The antiphospholipid syndrome: still an enigma

Fatal attractions that trigger inflammation and drive atherosclerotic disease

BACKGROUND

Atherosclerosis is the salient, underlying cause of cardiovascular diseases, such as arrhythmia, coronary artery disease, cardiomyopathy, pulmonary embolism and myocardial infarction. In recent years, atherosclerosis pathophysiology has evolved from a lipid-based to an inflammation-centric ideology.

METHODS

This narrative review is comprised of review and original articles that were found through the PubMed search engine. The following search terms or amalgamation of terms were used: "cardiovascular disease," "atherosclerosis," "inflammation," "GRP78," "Hsp60," "oxidative low-density lipoproteins," "aldehyde dehydrogenase," "β2-glycoprotein," "lipoprotein lipase A," "human cytomegalovirus." "SARS-CoV-2," "chlamydia pneumonia," "autophagy," "thrombosis" and "therapeutics."

RESULTS

Emerging evidence supports the concept that atherosclerosis is associated with the interaction between cell surface expression of stress response chaperones, including GRP78 and Hsp60, and their respective autoantibodies. Moreover, various other autoantigens and their autoantibodies have displayed a compelling connection with the development of atherosclerosis, including oxidative low-density lipoproteins, aldehyde dehydrogenase, β2-glycoprotein and lipoprotein lipase A. Atherosclerosis progression is also concurrent with viral and bacterial activators of various diseases. This narrative review will focus on the contributions of human cytomegalovirus as well as SARS-CoV-2 and chlamydia pneumonia in atherosclerosis development. Notably, the interaction of an autoantigen with their respective autoantibodies or the presence of a foreign antigen can enhance inflammation development, which leads to atherosclerotic lesion progression.

CONCLUSION

We will highlight and discuss the complex role of the interaction between autoantigens and autoantibodies, and the presence of foreign antigens in the development of atherosclerotic lesions in relationship to pro-inflammatory responses.

High prevalence of thrombophilic risk factors in patients with central retinal artery occlusion

INTRODUCTION

Central retinal artery occlusion (CRAO) is a common cause of blindness and visual morbidity. In the majority of cases, it is related to thrombotic embolism. Nevertheless, the role of inherited or acquired thrombophilic risk factors in CRAO pathogenesis has not been comprehensively studied.

METHODS

In 126 CRAO patients (66 [52.4%] men, median age 55 [range: 18-80] years) and 107 matched controls (56 [52.3%] men, median age 53 [range: 34-78] years) we evaluated classical atherosclerotic risk factors, including serum lipid profile and glucose level, analyzed intima-media complex thickness (IMT) of external carotid arteries, and performed transthoracic echocardiography. Furthermore, we established the prevalence of inherited and acquired thrombophilic risk factors, such as factor V Leiden (FVL) and prothrombin 20210 G/A genetic variants, plasma activity of factor (F) VIII, protein C and antithrombin activity, and free protein S levels. We also assessed the presence of antiphospholipid antibodies (APLA) and evaluated blood homocysteine in all enrolled subjects. Additionally, we estimated the occurrence of Val34Leu polymorphism of the A subunit of coagulation factor XIII (FXIII-A) in both groups as a potential thrombosis-protecting factor.

RESULTS

Among traditional atherosclerotic risk components, obesity/overweight and hypercholesterolemia were the most common in the CRAO group and occurred in 103 (81.7%) and 85 (67.5%) patients, respectively. CRAO patients also had elevated IMT and altered echocardiographic parameters, indicating diastolic cardiac dysfunction. In thrombophilia investigations, at least one laboratory risk factor occurred in 72.2% (n = 91) of CRAO patients, with APLA as the most frequent, detected in 38.1% (n = 48) of them (almost seven times more frequent than in controls, p < 0.001). Deficiencies in protein C activity and free protein S levels were also common in the CRAO group, reported in 17.5% (n = 22) and 19.8% (n = 25) of patients, respectively. Interestingly, among two analyzed prothrombotic genetic variants, only the FVL was related to CRAO, with the allelic frequency 2.4 times more prevalent than in controls (p = 0.044). Finally, the CRAO group was characterized by hyperhomocysteinemia, almost twice as common as in controls (p = 0.026). Antithrombin deficiency, elevated FVIII, and FXIII-A Val34Leu polymorphism were not associated with CRAO.

