The antiphospholipid syndrome

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.

Current Promising Biomarkers and Methods in the Diagnostics of Antiphospholipid Syndrome: A Review

Antiphospholipid syndrome (APS) is a hypercoagulation condition associated with the incidence of heterogenic antiphospholipid antibodies (aPLs), which non-specifically affect hemostasis processes. APS is clinically manifested by recurrent arterial and venous thromboses and reproduction losses. The aPL antibodies, which may induce clinical manifestations of APS, include criteria antibodies anti-cardiolipin, anti-β2-glycoprotein-I, and lupus anticoagulant, but also non-criteria antibodies, for example anti-β2-glycoprotein-I domain I, anti-phosphatidylserine/prothrombin, anti-annexin V, and many others. APS occurs mostly in patients of younger and middle age, most frequently in females. Laboratory diagnostics of APS are quite difficult, as they include a wide spectrum of examining methods, which are based on various principles of detection and are performed using various laboratory techniques. The objective of the review is to describe the current state of potentially examined biomarkers and methods in APS diagnostics. The aforementioned biomarkers are lupus anticoagulant, anti-β2-glycoprotein-I, anti-cardiolipin, anti-β2-glycoprotein-I domain I, anti-phosphatidylserine/prothrombin, anti-β2-glycoprotein-I IgA, anti-cardiolipin IgA, anti-annexin V and II, anti-prothrombin, anti-cardiolipin/vimentin, anti-protein S/protein C, and antibodies against phospholipid antigens for whose diagnostics we may use some of the methods established for a long time and some of the modern methods—the coagulation method for the determination of lupus anticoagulant (LA), enzyme-linked imunosorbent assay (ELISA), chemiluminescence analysis (CLIA), multiplex fluorescence flow immunoassay (MFFIA), fluorescence enzyme immunoassay (EliA), line immunoassay (LIA), multiline dot assay (MLDA), and thin-layer chromatography (TLC). Conclusion: Antibodies against phosphatidylethanolamine, phosphatidic acid, phosphatidylserine, phosphatidylinositol, cardiolipin/vimentin complex, and annexin V are currently the most studied new markers. However, these assays have not been standardized until now, both from the laboratory and clinical point of view. In this review we summarize the evidence of the most studied aPL markers and their potential clinical significance in seronegative APS (SN-APS).

Catastrophic Antiphospholipid Syndrome in Immune Thrombocytopenic Purpura - Beyond Tenuous Concomitance!

Significance of antiphospholipid antibodies in immune thrombocytopenic purpura is debatable and pose a diagnostic and therapeutic dilemma. Catastrophic antiphospholipid syndrome is a rare life-threatening entity, occurring in patients with antiphospholipid syndrome, usually after a triggering event. We describe an adult lady of chronic immune thrombocytopenic purpura (in remission) with antiphospholipid antibodies, who presented with rapidly progressive renal failure and had primary antiphospholipid syndrome nephropathy. The index manuscript titled exemplifies the fact that although the presence of APLA in ITP is known, however, management in the absence of clinical event remains debatable and may carry a future risk of thrombotic event/s mandating close monitoring with a high index of suspicion.

Antiphospholipid antibody syndrome: The difficulties of diagnosis

Antiphospholipid antibody syndrome (APS) is an autoantibody-mediated thrombophilic disorder that causes a hypercoagulable state and can lead to venous thromboembolism, stroke, multiple miscarriages, and other pregnancy complications with the presence of antiphospholipid antibodies. This article reviews screening, diagnosis, and management of APS with a focus on the prevention of long-term complications.

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.

A novel pathway of cellular activation mediated by antiphospholipid antibody-induced extracellular vesicles

BACKGROUND

Elevated levels of endothelial cell (EC)-derived extracellular vesicles (EVs) circulate in patients with antiphospholipid antibodies (APLAs), and APLAs, particularly those against β2 -glycoprotein I (β2 GPI), stimulate EV release from ECs. However, the effects of EC-derived EVs have not been characterized.

OBJECTIVE

To determine the mechanism by which EVs released from ECs by anti-β2 GPI antibodies activate unstimulated ECs.

PATIENTS/METHODS

We used interleukin (IL)-1 receptor inhibitors, small interfering RNA (siRNA) against Toll-like receptors (TLRs) and microRNA (miRNA) profiling to assess the mechanism(s) by which EVs released from ECs exposed to anti-β2 GPI antibodies activated unstimulated ECs.

