothrombus" in the vascular system. Phenotypic expression of thrombosis depends upon two major variables: (1) depth of vascular wall damage and (2) extent of the injury affecting the vascular tree system. Vascular wall injury limited to endothelial cells (ECs) in sepsis produces "disseminated" microthrombi, but intravascular injury due to trauma extending from ECs to subendothelial tissue (SET) produces "local" macrothrombus. Pathogen-induced sepsis activates the complement system leading to generalized endotheliopathy, which releases ultra large von Willebrand factor (ULVWF) multimers from ECs and promotes ULVWF path of hemostasis. In the venous system, the activated ULVWF path initiates microthrombogenesis to form platelet-ULVWF complexes, which become "microthrombi strings" that produce venous endotheliopathy-associated vascular microthrombotic disease (vEA-VMTD) and immune thrombocytopenic purpura (ITP)-like syndrome. In the arterial system, endotheliopathy produces arterial EA-VMTD (aEA-VMTD) with "life-threatening" thrombotic thrombocytopenic purpura (TTP)-like syndrome. Typically, vEA-VMTD is "silent" unless complicated by additional local venous vascular injury. A local venous vessel trauma without sepsis produces localized macrothrombosis due to activated ULVWF and tissue factor (TF) paths from damaged ECs and SET, which causes distal DVT with good prognosis. However, if a septic patient with "silent" vEA-VMTD is complicated by additional vascular injury from in-hospital vascular accesses, "venous combined micro-macrothrombosis" may develop as VTE via the unifying mechanism of the "two-path unifying theory" of hemostasis. This paradigm shifting pathogenetic difference between distal DVT and proximal/central DVT calls for a reassessment of current therapeutic approaches.

Osteonecrosis of the Jaws in Patients with Hereditary Thrombophilia/Hypofibrinolysis-From Pathophysiology to Therapeutic Implications

Osteonecrosis of the jaws (ONJ) usually has a clear etiology. Local infection or trauma, radiotherapy and drugs that disrupt the vascular supply or bone turnover in the jaws are its major contributors. The thrombotic occlusion of the bone’s venous outflow that occurs in individuals with hereditary thrombophilia and/or hypofibrinolysis has a less known impact on jaw health and healing capability. Our research provides the most comprehensive, up-to-date and systematized information on the prevalence and significance of hereditary thrombophilia and/or hypofibrinolysis states in ONJ. We found that hereditary prothrombotic abnormalities are common in patients with ONJ refractory to conventional medical and dental treatments. Thrombophilia traits usually coexist with hypofibrinolysis traits. We also found that frequently acquired prothrombotic abnormalities coexist with hereditary ones and enhance their negative effect on the bone. Therefore, we recommend a personalized therapeutic approach that addresses, in particular, the modifiable risk factors of ONJ. Patients will have clear benefits, as they will be relieved of persistent pain and repeated dental procedures.

Concurrent pulmonary arteriovenous malformation and pulmonary embolism causing stroke: a therapeutic dilemma

Background

As pulmonary arteriovenous malformation (PAVM) include a right-to-left shunt, it can be accompanied by fatal complications such as stroke and brain abscess due to paradoxical embolism. A concurrent PAVM and pulmonary embolism (PE) is a rare condition. Therefore, the sequence of management has not been established.

Case presentation

A 62-year-old female patient was transferred to our hospital with a sporadic simple PAVM and concurrent bilateral PE. On chest computed tomography (CT), the acute PE was extended to the segmental pulmonary artery where the feeding artery of PAVM originated. Despite the anticoagulation, the patient complained of left sided weakness on the fifth day of admission, and magnetic resonance imaging revealed an acute infarction in the right lateral thalamus, which was thought to be caused by paradoxical embolism. This situation could lead to a dilemma between the risk of thrombus migration during PAVM embolization and another embolic event due to delayed shunt occlusion during anticoagulation. After a multidisciplinary discussion, a delayed endovascular embolization was performed for PAVM after confirming the complete resolution of PE with 4 months of anticoagulation. The cause of PE in this patient was eventually diagnosed as antiphospholipid syndrome.

Conclusion

The authors reported a rare case of concurrent PAVM and PE that led to an embolic stroke during hospitalization. This patient was managed with delayed endovascular embolization for PAVM after an anticoagulation for PE and stroke. It is thought to be valuable in deciding for a treatment plan for this rare condition.