CONCLUSIONS

Our findings suggest that thrombophilia plays a vital role in the pathogenesis of CRAO. Thus, proper laboratory screening should be considered in the primary and secondary prevention of those episodes, with implementing appropriate therapy as needed.

Successful treatment of lupus anticoagulant hypoprothrombinemia syndrome with rituximab

Lupus anticoagulant-hypoprothrombinemia syndrome (LAHPS) is a rare acquired bleeding disorder secondary to development of antibodies against prothrombin protein, in the presence of antiphospholipid antibodies. We describe the case of a 13-year-old girl who presented with severe menorrhagia and symptomatic anemia. Labs indicated anemia, thrombocytopenia, elevated PT and aPTT, high-titer inhibitor on mixing studies, positive ANA and anti-dsDNA antibodies, along with a triple-positive antiphospholipid antibody panel. Given additional systemic manifestations, systemic lupus erythematosus was diagnosed. High dose steroids and hydroxychloroquine subsequently started. Her clinical course was complicated by femoral deep venous thrombosis and post renal biopsy retroperitoneal hematoma. Further workup revealed low prothrombin level and the diagnosis of lupus anticoagulant hypoprothrombinemia syndrome. In view of suboptimal response to initial immunosuppressive therapy, rituximab was added to her regimen, leading to an improvement in clinical symptoms and resolution of hypoprothrombinemia. She remains recurrence free 5 years from the event.

Hallux Partial Necrosis Associated with Antiphospholipid Syndrome: The Importance of Early Accurate Diagnosis

This study highlights the importance of having a high clinical suspicion of hypercoagulopathy such as antiphospholipid syndrome (APS) in podiatric patients with normal foot pulses and normal standard coagulation tests. APS is an autoimmune disease that is characterized by inflammatory thrombosis in the arteries and veins and obstetric complications such as pregnancy loss. APS usually affects vessels of the lower extremities. We report herein the case of a 46-year-old woman with previous episodes of pre-eclampsia who suffered from partial ischemic necrosis of the hallux of the left foot. After several ischemic episodes of the hallux, with increased risk of toe amputation, the patient was finally diagnosed with APS and treated with specific anticoagulant medication. The patient's symptoms subsided, and toe amputation was prevented. Early accurate diagnosis and appropriate clinical management are critical to providing optimal outcomes and reducing the risk of amputation.

B cells in primary antiphospholipid syndrome: Review and remaining challenges

It is now widely accepted that antiphospholipid antibodies (aPL) have direct pathogenic effects and that B cells, notably through aPL production, play a key role in the development of antiphospholipid syndrome (APS). Recent findings strengthened the implication of B cells with the description of specific B cell phenotype abnormalities and inborn errors of immunity involving B cell signaling in APS patients. In addition, it has been shown in preclinical models that cross-reactivity between APS autoantigens and mimotopes expressed by human gut commensals can lead to B cell tolerance breakdown and are sufficient for APS development. However, B cell targeting therapies are surprisingly not as effective as expected in APS compared to other autoimmune diseases. Elucidation of the B cell tolerance breakdown mechanisms in APS patients may help to develop and guide the use of novel therapeutic agents that target B cells or specific immune pathway.

The antiphospholipid syndrome may induce non-thrombotic internal jugular vein stenosis: two cases report

BACKGROUND

Antiphospholipid syndrome (APS) is associated with a high incidence of thrombotic events, either arterial thrombosis or venous thrombosis. However, APS-related non-thrombotic venous stenosis is rarely reported.

