Antiphospholipid syndrome: linking many specialties

Autoantibody Discovery, Assay Development and Adoption: Death Valley, the Sea of Survival and Beyond

Dating to the discovery of the Lupus Erythematosus (LE) cell in 1948, there has been a dramatic growth in the discovery of unique autoantibodies and their cognate targets, all of which has led to the availability and use of autoantibody testing for a broad spectrum of autoimmune diseases. Most studies of the sensitivity, specificity, commutability, and harmonization of autoantibody testing have focused on widely available, commercially developed and agency-certified autoantibody kits. However, this is only a small part of the spectrum of autoantibody tests that are provided through laboratories world-wide. This manuscript will review the wider spectrum of testing by exploring the innovation pathway that begins with autoantibody discovery followed by assessment of clinical relevance, accuracy, validation, and then consideration of regulatory requirements as an approved diagnostic test. Some tests are offered as "Research Use Only (RUO)", some as "Laboratory Developed Tests (LDT)", some enter Health Technology Assessment (HTA) pathways, while others are relegated to a "death valley" of autoantibody discovery and become "orphan" autoantibodies. Those that achieve regulatory approval are further threatened by the business world's "Darwinian Sea of Survival". As one example of the trappings of autoantibody progression or failure, it is reported that more than 200 different autoantibodies have been described in systemic lupus erythematosus (SLE), a small handful (~10%) of these have achieved regulatory approval and are widely available as commercial diagnostic kits, while a few others may be available as RUO or LDT assays. However, the vast majority (90%) are orphaned and languish in an autoantibody 'death valley'. This review proposes that it is important to keep an inventory of these "orphan autoantibodies" in 'death valley' because, with the increasing availability of multi-analyte arrays and artificial intelligence (MAAI), some can be rescued to achieve a useful role in clinical diagnostic especially in light of patient stratification and precision medicine.

Amaurosis fugax, Crohn's Disease and the Anticardiolipin Antibody

Crohn's disease is associated with a hypercoagulable state due to platelet or clotting abnormalities which may be responsible for the thromboembolic episodes seen in this condition. We report the occurrence of anticardiolipin antibodies in a patient with Crohn's disease who presented with Amaurosis fugax and suggest that these antibodies may be a further cause of the hypercoagulable state of Crohn's disease in some patients.

Relationship between redox status and cell fate in immunity and autoimmunity

SIGNIFICANCE

The signaling function of redox molecules is essential for an efficient and proper execution of a large number of cellular processes, contributing to the maintenance of cell homeostasis. Excessive oxidative stress is considered as playing an important role in the pathogenesis of autoimmune diseases by enhancing inflammation and breaking down the immunological tolerance through protein structural modifications that induce the appearance of neo/cryptic epitopes.

RECENT ADVANCES

There is a complex reciprocal relationship between oxidative stress and both apoptosis and autophagy, which is essential to determine cell fate. This is especially relevant in the context of autoimmune disorders in which apoptosis and autophagy play a crucial pathogenic role.

CRITICAL ISSUES

In this review, we describe the latest developments with regard to the involvement of redox molecules in the initiation and progression of autoimmune disorders, focusing on their role in cell fate regulation. We also discuss new therapeutic approaches that target oxidative stress in the treatment of these disorders. The administration of antioxidants is scarcely studied in autoimmunity, and future analyses are needed to assess its beneficial effects in preventing or ameliorating these diseases.

FUTURE DIRECTIONS

Deciphering the intricate relationships between oxidative stress and both apoptosis and autophagy in the context of autoimmunity could be critical in elucidating key pathogenic mechanisms and could lead to novel interventions for the clinical management of autoimmune diseases.

Immune Components of Liver Damage Associated with Connective Tissue Diseases

Autoimmune connective tissue diseases are associated with liver abnormalities and often have overlapping pathological and clinical manifestations. As a result, they can present great clinical challenges and evoke questions about diagnostic criteria for liver diseases. Moreover, discriminating between liver involvement as a manifestation of connective tissue disease and primary liver disease can be challenging since they share a similar immunological mechanism. Most patients with connective tissue diseases exhibit liver test abnormalities that likely result from coexisting, primary liver diseases, such as fatty liver disease, viral hepatitis, primary biliary cirrhosis, autoimmune hepatitis, and drug-related liver toxicity. Liver damage can be progressive, leading to cirrhosis, complications of portal hypertension, and liver-related death, and, therefore, must be accurately identified. In this review, we highlight the challenges facing the diagnosis of liver damage associated with connective tissue disease and identify immune mechanisms involved in liver damage associated with connective tissue diseases.