RESULTS AND CONCLUSIONS

Anti-β2 GPI antibodies caused formation of an EC inflammasome and the release of EVs that were enriched in mature IL-1β, had a distinct miRNA profile, and caused endothelial activation. However, activation was not inhibited by an IL-1β antibody, an IL-1 receptor antagonist, or IL-1 receptor siRNA. EC activation by EVs required IL-1 receptor-associated kinase 4 phosphorylation, and was inhibited by pretreatment of cells with TLR7 siRNA or RNase A, which degrades ssRNA. Profiling of miRNA in EVs released from ECs incubated with β2 GPI and either control IgG or anti-β2 GPI antibodies revealed numerous differences in the content of specific miRNAs, including a significant decrease in mIR126. These observations demonstrate that, although anti-β2 GPI-derived endothelial EVs contain IL-1β, they activate unstimulated ECs through a TLR7-dependent and ssRNA-dependent pathway. Alterations in miRNA content may contribute to the ability of EVs derived from ECs exposed to anti-β2 GPI antibodies to activate unstimulated ECs in an autocrine or paracrine manner.

Primary antiphospholipid syndrome presenting as antiphospholipid syndrome nephropathy: a case report

INTRODUCTION

Primary antiphospholipid syndrome can be a difficult diagnosis in the absence of typical clinical features. We describe an unusual presentation of primary antiphospholipid syndrome mimicking vasculitis for which the only diagnostic clue on initial presentation was antiphospholipid syndrome nephropathy.

CASE PRESENTATION

A 29-year-old Sri Lankan woman presented with features mimicking vasculitis with no obvious clinical features of antiphospholipid syndrome. Classical symptoms of antiphospholipid syndrome only appeared months later. A retrospective analysis showed that the only evidence of antiphospholipid syndrome at her first presentation was antiphospholipid syndrome nephropathy on her renal biopsy.

CONCLUSIONS

A high degree of suspicion of antiphospholipid syndrome is needed when patients present with non-specific vasculitis features. It has a broad clinical impact as antiphospholipid syndrome can present to any clinician with rare manifestations such as nephropathy. This significantly adds to the advancement of knowledge as antiphospholipid syndrome nephropathy should be recognized as a true entity and considered as a classification criteria for antiphospholipid syndrome.

Obstetrical APS: is there a place for hydroxychloroquine to improve the pregnancy outcome?

The use of the conventional APS treatment (the combination of low-dose aspirin and LMWH) dramatically improved the obstetrical prognosis in primary obstetrical APS (OAPS). The persistence of adverse pregnancy outcome raises the need to find other drugs to improve obstetrical outcome. Hydroxychloroquine is widely used in patients with various autoimmune diseases, particularly SLE. Antimalarials have many anti-inflammatory, anti-aggregant and immune-regulatory properties: they inhibit phospholipase activity, stabilize lysosomal membranes, block the production of several pro-inflammatory cytokines and, in addition, impair complement-dependent antigen-antibody reactions. There is ample evidence of protective effects of hydroxychloroquine in OAPS similar to the situation in SLE arising from in vitro studies of pathophysiological working mechanism of hydroxychloroquine. However, the clinical data on the use of hydroxychloroquine in primary APS are lacking and prospective studies are necessary.

The effect of hereditary versus acquired thrombophilia on triple test Down's syndrome screening

OBJECTIVE

To compare the profile of mid gestation triple test serum markers between a cohort of women with history of pregnancy complications with hereditary versus acquired thrombophilia. All were treated with low molecular weight heparin (LMWH) prior to 12 weeks' gestation.

METHODS

A retrospective analysis of second trimester maternal serum screening results for Down syndrome was performed comparing women with inherited versus acquired thrombophilia, all treated with LMWH. The test results were calculated from the combination of triple serum markers and maternal age, and expressed as a multiple of the gestation normal medians (MoM). Results in the study groups were compared with MoM values calculated from our local population (controls).

RESULTS

The median human chorionic gonadotropin (hCG) level was higher only in the acquired thrombophilia group (N = 47) as compared with the control group (1.3 vs. 0.99 MoM, P = 0.005), and not different between the hereditary thrombophilia group (N = 60) (1.1 MoM) and the control group. Alpha-fetoprotein and unconjugated estriol MoMs did not differ between women with inherited (0.95, 0.97), acquired thrombophilia (0.99, 0.90), and controls (1.01, 0.98), respectively.

CONCLUSION

In the interpretation of second trimester maternal serum screening, consideration should be given to the higher hCG maternal serum levels that may occur in women with acquired thrombophilia, even those treated early in pregnancy with LMWH. The higher hCG serum levels may signal the possibility of placental dysfunction, rather than fetal aneuploidy.