CASE PRESENTATION

This study described two cases of young women with APS-related internal jugular vein stenosis (IJVS) and reviewed current literature on this issue, including clinical features, diagnosis, and treatment.

CONCLUSIONS

IJVS is a rather rare complication of APS. Two cases were reported for the first time that high titer of antiphospholipid antibodies (aPL) might mediate direct vessel wall damage and further induce venous stenosis despite long-term standardized anticoagulation to prevent thrombus formation. Therefore, dynamic monitoring of autoantibodies and concomitant use of anticoagulants and corticosteroids may be necessary to the management of APS and its complications.

Anticardiolipin antibody and anti-β2 glycoprotein I antibody are potential risk markers of ischaemic stroke in Chinese adults

OBJECTIVES

aCL and anti-β2 glycoprotein I antibody (aβ2GPI) are autoantibodies associated with thromboembolic diseases. Here we investigated whether they are correlated with ischaemic cardiovascular disease in a Chinese population.

METHODS

Serum total aCL and aβ2GPI isotypes (IgA, IgG or IgM, separately) were measured in 11 015 Chinese adults. Differences of antibody level between disease and non-disease groups were examined by t-test. The correlation between antibody and ischaemic cardiovascular disease was determined by logistic regression analysis. Performance of risk prediction models employed aCL or aβ2GPI isotypes was evaluated by C statistic, net reclassification improvement index and integrated discrimination improvement.

RESULTS

Total aCL and aβ2GPI isotypes maintained low levels and increased with increasing age except total aCL and aβ2GPI IgG in participants older than 70 years. When distinguishing ischaemic cardiovascular disease by coronary heart disease (CHD) and ischaemic stroke, the stroke group had higher levels of aCL and aβ2GPI isotypes than the non-stroke group, while the CHD group only had a slightly higher aβ2GPI IgG than non-CHD groups. aCL and aβ2GPI were positively correlated with stroke but not with CHD, and improved the performance of conventional risk factors for stroke risk prediction, with C statistic from 0.769 (95% CI 0.744, 0.793) to 0.777 (95% CI 0.754, 0.800) (aβ2GPI IgG, P = 0.0091), and 0.778 (95% CI 0.754, 0.801) (aβ2GPI IgA, P = 0.0793). Stroke risk could be better reclassified by aCL and aβ2GPI, in association with both net reclassification improvement and integrated discrimination improvement statistics (P < 0.05).

CONCLUSION

aCL and aβ2GPI are associated with ischaemic stroke and have added value for stroke risk prediction.

Acute dilated cardiomyopathy in the setting of catastrophic antiphospholipid syndrome and thrombotic microangiopathy: A case series and review

Catastrophic antiphospholipid antibody syndrome (CAPS) is a rare form of antiphospholipid syndrome, an autoimmune condition characterized by vascular thromboses, pregnancy loss, and antiphospholipid (aPL) antibodies. Diagnosis of CAPS relies on thrombosis of at least three different organs systems over 1 week, histopathological evidence of small vessel occlusion, and high aPL antibody titers. In a subset of precipitating circumstances, activation or disruption of endothelial cells in the microvasculature may occur along with cardiomyopathy. We present two cases of CAPS‐associated dilated cardiomyopathy at our institution, focusing on disease management, pathophysiology, and treatment. These patients were of Southeastern Asian descent, raising the possibility of genetic polymorphisms contributing to the development of cardiomyopathy. Both met CAPS criteria and both demonstrated clinicopathologic thrombotic microangiopathy (TMA) and complement activation and developed severe dilated cardiomyopathy with shock. Complement activation plays an important role in the development of CAPS and may be important in the pathogenesis of CAPS‐associated cardiomyopathy. Clinical suspicion for TMA as a pathophysiologic mechanism of unexplained heart failure in CAPS is important and increased awareness of cardiac side effects is necessary so that early treatment can be initiated to halt further cardiac and systemic complications.

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.