Dos and don'ts in diagnosing antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an acquired autoimmune thrombotic tendency that is identified by the presence of abnormal antiphospholipid laboratory tests in patients who have a history of vascular thrombosis and/or pregnancy complications including recurrent spontaneous miscarriages and a group of other complications due to placental insufficiency. Diagnostic testing for APS is often problematic because of many misconceptions regarding these empirically derived assays. This chapter is intended to provide hematology-oncology consultants with practical information about the uses and limitations of assays used to diagnose APS.

Anti-phospholipid antibodies and CD5+ B cells in HIV infection

This cross-sectional study evaluates the correlation between anti-phospholipid antibodies and CD5+ B cells in 110 patients infected with HIV-1. There were 89.1% of the patients who had IgG antibodies against cardiolipin and phosphatidylserine. The prevalence of IgM and IgA antibodies was < 22%. AIDS was associated with lower frequencies of IgM antibodies against cardiolipin (P = 0.05) and IgG-antibodies against cardiolipin and phosphatidylserine (P = 0.011). Drug users had higher IgM antibodies against phospholipids than patients from other risk groups (P = 0.02). A history of thromboembolic events was not accompanied by higher levels of anti-phospholipid antibodies (P > 0.2). No correlation between anti-phospholipid antibodies and CD5+ B cells was detected. Percentage part of CD5+ B lymphocytes was elevated in all patients and absolute CD4+ T lymphocyte counts and HIV p24 antigen were inversely correlated. In advanced disease a significant reduction of anti-phospholipid antibodies was contrasted with persistent elevation of CD5+ B lymphocytes. These observations may reflect immunological dysfunction involving apoptosis and endothelial damage rather than polyclonal B cell hyperstimulation. A possible explanation would be that in HIV infection an increased rate of spontaneous apoptosis in peripheral blood lymphocytes is accompanied by functional and structural changes of mitochondria. Therefore, structurally altered mitochondrial phospholipids could serve as antigen to induce specific humoral immune responses.

Exogenous estrogen may exacerbate thrombophilia, impair bone healing and contribute to development of chronic facial pain

A 32 year old white female, in apparently good health, failed to respond to conservative wound care for alveolar osteitis after a routine mandibular first molar extraction. Curettage and biopsy of necrotic alveolar bone from the #30 socket escalated her pain such that hospitalization was necessary for pain management with intravenous morphine. Twelve months prior to admission she had been placed on exogenous estrogen (Premarin, 0.625 mg/day) after a partial oophorectomy. While hospitalized, she was found to have resistance to activated protein C (APCR). Premarin was discontinued. After discharge, weekly changes of an antibiotic impregnated dressing allowed for progressive regeneration of bone and epithelium with gradual reduction in her pain. She was found to be heterozygous for the mutant Factor V Leiden, a heritable factor for increased tendency to form thrombi, so-called thrombophilia. We speculate that the exogenous estrogen administration exacerbated the thrombophilia associated with the Factor V Leiden mutation by compounding the patient's resistance to activated protein C thereby contributing to her development of osteonecrosis and severe alveolar neuralgia.

Prevalence of antibodies to cardiolipin in chronic ITP and reactivity with platelet membranes

Anti-cardiolipin antibodies (ACLA) have been suggested to play a role in the pathogenesis of thrombocytopenia. When sera from 40 patients with chronic idiopathic thrombocytopenic purpura (ITP) were analyzed for ACLA, these autoantibodies were present in 12 (30%). In 4 sera the antibody activity was restricted to the IgG or IgM isotype, respectively, while 4 of the samples contained both IgG and IgM antibodies. To elucidate the interaction between platelets and ACLA, we studied the reactivity of sera from non-ITP patients with ACLA, with fragmented platelet membranes. None of them had a concurrent platelet deficiency, but sera from 8 (67%) of them showed increased IgG-binding to platelet membranes. Absorbtion with cardiolipin reduced membrane binding in 6 (50%). C3 levels were normal, while low C4 values occurred in both groups with significantly lower levels in ACLA-positive patients (p<0.05). Circulating immune complexes (CIC) were common in both groups.