Anticardiolipin antibody and anti-beta 2 glycoprotein I antibody assays

Antiphospholipid syndrome (APS) is an autoimmune disease and is a risk factor for a number of clinical manifestations; the classic presentations include fetal death or thrombosis (arterial or venous thromboembolism), in the presence of persistently increased titers of antiphospholipid (aPL) antibodies. The actual cause of APS is unknown but thought to be multifactorial. The disease is characterized by the presence of a heterogenous population of autoantibodies against phospholipid-binding proteins. APS presents either in isolation with no evidence of an underlying disease or in concert with an autoimmune disease such as systemic lupus erythematosus or rheumatoid arthritis. The wide diversity in clinical presentation often causes difficulty in identifying and treating patients and therefore a concise laboratory report containing interpretative comments is required to provide needed guidance to the clinician. For a diagnosis of APS to be made both clinical and laboratory classification criteria must be met. Laboratory testing to identify aPL antibodies includes lupus anticoagulant (liquid-based clotting assays) and immunological solid-phase assays (usually enzyme-linked immunosorbent assay formats) for IgG and/or IgM anticardiolipin (aCL) antibodies and anti-beta 2 glycoprotein I (β2-GPI) antibodies. Other autoantibodies, such as those directed against anionic phospholipids, can also be assayed; however they are not of clinical significance. Participation in a quality assurance program and an in-depth technical and clinical understanding of testing for aPL antibodies are required, as methods are limited by poor robustness, reproducibility, specificity, and standardization. Testing is further complicated by the lack of a "gold standard" laboratory test to diagnose or classify a patient as having APS. This chapter discusses the clinical and laboratory theoretical and technical aspects of aCL and anti-β2GPI antibody assays.

Managing pregnancy in inflammatory rheumatological diseases

Historically, pregnancy in women with many inflammatory rheumatic diseases was not considered safe and was discouraged. Combined care allows these pregnancies to be managed optimally, with the majority of outcomes being favorable. Disease activity at the time of conception and anti-phospholipid antibodies are responsible for most complications. Disease flares, pre-eclampsia, and thrombosis are the main maternal complications, whereas fetal loss and intrauterine growth restriction are the main fetal complications. Antirheumatic drugs used during pregnancy and lactation to control disease activity are corticosteroids, hydroxychloroquine, sulphasalzine, and azathioprine. Vaginal delivery is possible in most circumstances, with cesarean section being reserved for complications.

Chemical synthesis and characterization of wild-type and biotinylated N-terminal domain 1-64 of beta2-glycoprotein I

The antiphospholipid syndrome (APS) is a severe autoimmune disease associated with recurrent thrombosis and fetal loss and characterized by the presence of circulating autoantibodies (aAbs) mainly recognizing the N-terminal domain (DmI) of beta2-glycoprotein I (beta2GpI). To possibly block anti-beta2GpI Abs activity, we synthesized the entire DmI comprising residues 1-64 of beta2GpI by chemical methods. Oxidative disulfide renaturation of DmI was achieved in the presence of reduced and oxidized glutathione. The folded DmI (N-DmI) was purified by RP-HPLC, and its chemical identity and correct disulfide pairing (Cys4-Cys47 and Cys32-Cys60) were established by enzymatic peptide mass fingerprint analysis. The results of the conformational characterization, conducted by far- and near-UV CD and fluorescence spectroscopy, provided strong evidence for the native-like structure of DmI, which is also quite resistant to both Gdn-HCl and thermal denaturation. However, the thermodynamic stability of N-DmI at 37 degrees C was remarkably low, in agreement with the unfolding energetics of small proteins. Of note, aAbs failed to bind to plates coated with N-DmI in direct binding experiments. From ELISA competition experiments with plate-immobilized beta2GpI, a mean IC(50) value of 8.8 microM could be estimated for N-DmI, similar to that of the full-length protein, IC(50)(beta2GpI) = 6.4 microM, whereas the cysteine-reduced and carboxamidomethylated DmI, RC-DmI, failed to bind to anti-beta2GpI Abs. The versatility of chemical synthesis was also exploited to produce an N-terminally biotin-(PEG)(2)-derivative of N-DmI (Biotin-N-DmI) to be possibly used as a new tool in APS diagnosis. Strikingly, Biotin-N-DmI loaded onto a streptavidin-coated plate selectively recognized aAbs from APS patients.

Mechanisms of antiphospholipid antibody-associated pregnancy complications

Women with antiphospholipid syndrome (APS) and antiphospholipid antibodies (aPL) are at high risk for recurrent spontaneous miscarriage and late pregnancy complications, such as preeclampsia and preterm labor. Recent clinical and experimental observations suggest that the pathophysiology of pregnancy failure in patients with APS may involve inflammation at the maternal-fetal interface and disruption of normal trophoblast function and survival, rather than a pro-thrombotic event. While treatment with heparin and aspirin from early pregnancy has been shown to significantly increase the live birth rate in recurrent miscarriage patients with APS, the incidence of severe late pregnancy complications still remains high. This review will discuss what is currently known about the mechanisms by which aPL may compromise pregnancy outcome.