Incidence, pathophysiology, and clinical manifestations of antiphospholipid syndrome

The potential role of molecular mimicry by the anaerobic microbiome in the aetiology of autoimmune disease

Autoimmune diseases are thought to develop as a consequence of various environmental and genetic factors, each of which contributes to dysfunctional immune responses and/or a breakdown in immunological tolerance towards native structures. Molecular mimicry by microbial components is among the environmental factors thought to promote a breakdown in immune tolerance, particularly through the presence of cross-reactive epitopes shared with the human host. While resident members of the microbiome are essential promoters of human health through immunomodulation, defence against pathogenic colonisation and conversion of dietary fibre into nutritional resources for host tissues, there may be an underappreciated role of these microbes in the aetiology and/or progression of autoimmune disease. An increasing number of molecular mimics are being identified amongst the anaerobic microbiota which structurally resemble endogenous components and, in some cases, for example the human ubiquitin mimic of Bacteroides fragilis and DNA methyltransferase of Roseburia intestinalis, have been associated with promoting antibody profiles characteristic of autoimmune diseases. The persistent exposure of molecular mimics from the microbiota to the human immune system is likely to be involved in autoantibody production that contributes to the pathologies associated with immune-mediated inflammatory disorders. Here-in, examples of molecular mimics that have been identified among resident members of the human microbiome and their ability to induce autoimmune disease through cross-reactive autoantibody production are discussed. Improved awareness of the molecular mimics that exist among human colonisers will help elucidate the mechanisms involved in the breakdown of immune tolerance that ultimately lead to chronic inflammation and downstream disease.

The implications of the purinergic signaling throughout pregnancy

Purinergic signaling is a necessary mechanism to trigger or even amplify cell communication. Its ligands, notably adenosine triphosphate (ATP) and adenosine, modulate specific membrane-bound receptors in virtually all human cells. Regardless of the stage of the pregnancy, cellular communication between maternal, placental, and fetal cells is the paramount mechanism to sustain its optimal status. In this review, we describe the crucial role of purinergic signaling on the regulation of the maternal-fetal trophic exchanges, immune control, and endocrine exchanges throughout pregnancy. The nature of the modulation of both ATP and adenosine on the embryo-maternal interface, going through placental invasion until birth delivery depends on the general maternal-fetal health state and consequently on the selective activation of their specific receptors. In addition, an increasing number of studies have been demonstrating the pivotal role of ATP and adenosine in modulating deleterious effects of suboptimal conditions of pregnancy. Here, we discuss the role of purinergic signaling on the balance that coordinates the embryo-maternal exchanges and a promising therapeutic venue in the context of pregnancy disorders.

Imbalance of circulating CTLA4+ follicular helper and follicular regulatory T cells in obstetric antiphospholipid syndrome

Obstetric antiphospholipid syndrome (OAPS) is a systemic autoimmune disease that is characterized clinically by a variety of obstetric manifestations (fetal death and recurrent abortions) and serologically by the presence of antiphospholipid antibodies (aPLs). Whether dysregulation of Follicular helper T (Tfh) and Follicular regulatory T (Tfr) cells contribute to the immunopathogenesis in OAPS is still unknown. We analyzed phenotypic characterizations of circulating Tfh cells and Tfr cells in OAPS patients and healthy individuals. CTLA4(Cytotoxic T lymphocyte antigen 4)⁺ Tfh cells and CTLA4⁺ Tfr cells were declined and CTLA4⁺ Tfr/Tfh ratio and IL-21 were increased in OAPS patients compared with healthy controls. Percentages of CTLA4⁺ Tfh cells and CTLA4⁺ Tfr cells were the lowest in OAPS patients whose antiphospholipid antibodies (aPL) were triple positive. Increased CTLA4⁺ Tfr/Tfh ratio was positively correlated with anti-β2 glycoprotein I (anti-β2GPI) IgM, Complement 4(C4) or IL-21 in OAPS. Increased Th17 subtype and decreased Th1, Th2 subtypes in Tfh cells and Tfr cells, increased effector memory subtype and decreased central memory subtype of Tfh cells and Tfr cells were also observed in OAPS compared with healthy individuals. Our data demonstrated that an imbalance of circulating CTLA4⁺ Tfh cells, and Tfr cells correlates with the immunopathogenesis of OAPS.

Arterial thrombosis in antiphospholipid syndrome (APS): Clinical approach and treatment. A systematic review

Thrombotic Antiphospholipid Syndrome (APS) is a condition affecting young individuals in whom a thromboembolic event occurs in the presence of circulating antiphospholipid antibodies (aPL). An extensive body of literature has covered the most common clinical presentation of the syndrome, venous thromboembolism. Arterial thrombosis in APS, a lesser clinical expression, is less studied. This review will concentrate on the body of literature concerning pathogenesis, clinical presentation and management of arterial thrombosis in APS.