Role of Direct Oral Anticoagulation Agents as Thromboprophylaxis in Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is an autoimmune disorder that causes venous, arterial and small-vessel thrombosis, pregnancy loss, and premature birth. Cardiac valvular disease, renal thrombotic microangiopathy, thrombocytopenia, hemolytic anemia, and cognitive impairment are some of its other clinical symptoms. Antiphospholipid antibodies cause endothelial cells, monocytes, and platelets to become activated, as well as an increase in tissue factor and thromboxane A2. Complement activation might play a key function in pathogenesis. Long-term oral anticoagulation is used to treat thrombosis, and individuals having arterial episodes should be treated quickly. Patients with systemic lupus erythematosus (SLE), as well as those with solely obstetric antiphospholipid syndrome, should get primary thromboprophylaxis. Obstetric care is based on a combination of medical and obstetric high-risk management, as well as aspirin and heparin therapy. Possible supplementary therapy for this condition is hydroxychloroquine. Statins, rituximab, and novel anticoagulant medicines are all potential future treatments for non-pregnant individuals with antiphospholipid syndrome. We aim to review the role of direct-acting oral anticoagulants (DOACs) as thromboprophylactic drugs in the treatment of APS in this article. The treatment of venous thromboembolism has been transformed by a new class of DOACs. These drugs, such as rivaroxaban, function by inhibiting factor Xa directly. Not only do they have known anticoagulant actions, but they also obviate the need for dosage monitoring and modification, in contrast to warfarin. We conducted an exhaustive literature search of PubMed/MEDLINE and Google Scholar Indexes using the keywords "Antiphospholipid syndrome," "thromboprophylaxis," and "oral anticoagulants" up to September 2021. We found that DOACs have been shown to be non-inferior to warfarin in a variety of anticoagulation situations in a number of high-powered clinical studies. In many hypercoagulable conditions such as APS, DOACs are quickly establishing themselves as first-line therapy. This article is focused on comprehensively reviewing the mechanism of action of DOACs, their role as thromboprophylactic drugs, risks and complications of DOACs, and comparing their efficacy with the standard treatment protocol and warfarin.

Open repair of Superior Vena Cava Syndrome with High Intracranial Pressures using an 'Y' graft

We present the case of a young patient with benign superior vena cava (SVC) syndrome resulting from a complex autoimmune disease. Initial attempts of endovascular repair were unsuccessful. Subsequently, an open bypass of both innominate veins was performed with a cryopreserved femoral arterial 'Y' graft. This was a challenging case due to the combination of complex comorbidities and severe tissue fragility which made the intervention technically difficult. The postoperative recovery was uncomplicated and at 6 weeks follow-up, the patient reported a complete remission of her preoperative symptoms.

Fibrin(ogen) as a Therapeutic Target: Opportunities and Challenges

Fibrinogen is one of the key molecular players in haemostasis. Thrombin-mediated release of fibrinopeptides from fibrinogen converts this soluble protein into a network of fibrin fibres that form a building block for blood clots. Thrombin-activated factor XIII further crosslinks the fibrin fibres and incorporates antifibrinolytic proteins into the network, thus stabilising the clot. The conversion of fibrinogen to fibrin also exposes binding sites for fibrinolytic proteins to limit clot formation and avoid unwanted extension of the fibrin fibres. Altered clot structure and/or incorporation of antifibrinolytic proteins into fibrin networks disturbs the delicate equilibrium between clot formation and lysis, resulting in either unstable clots (predisposing to bleeding events) or persistent clots that are resistant to lysis (increasing risk of thrombosis). In this review, we discuss the factors responsible for alterations in fibrin(ogen) that can modulate clot stability, in turn predisposing to abnormal haemostasis. We also explore the mechanistic pathways that may allow the use of fibrinogen as a potential therapeutic target to treat vascular thrombosis or bleeding disorders. Better understanding of fibrinogen function will help to devise future effective and safe therapies to modulate thrombosis and bleeding risk, while maintaining the fine balance between clot formation and lysis.

No Association of Homocysteine, Anticardiolipin Antibody, and Anti-β2 Glycoprotein I Antibody With Portal Venous System Thrombosis in Liver Cirrhosis