CONCLUSION

The prevalence of ACLA is increased in ITP and sera from non-ITP patients with ACLA react with fragmented platelet membranes. This reactivity is often decreased by absorption with cardiolipin, suggesting that ACLA bind to phospholipid epitopes on platelet membranes.

Recognizing antiphospholipid syndrome. Case report: misdiagnosis delayed treatment

Family physicians should be aware of antiphospholipid syndrome, a rare and recently described disorder, but one that can be treated successfully. Physicians should have a high degree of suspicion in patients with thrombotic symptoms if they are to detect and treat this condition early.

Presence of multiple anti-phospholipid antibody specificities in a pediatric population

Thrombotic related events are thought to be associated with the presence of anti-phospholipid antibodies (APA). However, the association of anti-cardiolipin antibody is much weaker than the association with antibodies to other phospholipids. Much of the literature equates antiphospholipid antibodies and anticardiolipin antibodies because of the relationship of APA and false positive tests for syphilis. However, recently the presence of antibodies to naturally occurring phospholipids other than cardiolipin have been reported. In fact, some investigators report that antibodies to phosphatidylserine appear to correlate more closely to disease processes than anti-cardiolipin antibodies. We describe here the presence of non-anti-cardiolipin antiphospholipid antibodies in a pediatric population that lack anti-cardiolipin antibodies and demonstrate the association of these antibodies with thrombotic disease. Antibodies to phosphatidic acid were the most prevalent and correlated (p < .001) with thrombotic disease and idiopathic thrombocytopenia purpura. The rank order of prevalence of antibodies to phospholipids was phosphatidic acid, phosphatidylglycerol, phosphatidylinosital, phosphatidylserine, cardiolipin and phosphatidylethanolamine. Antiphospholipid antibodies of the three major sera isotypes were present in the positive sera examined. These descriptive findings suggest that the significance of APA other than anti-cardiolipin antibodies in pediatric patients should be further investigated.

Coagulation abnormalities in ischaemic optic neuropathy

The aetiology of non-arteritic ischaemic optic neuropathy (ION) is multifactorial with local anatomical and systemic haemodynamic abnormalities both playing a role. A careful search for treatable vascular disease risk factors is required to allow rational therapy, to optimise the visual prognosis and to allow new insights into pathogenesis. We describe 7 cases in which there was an associated thrombophilic (prothrombotic) state; 4 had deficiencies of the physiological anticoagulants proteins C and S and antithrombin III and 2 had anti-phospholipid antibody (lupus anticoagulant) syndromes. A further patient had reduced levels of the physiological fibrinolytic agent tissue plasminogen activator (t-PA). In 5 patients other risk factors for small vessel occlusive disease were also present, and 4 had recurrent episodes of ION in the same eye. The visual prognosis in these patients may be improved by anticoagulation with warfarin.

Life-threatening right ventricular thrombosis in association with phospholipid antibodies

An 18 year old man presented with cough and dyspnoea caused by pulmonary infarction. A large friable mass of organising thrombus in an anatomically normal right ventricle was identified as an embolic source. The acute illness was associated with raised titres of anticardiolipin antibodies, one of the antiphospholipid group. This thrombus recurred after surgical removal but subsequently was dissipated after treatment with oral corticosteroids and long-term oral anticoagulation.

Amaurosis fugax, Crohn's disease and the anticardiolipin antibody

Crohn's disease is associated with a hypercoagulable state due to platelet or clotting abnormalities which may be responsible for the thromboembolic episodes seen in this condition. We report the occurrence of anticardiolipin antibodies in a patient with Crohn's disease who presented with Amaurosis fugax and suggest that these antibodies may be a further cause of the hypercoagulable state of Crohn's disease in some patients.