Definition and treatment approach of non-criteria clinical manifestations of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with persistently positive antiphospholipid antibodies. However, in APS, there are several non-thrombotic clinical manifestations such as thrombocytopenia, cardiac valve disease, microthrombotic nephropathy, skin ulcer, or cognitive dysfunction. These non-criteria manifestations are relatively common and usually are non-responsive to anticoagulation. Among the non-criteria manifestations, thrombocytopenia, skin ulcers, migraine, and heart valve lesions are the most frequent manifestations described in APS. Limited data are available on the treatment of non-criteria manifestations of APS, and most therapeutic options are based on case reports or retrospective non-randomized studies. Although there is no consensus on the treatment of non-criteria manifestations of APS, anticoagulant therapy and immunomodulatory drugs could be combined in most patients.

Proteins Involved in the Induction of Procoagulant Activity and Autoimmune Response in Patients With Primary Antiphospholipid Syndrome

The aim of this study was to determine the plasma protein profile of patients with primary antiphospholipid syndrome (PAPS) compared to healthy controls and identify proteins that might be used in the evaluation, diagnosis, and prognosis of this condition. The sample consisted of 14 patients with PAPS and 17 sex- and age-matched controls. Plasma samples were submitted to proteomic analysis (albumin and immunoglobulin G depletion, concentration, digestion, and label-free data-independent mass spectrometry). The software ExpressionE was used to quantify intergroup differences in protein expression. The analysis yielded 65 plasma proteins of which 11 were differentially expressed (9 upregulated and 2 downregulated) in relation to controls. Four of these are known to play a role in pathophysiological mechanisms of thrombosis: fibrinogen α chain, fibrinogen α chain, apolipoprotein C-III, and α-1-glycoprotein-1. Our analysis revealed autoimmune response and the presence of proteins believed to be functionally involved in the induction of procoagulant activity in patients with PAPS. Further studies are necessary to confirm our findings and may eventually lead to the development of significantly more accurate diagnostic tools.

Presumed antiphospholipid syndrome and thrombotic thrombocytopenic purpura: An infrequent association

Antiphospholipid syndrome (APS) is an autoimmune disease that demonstrates antiphospholipid antibodies that cause hypercoagulability and leads to venous and arterial thrombosis. Autoantibodies to a disintegrin-like and metalloprotease with thrombospondin type I motif, member 13 (ADAMTS 13) play a role in the microthrombosis of thrombotic thrombocytopenic purpura in APS patients.

Progesterone receptor expression in fibromuscular dysplasia: A report of two unusual cases

Fibromuscular dysplasia is rarely biopsied. Progesterone receptor expression in myofibroblastic cells is useful for the histopathological evaluation in difficult-to-diagnose cases. Herein, we report two unusual cases of fibromuscular dysplasia in which progesterone receptor expression was shown in vessel sections.

The anti-thrombotic effects of vitamin D and their possible relationship with antiphospholipid syndrome

The importance of the immunomodulatory effects of vitamin D has recently been associated with autoimmune and chronic inflammatory diseases. Vitamin D deficiency has been linked to the development of autoimmune conditions. Antiphospholipid syndrome is an autoimmune disease characterized by thrombotic events and obstetric complications in patients with antiphospholipid antibodies. Current data show that patients with antiphospholipid syndrome have a high prevalence of vitamin D deficiency even without classic risk factors. Several studies have suggested vitamin D may have anti-thrombotic functions. In antiphospholipid syndrome, low vitamin D serum levels have been associated with thrombotic manifestations, suggesting a possible protective role of vitamin D in antiphospholipid syndrome. This literature review presents current evidence on the haemostatic functions of vitamin D and their possible relationship with the clinical manifestations of antiphospholipid syndrome.

CD39 and CD73 activity are protective in a mouse model of antiphospholipid antibody-induced miscarriages

OBJECTIVE

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder of young adults associated with devastating pregnancy complications (recurrent miscarriages, preeclampsia and low birth weight) and vascular complications including thrombosis. The key components implicated in pathogenesis of APS are the complement cascade and tissue factor (TF) activity causing inflammation and coagulation. Purinergic signalling involving catabolism of ATP to adenosine by cell-surface enzymes CD39 and CD73 has anti-inflammatory and anti-thrombotic effects. We studied whether activities of CD39 and CD73 are important in preventing the development of miscarriages in APS.