Portal venous system thrombosis (PVST), a common complication of liver cirrhosis, is closely associated with thrombophilia. To explore the association of homocysteine (Hcy), anticardiolipin antibody (aCL), and anti-β2 glycoprotein I antibody (aβ₂GPI), which are possible thrombophilic factors, with PVST in liver cirrhosis. Overall, 654 non-malignant patients (219 with and 435 without liver cirrhosis) admitted between January 2016 and June 2020 were retrospectively evaluated. Presence of PVST, degree of main portal vein (MPV) thrombosis, and clinically significant PVST were identified. Hcy level, hyperhomocysteinemia (HHcy), aCL positivity, and aβ₂GPI positivity were compared according to the presence of liver cirrhosis and PVST. Positive aβ₂GPI was significantly more frequent in patients with liver cirrhosis than those without, but Hcy level and proportions of HHcy and positive aCL were not significantly different between them. PVST could be evaluated in 136 cirrhotic patients. Hcy level [10.57 μmol/L (2.71-56.82) versus 9.97 μmol/L (2.05-53.44); P = 0.796] and proportions of HHcy [4/44 (9.1%) versus 13/81 (16.0%); P = 0.413] and positive aCL [1/23 (4.3%) versus 10/52 (19.2%); P = 0.185] and aβ₂GPI [9/23 (39.1%) versus 21/52 (40.4%); P = 0.919] were not significantly different between cirrhotic patients with and without PVST. There was still no significant association of Hcy level, HHcy, aCL, or aβ₂GPI with PVST based on Child-Pugh classification, MPV thrombosis >50%, and clinically significant PVST. Hcy, aCL, and aβ₂GPI may not be associated with PVST in liver cirrhosis, suggesting that routine screening for Hcy, aCL, and aβ₂GPI should be unnecessary in such patients.

Antiphospholipid syndrome

Antiphospholipid syndrome is one of the more common acquired causes of hypercoagulability. Its major presentations are thrombotic (arterial, venous, or microvascular) and pregnancy morbidity (miscarriages, late intrauterine fetal demise, and severe pre-eclampsia). Classification criteria include 3 different antiphospholipid antibodies: lupus anticoagulant, anticardiolipin, and anti-beta 2 glycoprotein I. Management includes both preventive strategies (low-dose aspirin, hydroxychloroquine) and long-term anticoagulation after thrombosis.

Balancing the Affinity and Pharmacokinetics of Antibodies by Modulating the Size of Charge Patches on Complementarity-Determining Regions

A localized positive charge on IgG (referred to as a "charge patch") shows an adverse effect on pharmacokinetics (PK), so it would seem to be best practice to avoid charge patches during the discovery stage and closely monitor charge interactions during the development process. In certain circumstances, however, charge patches are required for target binding, in which case completely removing charge patches is not feasible. Therefore, quantitative measurement of a charge patch and its impact on PK is critical to the success of therapeutic antibody development. In this article, we generated mutations of a recombinant human antibody (referred to as mAb1) with disrupted charge patches to investigate how charge patches on IgG antibodies impact both target-binding affinity and PK-related factors. We conclude that it is important to modulate the size of the charge patch in order to balance target-binding affinity and PK.

Recommendations of the Spanish Rheumatology Society for Primary Antiphospholipid Syndrome. Part I: Diagnosis, Evaluation and Treatment

OBJECTIVE

The difficulty in diagnosis and the spectrum of clinical manifestations that can determine the choice of treatment for primary antiphospholipid syndrome (APS) has fostered the development of recommendations by the Spanish Society of Rheumatology (SER), based on the best possible evidence. These recommendations can serve as a reference for rheumatologists and other specialists involved in the management of APS.

METHODS

A panel of four rheumatologists, a gynaecologist and a haematologist with expertise in APS was created, previously selected by the SER through an open call or based on professional merits. The stages of the work were: identification of the key areas for drafting the document, analysis and synthesis of the scientific evidence (using the Scottish Intercollegiate Guidelines Network [SIGN] levels of evidence) and formulation of recommendations based on this evidence and formal assessment or reasoned judgement techniques (consensus techniques).

RESULTS

46 recommendations were drawn up, addressing five main areas: diagnosis and evaluation, measurement of primary thromboprophylaxis, treatment for APS or secondary thromboprophylaxis, treatment for obstetric APS and special situations. These recommendations also include the role of novel oral anticoagulants, the problem of recurrences or the key risk factors identified in these subjects. This document reflects the first 21, referring to the areas of: diagnosis, evaluation and treatment of primary APS. The document provides a table of recommendations and treatment algorithms.

CONCLUSIONS

An update of the SER recommendations on APS is presented. This document corresponds to partI, related to diagnosis, evaluation and treatment. These recommendations are considered tools for decision-making for clinicians, taking into consideration both the decision of the physician experienced in APS and the patient. A partII has also been prepared, which addresses aspects related to obstetric SAF and special situations.

Incidence and Risk Factors of Recurrent Venous Thromboembolism after Pulmonary Embolism

Background

Information about the epidemiology of venous thromboembolism (VTE) recurrence in Korea is lacking. The purpose of this study was to investigate VTE cumulative recurrence rates and identify risk factors for VTE recurrence among Korean adults.