Antiphospholipid syndrome: the reality and implications

A case is made for the existence of a primary antiphospholipid antibody syndrome. This clinical entity can be characterized as including an elevation in titers of antibodies to negatively charged phospholipids, hypercoagulation, thrombocytopenia, and recurrent fetal loss. With further elucidation, the systemic pathologic roles of antiphospholipid antibodies should emerge.

Prospective study of fluctuations of lupus anticoagulant activity and anticardiolipin antibody titre in patients with systemic lupus erythematosus

Fluctuations of lupus anticoagulant activity and anticardiolipin antibody titres were studied in 53 patients with systemic lupus erythematosus (SLE). The median study time was 26 months with a median number of 12 samples. Lupus anticoagulant was measured by the kaolin clotting time (KCT) and dilute Russell viper venom time (dRVVT) assays; anticardiolipin antibodies were assayed by an enzyme linked immunosorbent assay (ELISA). Normal and increased KCTs or dRVVTs were seen during follow up in 13 and 12 patients, respectively. IgG anticardiolipin antibodies changed from negative to positive or positive to negative in 26 patients and IgM anticardiolipin antibodies in 16 patients. Disease activity and treatment with prednisone could account for these fluctuations in the kaolin clotting time (KCT) in 7 of 13 patients and in the dRVVT in 2 of 12 patients. Whole group analysis showed that the KCT, dRVVT, and IgM anticardiolipin antibodies were not associated with disease activity, in contrast with IgG anticardiolipin antibodies. During treatment with prednisone normal KCT and dRVVT results were obtained more easily than normal anticardiolipin antibody levels. It is recommended that lupus patients should not be classified as antiphospholipid antibody positive or negative on the basis of only one sample.

A new player in the antiphospholipid syndrome: the beta 2 glycoprotein I cofactor

The study of antiphospholipid (aPL) antibodies has been greatly developed in recent years and conclusive evidence now exists concerning the correlation between aPL and clinical signs such as thrombosis, thrombocytopenia, abortion, and fetal loss. Several hypotheses have been put forward concerning the pathogenic mechanism of aPL, but none has received final confirmation from experimental data. Many studies have been devoted to characterizing the antigens recognized by the different aPL autoantibodies and to a cofactor involved in the binding of autoantibodies and phospholipids; this cofactor has been identified as an apolipoprotein, the beta 2 glycoprotein I (beta 2GPI) or APO-H. Direct evidence now exists which suggests that both the beta 2GPI and the phospholipid comprise the epitope to which aPL are directed. On the other hand anti-beta 2GPI antibodies have been identified in sera of patients suffering from SLE and primary Antiphospholipid Syndrome. beta 2GPI is normally present in human plasma/serum and possesses numerous inhibitory functions in multiple coagulation pathways. The amino acid sequence of beta 2GPI has been identified and found to consist of five repeating units that belong to the complement control protein (CCP) superfamily. This development of knowledge related to aPL has followed three steps respectively: 1. the standardization of the techniques of detection: 2. identification of the clinical signs related to the autoantibodies: and finally 3. the discovery of a new player, the beta 2GPI cofactor.

Addison's disease, hypertension, renal and hepatic microthrombosis in 'primary' antiphospholipid syndrome

We describe a 14 year old boy with antiphospholipid syndrome who initially presented at the age of 10 with recurrent loin pain, fever, weight loss, leucocytosis, thrombocytopenia, hypertension and haematuria. He had primary adrenal insufficiency with bilaterally enlarged adrenals on computed tomographic (CT) scan consistent with adrenal infarction. Renal and liver biopsies showed microthrombi in the glomerular capillaries and hepatic sinusoids respectively. The case is unusual in that hypertension rather than hypotension was dominant and a CT scan was consistent with bilateral adrenal infarction without haemorrhage. He represented with evidence of persistent hypertension with glomerulosclerosis and glomerular microthrombi on repeat renal biopsy. He continues to have permanent adrenal insufficiency with complete atrophy of his adrenals.