Outcomes of Coronary Artery Revascularization Procedures in Patients with Antiphospholipid Syndrome

BACKGROUND

Published data on the outcome of coronary artery revascularization in patients with antiphospholipid syndrome (APS) are limited. Because APS is associated with a high rate of arterial thrombosis, there is concern that coronary revascularization in this group may be complicated by increased need for repeat revascularization. We aimed to determine the incidence and timing of repeat revascularization performed in patients with APS undergoing percutaneous coronary interventions (PCI) or coronary artery bypass grafting (CABG).

METHODS

Our institutional database was queried for individuals (n = 575) testing positive for antiphospholipid antibodies between 2000 and 2012. From this group, 46 patients underwent cardiac catheterization. Charts were reviewed to identify subsequent revascularization procedures.

RESULTS

The study sample consisted of 15 patients (67 ± 11 years, 11 females) who underwent revascularization. All of the study subjects had prior history of arterial (stroke, TIA n = 7) or venous (n = 10) thrombosis. Ten of the subjects had initial revascularization (6 CABG, 4 PCI) at an outside facility, while another five underwent initial PCI at our hospital. Repeat revascularization occurred in five patients (33%) at a median of 6 years (range 4, 13) following the initial revascularization. The median follow-up for patients who did not require repeat revascularization (n = 10) was 10 years (range 2, 15).

CONCLUSION

Amongst patients with APS who underwent CABG or PCI the need for repeat revascularization was infrequent and occurred several years after initial procedure. Based on this small sample size the periprocedural risk associated with coronary artery revascularization in subjects with APS is not prohibitively high.

Presence of Immune Complexes of IgG/IgM Bound to B2-glycoprotein I Is Associated With Non-criteria Clinical Manifestations in Patients With Antiphospholipid Syndrome

Background: Antiphospholipid syndrome (APS) is an acquired autoimmune disorder defined by the presence of both clinical (thromboembolic events or pregnancy morbidity) and laboratory (antiphospholipid antibodies, aPL) manifestations. Despite their importance, several clinical manifestations strongly associated with APS such as livedo reticularis (LR), thrombocytopenia, sicca-ophthalmic(sicca), heart, or neurological manifestations are not included in the APS clinical classification criteria. Circulating immune complexes (CIC) formed by Beta-2-glycoprotein I (B2GPI) and aPL (B2-CIC) have been described and their presence has been related with thrombotic events.

Methods: Cross-sectional and observational cohort study in APS patients with thrombotic symptomatology.

Setting and Participants: Fifty-seven patients from the University Hospital Center Bezanijska Kosa (Belgrade, Serbia) who met the APS classification criteria (35 with primary APS and 22 with APS associated to systemic lupus erythematosus). This study aimed to determine the prevalence of B2-CIC in APS patients and to evaluate their association with clinical manifestations of APS not included in the classification criteria.

Results: B2-CIC prevalence in APS patients was 19.3%. The presence of thrombocytopenia (OR:5.7), livedo reticularis (OR:5.6), sicca (OR:12.6), and leukopenia (OR:5.6) was significantly higher in patients with B2-CIC than in the rest of APS patients. C3 and C4 complement factor levels were significantly lower in B2-CIC positive patients, which suggests a greater consumption of complement. Patients with quadruple aPL positivity (triple aPL-positivity plus the presence of B2-CIC) showed a higher prevalence of thrombocytopenia, leucopenia and LR than those with single/double aPL-positivity. No significant differences were found in the frequencies observed in patients with triple-only vs. single/double aPL-positivity. There were no significant differences between patients with primary APS and lupus-associated APS regarding the prevalence of B2-CIC and outcomes.

Conclusions: Presence of B2-CIC is strongly associated with several non-criteria clinical manifestations related to APS and to higher complement consumption. More studies are required to better understand the clinical significance of B2-CIC.