Methods

A retrospective cohort study was conducted on adult patients (≥18 years) admitted to a university teaching hospital for pulmonary embolism (PE) from 2005 to 2013. The main outcome of interest was a recurrence of VTE. We used Cox proportional hazard regression analyses to calculate the relative risk of VTE recurrence.

Results

Five-year cumulative incidence of recurrent VTE events was 21.5% (95% confidence interval [CI], 17.7–25.4) in all cases of PE; 17% after provoked and 27% after unprovoked PE. Multivariate analysis showed that body mass index (BMI) of ≥25 (hazard ratio [HR], 2.02; 95% CI, 1.17–3.46; p=0.01) and longer anticoagulation therapy duration (HR, 0.90; 95% CI, 0.84–0.96; p<0.01) were independently associated with risk of VTE recurrence. Risk factors not found to be statistically significant at the <0.05 level included history of VTE (HR, 1.81; 95% CI, 0.84–3.88; p=0.12), unprovoked PE (HR, 1.70; 95% CI, 0.89–3.25; p=0.10), symptomatic deep vein thrombosis (HR, 1.62; 95% CI, 0.89–2.94; p=0.10), and female sex (HR, 1.42; 95% CI, 0.78–2.55; p=0.24). We found that age, history of cancer, and other co-morbidities did not significantly affect the risk of VTE recurrence.

Conclusion

Recurrence of VTE after PE is high. Patients with BMI ≥25 or reduced anticoagulation therapy duration have a higher risk of recurrent VTE.

Pathogenesis of antiphospholipid syndrome: recent insights and emerging concepts

Introduction: Even though our understanding of the antiphospholipid syndrome (APS) has improved tremendously over the last decades, we are still not in a position to replace symptomatic anticoagulation by pathogenesis based causal treatments. Areas covered: Recent years have provided further insights into pathogenetically relevant mechanisms. These include a differentiation of pathogenic subtypes of antiphospholipid antibodies (aPL), novel mechanisms modulating disease activity, for example, extracellular vesicles and microRNA, and novel players in pathogenesis, for example, neutrophils and neutrophil extracellular traps (NETs). Expert commentary: It is evident that aPL induce a proinflammatory and procoagulant state and recent data suggest that different aPL species activate different signaling pathways which sometimes converge into a common cellular response. This implies that presence of more than one aPL species may disproportionally increase the risk for the major manifestations of APS, that is, thrombosis and fetal loss. Further delineation of the pathogenic mechanisms will hopefully provide clues to causal rather than symptomatic treatments of APS.

Clinical implications of systemic lupus erythematosus without and with antiphospholipid syndrome in peri- and postmenopausal age

Antiphospholipid syndrome (APS) in patients with systemic lupus erythematosus (SLE) displays a severe disease sub-phenotype with vascular manifestations ranging from peripheral thrombosis to neurologic and ophthalmic symptoms. The prevalence of morbidities including thrombosis, renal lesions, and cognitive impairment contributes to a higher risk of organ damage and a reduced quality of life in patients. In addition to the clinical heterogeneity, the diagnostic challenge is heightened in elderly patients as APS-related SLE is primarily diagnosed in young females. Many patients reach menopause due to the clinical association of premature menopause and improvements in diagnostic and therapeutic strategies in recent years. Although obstetric morbidity is not a concerning feature of the disease within this age group, a number of manifestations which may contribute to a decreased quality of life are present and must therefore not be disregarded. An improved prognosis derives from successful therapeutic regimens with minimal adverse effects in individual patients. The multifaceted management involves patient evaluation and risk stratification, followed by thromboprophylaxis efforts through the correction of modifiable risk factors, lifestyle recommendations, and pharmacological therapy. This review highlights the role of estradiol in the disease pathogenesis as well as the clinical complications and management of APS-related SLE in perimenopausal and postmenopausal patients.

Subclinical atherosclerosis in asymptomatic carriers of persistent antiphospholipid antibodies positivity: A cross-sectional study

BACKGROUND

Whereas the relationship between subclinical atherosclerosis and antiphospholipid syndrome (APS) has been widely investigated, little is known about subclinical atherosclerosis in asymptomatic carriers with isolated antiphospholipid antibodies positivity (APP).

METHODS

Consecutive APP carriers, APS subjects and matched controls were enrolled. Intima-media thickness of the common carotid artery (CCA-IMT) and of the Bulb (Bulb-IMT) and the prevalence of carotid plaques were assessed in all enrolled subjects.