METHODS

We studied frequency of miscarriages and decidual pathology following passive transfer of human aPL-ab to pregnant wildtype mice, and mice deficient in CD39 and CD73, and also transgenic mice exhibiting 2-3X higher CD39 activity.

RESULTS

aPL-ab infusion in pregnant CD39-or CD73-knockout mice triggers an increase in miscarriages, associated with increased TF expression and complement deposition as well as elevated oxidative stress and pro-inflammatory TNF-α and IL-10 expression within the placental decidua. In contrast, aPL-ab induced miscarriages are prevented in mice over-expressing CD39, with reduced decidual TF expression and C3d deposition, diminished lipid peroxidation (4-hydroxynonenal or 4-HNE positive lipid adducts), and reduced TNF-α expression.

CONCLUSION

We demonstrate a protective role for CD39 in APS and provide rationale for both the development of endothelial cell-targeted soluble CD39 as a novel therapeutic for APS and analysis of perturbations in the purinergic pathway to explain human disease.

A novel 2-stage approach that detects complement activation in patients with antiphospholipid antibody syndrome

INTRODUCTION

The antiphospholipid syndrome (APS) is marked by autoantibodies that recognize anionic phospholipids in a cofactor-dependent manner. A role for complement has been implicated in the pathophysiology, however, elevations of complement activation markers have not been consistently demonstrated in clinical studies. We therefore designed a proof-of-principle study to determine whether complement activation might be detectable in APS by first exposing plasmas to phospholipid vesicles.

METHODS

We examined complement activation markers in patients with APS, non-APS thrombosis, systemic lupus erythematosus, cancer, patients with antiphospholipid antibodies without thrombosis (APL) and healthy controls. Direct measurements of plasma C5a and sC5b-9 levels were compared to levels that were generated in normal serum by phospholipid vesicles that had been pre-incubated with the same plasmas. We then determined the effects of the C5 inhibitor, eculizumab, examined the complement pathways involved, and determined whether the effects could be reproduced with purified IgGs and β2-glycoprotein I (β2GPI).

RESULTS

Plasma levels of C5a and sC5b-9 were higher, but not significantly increased in APS patients compared to healthy controls. In contrast, phospholipid vesicles pre-incubated with APS plasmas generated significantly higher levels than healthy controls and the other groups, except for APL patients. Complement activation was abrogated by addition of eculizumab. The results with substrate sera indicated that the alternative and classical/lectin pathways were involved. The results were reproducible with purified IgGs and β2GPI.

CONCLUSION

This proof-of-principle study confirms a role for complement in APS and opens the possibility of monitoring complement activation by including phospholipid vesicles in assay systems.

Severe Mesenteric Ischemia in a Pregnant Woman with Antiphospholipid Syndrome

The antiphospholipid syndrome (APS), either primary or secondary form, is considered an autoimmune disease with the presence of at least 1 clinical and 1 laboratory abnormalities as defined by the Sydney criteria. Clinical criteria include vascular thrombosis of venous, artery, small vessel in any organ, and recurrent pregnancy pathologies. Mesenteric ischemia is a rare and threatening manifestation of APS. We herein report a case of a 34-year-old pregnant woman referred to our Emergency Room with thoracic and abdominal acute pain. Her past medical history was remarkable for positivity to antiphospholipid antibodies, deep vein thrombosis of the right lower limb, chronic occlusion of celiac trunk, and superior mesenteric artery and recurrent abortions. Imaging revealed acute occlusion of inferior mesenteric artery (IMA). Both a surgical and endovascular thrombectomy were ineffective to obtain durable IMA patency and so the patient underwent antegrade aorta-inferior mesenteric bypass with saphenous vein and resection of an ischemic ileal loop. The medical treatment at discharge was lifelong oral anticoagulant associated with double antiplatelet therapy. To the best of our knowledge, this is the first case reporting a young pregnant woman with APS and mesenteric ischemia submitted to several attempts of revascularization. Aggressive oral anticoagulant and antiplatelet long-term therapy is advised. Moreover, we recommend strict follow-up in those patients in order to early diagnose thrombotic recurrence.

Thrombolytic treatment in a patient with antiphospholipid syndrome : APS developing renal infarction

Antiphospholipid syndrome (APS), a leading entity in acquired thrombophilia, is characterized by recurrent thrombosis, morbidity in pregnancy and presence of antiphospholipid antibodies (APA). Although the etiopathogenesis is unclear, APA against negatively charged phospholipids and phospholipid-protein complexes are held responsible for the clinical picture. In case of acute thrombosis due to APS, thrombolytic therapy is not a commonly administered treatment option. Here, we present a case with acute thrombosis in the left renal artery showing partial response to thrombolytic therapy.