Obstetric antiphospholipid syndrome

The present clinical and laboratory classification criteria for antiphospholipid syndrome (APS) were established in Sydney, Australia, in 2006. In this review, we focus on the obstetric subset of APS (OAPS), defined by persistent positivity for antiphospholipid antibodies together with either early recurrent pregnancy loss, early fetal death, stillbirth or premature birth <34 gestational weeks due to pre-eclampsia, eclampsia and placental insufficiency. It is important to diagnose these cases since most women suffering from OAPS can, when given appropriate treatment, have successful pregnancies. Furthermore, patients with OAPS may, depending on the antibody profile, be at enhanced risk of thrombotic events later in life. We present an update on the present knowledge of possible underlying pathogenesis, risk factors and risk estimations for adverse pregnancy outcomes before and during pregnancy, current treatment concepts, and long-term outcomes for women with OAPS and their children.

Serum of patients with antiphospholipid syndrome induces adhesion molecules in endothelial cells

OBJECTIVE

The antiphospholipid syndrome (APS) is a systemic auto-immune disease with an unclear pathophysiology. The aim of our study was to understand the development of APS on a cellular level. Therefore, we analyzed the influence of human serum of APS patients on endothelial expression of specific genes and proteins in comparison to a control group.

METHODS

In this study, we analyzed the expression of ICAM-1, VCAM-1, E-selectin and annexin V in primary cultures of human umbilical vein endothelial cells (HUVEC) in response to 10% (v/v) serum of control patients (n = 6), patients with systemic lupus erythematosus (SLE) and no APS (n = 4) or APS patients (n = 9) for 24 h. Total RNA was prepared from confluent endothelial cell layers and mRNA expression of ICAM-1, VCAM-1 and E-selectin was analyzed by reverse transcription polymerase-chain reaction (RT-PCR). The protein expression was determined by Western blot. Serum protein concentrations of soluble forms of adhesion molecules sICAM-1 and sVCAM-1 were quantified by ELISA. Gene expression data were correlated with clinical parameters.

RESULTS

The mRNA expression of ICAM-1 was increased in cells incubated with serum from APS patients (166 ± 22% of control; P = 0.023). Serum of patients with (SLE)/no APS caused a 1.4-fold higher ICAM-1 mRNA level. Western blot analysis showed an increase in protein expression of adhesion molecules ICAM-1 (260 ± 49%; P = 0.011) and VCAM-1 (357 ± 97%; P = 0.023) in cells that were incubated with serum from APS patients. Plasma analysis showed elevated levels of sVCAM-1 in APS patients (189 ± 34%; P = 0.045) compared to the levels measured in the control group. The sVCAM-1 plasma level was correlating with the frequency of abortions.

CONCLUSION

An augmented expression of endothelial adhesion molecules is involved in the pathophysiology of patients with antiphospholipid syndrome.

Association of silent infarcts in sickle cell anemia with decreased annexin A5 resistance

BACKGROUND

Sickle cell anemia (SCA) is characterized by abnormally shaped, adhesive RBCs that interact with white blood cells and the endothelium, leading to chronic hemolysis, vasculopathy and a prothrombotic state. About 10% of subjects with a thrombotic event in the general population will have an associated antiphospholipid (aPL) antibody. One proposed mechanism for the thrombophilic nature of aPL antibodies is the disruption of the potent anticoagulant annexin A5 or Annexin A5 resistance (A5R). We designed a pilot study assessing the presence of aPL antibodies and disruption of A5R in pediatric sickle cell subjects.

METHODS

39 subjects with SCA participated in this study. A5R, DRVVT, anti-β2GP1, anti-β2GP1, anti-phosphatidylserine and anti-cardiolipin antibody assays were performed.

RESULTS

There was a high prevalence of abnormal A5R despite a low prevalence of antiphospholipid antibodies. Multivariate logistic regression analyses showed an association with silent infarcts (p=0.015), lower hemoglobin (p=0.037), older age (p=0.047) and abnormal A5R.