RESULTS

A total of 104 APP carriers, 221 APS subjects, and 325 matched controls were recruited. As compared with controls, APP carriers and APS subjects showed a higher CCA-IMT (0.90 ± 0.24 vs 0.82 ± 0.12, p = 0.014 and 0.93 ± 0.42 vs 0.82 ± 0.12, p < 0.001, respectively), Bulb-IMT (1.10 ± 0.44 vs 0.95 ± 0.18, p = 0.006 and 1.22 ± 0.68 vs 0.95 ± 0.18, p < 0.001, respectively) and an increased prevalence of carotid plaques (33.7% vs 10.2%, p < 0.001 and 38.5% vs 10.2%, p < 0.001, respectively). These results were confirmed stratifying for antibody isotype, after excluding subjects with systemic lupus erythematosus or other autoimmune diseases and after adjusting for major clinical and demographic variables. CCA-IMT, Bulb-IMT and the prevalence of carotid plaques were higher in subjects with high-titer antibodies and progressively increased for an increasing number of positive antibodies.

CONCLUSIONS

Similar to APS subjects, APP carriers have enhanced subclinical atherosclerosis, a more severe disease being observed in the presence of high-titer antibodies and multiple antibodies positivity. These data argue for a strict monitoring of subclinical signs of atherosclerosis and of cardiovascular risk factors in asymptomatic APP carriers.

Acute diffuse alveolar haemorrhage accompanied by gastrointestinal bleeding in a patient with serious systemic lupus erythematosus: A case report

Systemic lupus erythematosus (SLE) is an autoimmune disease that affects many organs, but multisystem dysfunction is rare. Here, we report a case of a 29-year-old woman who was initially diagnosed with SLE complications including lupus nephritis, lupus encephalopathy, renal hypertension, thrombocytopenia, anaemia and hyperkalaemia. She recovered following treatment with high dose methylprednisolone, intravenous immunoglobulin (IVIG) and continuous renal replacement therapy (CRRT). However, a few days after hospital discharge, she developed gastrointestinal bleeding. Although intensive treatment was administered, the patient deteriorated rapidly and had a progressive decline in oxygen saturation followed by diffuse alveolar haemorrhage and acute left heart failure. Inotropic therapy, mechanical ventilation, blood transfusion, CRRT, antibiotics, intravenous glucocorticoids and other support therapies were initiated and gradually the patient's vital signs stabilized and haemoptysis subsided. This case report emphasises that complications of SLE can occur at any stage of the disease, especially in patients with active SLE. Therefore, it is important for clinicians to be aware of the rare presentations of SLE and its complex management. For multisystem dysfunction, early intensive treatment with high dose corticosteroids and cyclophosphamide is advocated.

Tissue Factor: An Essential Mediator of Hemostasis and Trigger of Thrombosis

Tissue factor (TF) is the high-affinity receptor and cofactor for factor (F)VII/VIIa. The TF-FVIIa complex is the primary initiator of blood coagulation and plays an essential role in hemostasis. TF is expressed on perivascular cells and epithelial cells at organ and body surfaces where it forms a hemostatic barrier. TF also provides additional hemostatic protection to vital organs, such as the brain, lung, and heart. Under pathological conditions, TF can trigger both arterial and venous thrombosis. For instance, atherosclerotic plaques contain high levels of TF on macrophage foam cells and microvesicles that drives thrombus formation after plaque rupture. In sepsis, inducible TF expression on monocytes leads to disseminated intravascular coagulation. In cancer patients, tumors release TF-positive microvesicles into the circulation that may contribute to venous thrombosis. TF also has nonhemostatic roles. For instance, TF-dependent activation of the coagulation cascade generates coagulation proteases, such as FVIIa, FXa, and thrombin, which induce signaling in a variety of cells by cleavage of protease-activated receptors. This review will focus on the roles of TF in protective hemostasis and pathological thrombosis.

Endosomal NADPH-oxidase is critical for induction of the tissue factor gene in monocytes and endothelial cells

Antiphospholipid antibodies (aPL) have been shown to induce tissue factor (TF) expression in monocytes and endothelial cells. However, the underlying signal transduction has been more or less elusive in the past. We have recently shown that aPL enter the lysosomal route in monocytes and dendritic cells, and subsequently activate endosomal NADPH-oxidase (NOX). The generation of superoxide which is dismutated to hydrogen peroxide upregulates the intracellular toll like receptors (TLR) 7 and 8, and leads to robust production of inflammatory cytokines. Here we show that induction of TF by aPL follows the same signaling pathway. Inhibition of endosomal NOX by the anion channel blocker niflumic acid or capture of superoxide by the radical scavenger N-acetylcysteine blocks TF induction by aPL. Furthermore, monocytes from mice deficient in NOX2 do not increase TF surface expression in response to aPL, while cells from mice deficient in glutathione peroxidase- 1 (GPx-1) show an increased response. Unexpectedly, also induction of TF by tumour necrosis factor (TNF)⍺ and lipopolysaccharide (LPS) was strongly dependent on the activation of endosomal NOX. While TNF⍺ apparently depends almost fully on endosomal NOX, signalling of LPS is only partially dependent on this pathway. These data provide further insight into the well-known role of reactive oxygen species in the induction of TF expression and suggest that endosomal signalling may represent a central coordinating point in this process.

Antiphospholipid Syndrome and the Lungs

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterised by recurrent thromboembolic events (arterial or venous) and/or morbidity in pregnancy (fetal loss, premature birth, or recurrent embryonic losses) in the presence of laboratory evidence of antiphospholipid antibodies (aPL). APS is a multisystem disorder. Several lung manifestations may develop in patients with APS including pulmonary embolism (PE)/infarction; thromboembolic and non-thromboembolic pulmonary hypertension (PH) (pulmonary arterial hypertension); pulmonary microthrombosis; acute respiratory distress syndrome associated with catastrophic APS; diffuse alveolar haemorrhage; and pulmonary capillaritis. Postpartum syndrome and cryptogenic fibrosing alveolitis (CFA) can be associated with APS. Pulmonary manifestations are relatively rare but are more likely to be life-threatening compared with other complications of APS. Particularly in the presence of aPL, pulmonary manifestations should be suspected in any systemic lupus erythematosus patient with clinical findings such as chest pain, dyspnoea, tachypnoea, and haemoptysis. Early diagnosis and treatment of pulmonary manifestations in APS are essential for improving mortality rates in patients with this condition. The purpose of this review is to assess current evidence around the diagnosis, prognosis, and management of patients with common and rare pulmonary manifestations of APS.

Polyspecificity of Anti-lipid A Antibodies and Its Relevance to the Development of Autoimmunity

The process of natural selection favours germ-line gene segments that encode CDRs that have the ability to recognize a range of structurally related antigens. This presents an immunological advantage to the host, as it can confer protection against a common pathogen and still cope with new or changing antigens. Cross-reactive and polyspecific antibodies also play a central role in autoimmune responses, and a link has been shown to exist between auto-reactive B cells and certain bacterial infections. Bacterial DNA, lipids, and carbohydrates have been implicated in the progression of autoimmune diseases such as systemic lupus erythematosus. As well, reports of anti-lipid A antibody polyspecificity towards single-stranded DNA together with the observed sequence homology amongst isolated auto- and anti-lipid A antibodies has prompted further study of this phenomenon. Though the lipid A epitope appears cryptic during Gram-negative bacterial infection, there have been several reported instances of lipid A-specific antibodies isolated from human sera, some of which have exhibited polyspecificity for single stranded DNA. In such cases, the breakdown of negative selection through polyspecificity can have the unfortunate consequence of autoimmune disease. This review summarizes current knowledge regarding such antibodies and emphasizes the features of S1-15, A6, and S55-5, anti-lipid A antibodies whose structures were recently determined by X-ray crystallography.

β2-Glycoprotein I-Dependent Anti-Cardiolipin Antibodies Associated With Periodontitis in Patients With Systemic Lupus Erythematosus

BACKGROUND

It was reported that patients with systemic lupus erythematosus (SLE) exhibited increased levels of anticardiolipin (anti-CL) antibodies, a class of antiphospholipid antibodies associated with thrombosis. β2-glycoprotein I (β2GPI) has been considered as the actual target antigen for anti-CL antibodies. This study investigates the association of periodontal infection with anti-CL antibodies in patients with SLE.

METHODS

Fifty-three SLE female patients and 56 healthy female volunteers were recruited in this case-control study. All participants received periodontal examinations. The presence of Porphyromonas gingivalis and Treponema denticola in saliva and plaque samples was detected by polymerase chain reaction. Levels of serum anti-CL and anti-β2GPI antibodies were examined using enzyme-linked immunosorbent assay.

RESULTS

Patients with SLE exhibited more periodontal attachment loss and increased titers of serum anti-CL and anti-β2GPI antibodies compared with healthy controls. Patients with active SLE who harbored P. gingivalis or P. gingivalis together with T. denticola intraorally exhibited significantly higher anti-CL and anti-β2GPI antibodies than those without these bacteria. Anti-CL and anti-β2GPI antibody levels correlated positively with clinical attachment level. Furthermore, increased anti-β2GPI antibody levels were significantly associated with C-reactive protein and erythrocyte sedimentation rate.