CONCLUSION

We report an association between annexin A5 resistance and presence of silent infarct, low hemoglobin, and older age in a subgroup of SCA subjects. A potential role for perturbed A5R in the pathophysiology of SCA needs to be evaluated further.

Pitfalls in hemostasis exploration, a case report of a girl with Henoch-Schönlein type vasculitis

The adequate performance and correct interpretation of assays for coagulation factor inhibitors play a critical role for the hemostasis laboratory. Both, false positive and false negative inhibitor assays may be reported, leading to erroneous patient’s management. Therefore, we decided to present a case with a spurious image of an exceptionally rare acquired combined haemophilia A, B and C, with severe factor ( F) VIII, IX and XI deficiency, associated with high titre anti - F VIII, IX and XI inhibitors in a 4 years old girl with Henoch-Schönlein type vasculitis. Finally, performing, beside coagulometric methods also antigenic ELISA assays, we had to invalidate the diagnosis. The performance of antiphospholipd antibodies clarified the diagnosis , finally concluding as definite diagnosis Transient Lupus Anticoagulant Syndrome, with decisive impact on therapy and follow-up.

Diagnosis and management of the antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy complications in the presence of persistent antiphospholipid antibodies (APLA). Laboratory diagnosis of APLA depends upon the detection of a lupus anticoagulant, which prolongs phospholipid-dependent anticoagulation tests, and/or anticardiolipin (aCL) and anti-β2-glycoprotein-1 (β2GPI) antibodies. APLA are primarily directed toward phospholipid binding proteins. Pathophysiologic mechanisms underlying thrombosis and pregnancy loss in APS include APLA induced cellular activation, inhibition of natural anticoagulant and fibrinolytic systems, and complement activation, among others. There is a high rate of recurrent thrombosis in APS, especially in triple positive patients (patients with lupus anticoagulant, aCL and anti-β2GPI antibodies), and indefinite anticoagulation with a vitamin K antagonist is the standard of care for thrombotic APS. There is currently insufficient evidence to recommend the routine use of direct oral anticoagulants (DOAC) in thrombotic APS. Aspirin with low molecular weight or unfractionated heparin may reduce the incidence of pregnancy loss in obstetric APS. Recent insights into the pathogenesis of APS have led to the identification of new potential therapeutic interventions, including anti-inflammatory and immunomodulatory therapies. Additional research is needed to better understand the effects of APLA on activation of signaling pathways in vascular cells, to identify more predictive biomarkers that define patients at greatest risk for a first or recurrent APLA-related clinical event, and to determine the safety and efficacy of DOACs and novel anti-inflammatory and immune-modulatory therapies for refractory APS.

Cardiovascular risk factors are major determinants of thrombotic risk in patients with the lupus anticoagulant

BACKGROUND

Patients with the lupus anticoagulant (LA) are at an increased risk of thrombotic events, which in turn increase the risk of death. Understanding the determinants of thrombotic risk in patients with LA may pave the way towards targeted thromboprophylaxis. In the Vienna Lupus Anticoagulant and Thrombosis Study (LATS), we systematically evaluate risk factors for thrombotic events in patients with LA.

METHODS

We followed 150 patients (mean age: 41.3 years, female gender: n = 122 (81.3%), history of thrombosis or pregnancy complications: n = 111 (74.0%)), who tested repeatedly positive for LA until development of thrombosis, death, or censoring. The primary endpoint was a composite of arterial or venous thrombotic events (TEs).

RESULTS

During a median follow-up of 9.5 years (range: 12 days-13.6 years) and 1076 person-years, 32 TEs occurred (arterial: n = 16, venous: n = 16; cumulative 10-year TE incidence: 24.3%). A prolonged lupus-sensitive activated partial thromboplastin time (aPTT-LA) (adjusted subdistribution hazard ratio (SHR) = 2.31, 95% CI: 1.07--5.02), diabetes (adjusted SHR = 4.39, 95% CI: 1.42-13.57), and active smoking (adjusted SHR = 2.31, 95% CI: 1.14-5.02) emerged as independent risk factors of both arterial and venous thrombotic risk. A risk model that includes a prolonged lupus-sensitive aPTT, smoking, and diabetes enabled stratification of LA patients into subgroups with a low, intermediate, and high risk of thrombosis (5-year TE risk of 9.7% (n = 77), 30.9% (n = 51), and 56.8% (n = 22).