CONCLUSIONS

Elevated anti-CL and anti-β2GPI antibody levels were associated with periodontopathic bacteria and periodontal breakdown in patients with SLE. Periodontitis might be a modifiable risk factor for SLE.

Primary Antiphospholipid Syndrome Associated with Pneumonia: A Case Report of a 16-Year-Old Male Patient

Antiphospholipid syndrome (APS) is an autoimmune disease characterised by arterial and/or venous thrombosis and/or recurrent pregnancy loss in the presence of antiphospholipid (APL) antibodies. It is evaluated as APS when it develops associated with other systemic autoimmune diseases or primary APS if there is no concomitant disorder. In this study, we present a case of a 16-year-old male patient with primary APS. The patient was admitted with presumptive diagnosis of pneumonia, but multiple pulmonary thromboembolism (PTE) was observed on computerized tomography (CT) pulmonary angiography. APL antibodies positivity and thrombocytopenia developed in our patient. The patient was evaluated as primary APS since another etiology that could explain PTE was not found. Primary APS is a rare disease in children along with adolescents, compared with APS associated with other systemic autoimmune diseases. We present here a young male patient with primary APS and PTE to contribute to the literature. The patient initially had pneumonia but later developed PTE and thrombocytopenia.

Markers of cardiovascular risk in patients with antiphospholipid syndrome: a meta-analysis of literature studies

Several studies reported on the association between antiphospholipid syndrome (APS) and venous thrombosis. In contrast, little is known about cardiovascular (CV) risk in APS. We performed a meta-analysis on the impact of APS on major markers of CV risk. Studies on the relationship between APS and common carotid artery intima-media thickness (CCA-IMT), internal carotid artery IMT (ICA-IMT), carotid bifurcation IMT (BIF-IMT), prevalence of carotid plaques, flow-mediated dilation (FMD), nitrate-mediated dilation (NMD), and ankle-brachial index (ABI) were systematically searched in PubMed, Web of Science, Scopus, and EMBASE databases. Twenty case-control studies (668 cases, 678 controls) were included. Compared to controls, APS patients showed a higher CCA-IMT (mean difference [MD] 0.11 mm; 95% CI 0.07, 0.14), ICA-IMT (MD 0.08 mm; 95% CI 0.05, 0.11), BIF-IMT (MD 0.09 mm; 95% CI 0.06, 0.12) and a higher frequency of carotid plaques (OR 3.87; 95% CI 1.61, 9.31). Moreover, a lower FMD was found in APS subjects than in controls (MD -4.49%; 95% CI -6.20, -2.78), with no differences in NMD (MD -1.80%; 95% CI -4.01, 0.42). Finally, an increased prevalence of pathological ABI was found in APS patients compared to controls (OR 7.26; 95% CI 1.77, 29.71). Despite heterogeneity among studies, APS appears significantly associated with markers of subclinical atherosclerosis and CV risk. These findings can be useful to plan adequate prevention strategies and therapeutic approaches.

Testosterone, Thrombophilia, and Thrombosis

We describe thrombosis, deep venous thrombosis (DVT) pulmonary embolism (PE; n = 9) and hip-knee osteonecrosis (n = 5) that developed after testosterone therapy (median 11 months) in 14 previously healthy patients (13 men and 1 woman; 13 Caucasian and 1 African American), with no antecedent thrombosis and previously undiagnosed thrombophilia–hypofibrinolysis. Of the 14 patients, 3 were found to be factor V Leiden heterozygotes, 3 had high factor VIII, 3 had plasminogen activator inhibitor 1 4G4G homozygosity, 2 had high factor XI, 2 had high homocysteine, 1 had low antithrombin III, 1 had the lupus anticoagulant, 1 had high anticardiolipin antibody Immunoglobulin G, and 1 had no clotting abnormalities. In 4 men with thrombophilia, DVT-PE recurred when testosterone was continued despite therapeutic international normalized ratio on warfarin. In 60 men on testosterone, 20 (33%) had high estradiol (E2 >42.6 pg/mL). When exogenous testosterone is aromatized to E2, and E2-induced thrombophilia is superimposed on thrombophilia–hypofibrinolysis, thrombosis occurs. The DVT-PE and osteonecrosis after starting testosterone are associated with previously undiagnosed thrombophilia–hypofibrinolysis. Thrombophilia should be ruled out before administration of exogenous testosterone.

Postintervention duration of anticoagulation in venous surgery

For a substantial proportion of patients with deep venous thrombosis (DVT), current treatment strategies are suboptimal and new treatment options are needed. Especially for the group of patients who are at the highest risk for post-thrombotic syndrome, new treatment modalities such as catheter-directed thrombolysis and additional stenting are being investigated. With current clinical studies addressing new technical options, the medical management of patients following these interventions deserves attention. The duration of anticoagulant treatment following surgical or radiological interventions for DVT seems not to be influenced by the presence of a venous stent. According to recent ACCP 2012 guidelines the anticoagulant management in patients who have had any method of thrombus removal performed, the same intensity and duration of anticoagulant therapy as in comparable patients who do not undergo thrombosis removal is recommended (Grade 1B). In the acute phase of thrombosis, irrespective of the technique and whether or not stenting is applied, immediate anticoagulation following the procedure is pertinent to reduce the risk of recurrent thrombosis and thrombus propagation. The long-term treatment duration after venous interventions therefore may be tailored based on common risk factors for recurrent thrombosis and the individual risk for bleeding. Selected thrombophilia factors, d-dimer assessment and residual venous thrombosis provide markers for recurrent DVT. Currently, vitamin K antagonists) provide the main anticoagulants for (prolonged) anticoagulation, while the new oral anticoagulants emerge as promising alternatives. In case prolonged anticoagulation after unprovoked DVT is not indicated, cardiovascular risk management is warranted because of an increased rate of arterial thrombotic events after DVT; aspirin may be indicated as secondary prevention against recurrent thrombosis (while providing primary prevention against arterial thrombosis).

Antiphospholipid antibodies induce translocation of TLR7 and TLR8 to the endosome in human monocytes and plasmacytoid dendritic cells

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by thromboembolic events and/or fetal loss in the presence of antiphospholipid antibodies (aPLs). The mechanisms underlying the pathogenicity of aPLs are still poorly understood. Here we show that 3 human monoclonal aPLs as well as IgG fractions from patients with the APS increase mRNA expression of the intracellular toll-like receptor (TLR) 7 in plasmacytoid dendritic cells and TLR8 in monocytes. Simultaneously they induce the translocation of TLR7 or TLR8 from the endoplasmic reticulum to the endosome. These effects depend on the uptake of aPLs into the endosome, subsequent activation of endosomal NADPH oxidase, and generation of superoxide. As a consequence cells are dramatically sensitized to ligands for TLR7 and TLR8. This observation delineates a novel signal transduction pathway in innate immunity originating from the endosome. Because the overexpression of TLR7 can also be detected in plasmacytoid dendritic cells from patients with the APS ex vivo, our results provide an explanation for proinflammatory and procoagulant effects of aPLs. Because inappropriate expression of TLR7 has been implicated in the development of systemic autoimmunity, these findings may also be relevant for the understanding of autoimmunity.

Patient-derived monoclonal antibodies directed towards beta2 glycoprotein-1 display lupus anticoagulant activity

BACKGROUND

Patients with antiphospholipid syndrome (APS) display a heterogeneous population of antibodies with beta(2) glycoprotein-1 (β(2)GP1) as the major antigen.

OBJECTIVES

We isolated and characterized human mAbs directed against β(2)GP1 from the immune repertoire of APS patients.

METHODS

Variable heavy chain repertoires from B cells from two APS patients with anti-β(2)GP1 antibodies were cloned into the pHEN1-VLrep vector. Constructed full-length IgG antibodies were tested for lupus anticoagulant (LAC) activity and binding to β(2)GP1 and its domains.

RESULTS

Two clones of each patient were selected on the basis of the reactivity of single chain Fv (scFv) fragments displayed on phages towards full-length β(2)GP1 and its isolated domain I. The affinity of selected antibodies for β(2)GP1 was lost when transforming from phages to monovalent scFvs, and was regained when antibodies were constructed as complete IgG, indicating a role for bivalency in binding to β(2)GP1. Both selected clones from patient 2 recognized domain I of β(2)GP1, and for both clones selected from patient 1, binding required the presence of both domain I and domain II. All mAbs displayed LAC activity in both activated partial thromboplastin time-based and dilute Russell's viper venom test-based clotting assays and in thrombin generation.

CONCLUSIONS

In this study, we show successful cloning of patient-derived mAbs that require domain I of β(2)GP1 for binding, and that display LAC activity that is dependent on their affinity for β(2)GP1. These antibodies can help us to gain more insights into the pathogenesis of APS, and may facilitate standardization of APS diagnosis.