CONCLUSIONS

Long-term thrombotic risk in patients with LA is clustered within subjects harboring typical cardiovascular risk factors in addition to a prolonged lupus-sensitive aPTT, whereas patients with none of these risk factors represent a large subgroup with a low risk of thrombosis.

Neutrophil Extracellular Traps, Antiphospholipid Antibodies and Treatment

Neutrophil extracellular traps (NETs) are a network of extracellular fibers, compounds of chromatin, neutrophil DNA and histones, which are covered with antimicrobial enzymes with granular components. Autophagy and the production of reactive oxygen species (ROS) by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase are essential in the formation of NETs. There is increasing evidence that suggests that autoantibodies against beta-2-glycoprotein-1 (B2GP1) induce NETs and enhance thrombosis. Past research on new mechanisms of thrombosis formation in antiphospholipid syndrome (APS) has elucidated the pharmacokinetics of the most common medication in the treatment of the disease.

Antiphospholipid antibodies disappearance in primary antiphospholipid syndrome: Thrombosis recurrence

OBJECTIVE

To evaluate the clinical outcome after aPL (antiphospholipid antibodies) disappearance in primary APS patients.

METHODS

From a cohort of 70 patients with primary APS, we selected patients with positive aPL determinations at onset and ≥2 subsequent negative aPL determinations during the last 5years. To corroborate the immunologic profile, we determined IgG/IgM aCL antibodies, IgG/IgM antiβ2GPl, anti-annexin A5 antibodies and lupus anticoagulant (LA). All patients continued treatment with oral anticoagulants. Clinical data and aPL determinations at onset/after disappearance were obtained.

STATISTICAL ANALYSIS

descriptive statistics and Kaplan-Meier analysis.

RESULTS

We found 24 patients with persistently negative aPL, including the last immunologic profile, 17 females, 7 males, mean age 51.7, disease evolution 16.3years, mean of 4 aPL previous positive determinations. aCL was positive at onset in 87.5%, 29% had double aPL positivity at onset (aCL/LA). Deep venous thrombosis (DVT) and ischemic stroke in 33% and pulmonary embolism in 12.5% were the most frequent manifestations at onset. INR range: 2-3. Time with aPL positive 109.4±80.7months. After 60months of follow-up since aPL disappearance, 45.8% of patients presented thrombosis recurrence, DVT in 9 patients, ischemic stroke in 1, pulmonary artery hypertension in 1. Other non-thrombotic APS manifestations were chronic ulcers in lower extremities and severe thrombocytopenia.

CONCLUSIONS

This study suggest, that in primary APS, persistent negative aPL profile is not an indication to interrupt oral anticoagulant therapy. However, there is a subset of patients that remained asymptomatic. Other studies are necessary in order to elucidate this controversy.

Neutrophil extracellular traps - the dark side of neutrophils

Neutrophil extracellular traps (NETs) were discovered as extracellular strands of decondensed DNA in complex with histones and granule proteins, which were expelled from dying neutrophils to ensnare and kill microbes. NETs are formed during infection in vivo by mechanisms different from those originally described in vitro. Citrullination of histones by peptidyl arginine deiminase 4 (PAD4) is central for NET formation in vivo. NETs may spur formation of autoantibodies and may also serve as scaffolds for thrombosis, thereby providing a link among infection, autoimmunity, and thrombosis. In this review, we present the mechanisms by which NETs are formed and discuss the physiological and pathophysiological consequences of NET formation. We conclude that NETs may be of more importance in autoimmunity and thrombosis than in innate immune defense.