Cofactor dependent and cofactor independent anticardiolipin antibodies

Two distinct types of anticardiolipin antibodies are described, one of which requires the presence of a serum factor (cofactor) to bind cardiolipin in ELISA and liposome affinity systems. The second type does not require this cofactor. The requirement of a cofactor for the binding of some but not all anticardiolipin antibodies provides an explanation for the confounding variability of the results of assays for these antibodies. It also explains why blocking agents such as BSA and gelatin do not produce consistent results in this assay.

Antiendothelial cell antibodies in patients with the antiphospholipid syndrome

Antiendothelial cell antibodies (AECA) have been detected in 20 out of 30 patients (67%) with thrombosis associated with antiphospholipid antibodies. Seven patients had systemic lupus erythematosus and 13 had the "primary" antiphospholipid syndrome. Seven patients had both IgG and IgM AECA, 9 had IgG AECA only, and 4 had only IgM AECA. None of 30 control patients with thrombotic events not related to antiphospholipid antibodies had a positive titre of AECA (P less than 0.001). No correlation between AECA, antinuclear antibodies, anti-dsDNA antibodies, anti-neutrophil cytoplasm antibodies, precipitating antibodies to soluble nuclear and cytoplasmic antigens or complement components was found. The possible role of these AECA in the pathogenesis of thrombotic events is discussed.

Immunology and clinical importance of antiphospholipid antibodies

Having reviewed the literature on the association of aPL antibodies with clinical manifestations, it is clear that this group of autoantibodies are of considerable importance. The presence of aPL antibodies in some but not all individuals confers a risk of a clinical syndrome characterized by recurrent arterial or venous thrombosis, thrombocytopenia, hemolytic anemia, or positive Coombs' test, and in females, recurrent idiopathic fetal loss. In SLE, the risk is approximately 40%, compared with a risk of 15% in the absence of aPL antibodies. However, only one half of persons possessing these antibodies have SLE, and overall the risk is around 30%. In some circumstances, such as in chlorpromazine or infection-associated aPL antibodies, there appears to be no increased risk. At the other end of the spectrum are seen patients whose only clinical manifestations comprise features of this clinical syndrome, and this entity has been designated the primary antiphospholipid syndrome (PAPS). aPL antibodies are also important because they are not uncommon. They have been found frequently in women with idiopathic recurrent fetal loss (30%), in non-autoimmune patients with ischemic heart disease (20%), or venous thrombosis (up to 30%), or stroke (4-47%), and in chronic immune thrombocytopenia (30%). These autoantibodies can be detected using sensitive solid-phase immunoassays employing the CL antigen, or in appropriate coagulation tests to detect LA activity. These assays are simple to perform but require care in selection of the best test and in interpretation of results. Current tests do not distinguish between those persons at risk of the clinical events and those not at risk. Detection of specific isotypes (especially IgG) and antibody level may aid in such a designation. Treatment of aPL antibody-associated syndromes remains a controversial subject. Since thromboses are associated with significant morbidity and potential mortality, there is a good argument for long-term preventive antithrombotic therapy, at least for as long as the antibodies are detectable, in those patients in whom clinical complications have previously occurred. It is not generally recommended that this treatment be offered to individuals in whom aPL antibodies are detected but who have not suffered previous thromboses, since the risk of such events does not appear to be equal within a group of aPL antibody-positive persons. This particularly applies to pregnant women, since live births and uncomplicated pregnancies are observed regularly in the presence of aPL antibodies without specific treatment. A previous history of at least one unexplained, late fetal loss is considered a prerequisite before intervention in subsequent pregnancies.(ABSTRACT TRUNCATED AT 400 WORDS)

Vaso-occlusive retinopathy in the primary anti-phospholipid antibody syndrome

We report two patients with contrasting patterns of retinal vascular occlusion associated with the primary anti-phospholipid antibody syndrome. The immuno-pathological features and clinical associations are discussed. This condition is of interest to ophthalmologists because of its association with thrombosis in the eye, brain and elsewhere and because it provides new insights into the pathogenesis of retinal vascular disease in young patients.

Recurrent disseminated intravascular coagulation and fulminant intra hepatic thrombosis in a patient with the anti-phospholipid syndrome

We describe a patient with the lupus anti-coagulant who had recurrent episodes, over a 2 year period, of a severe and disseminated intravascular coagulopathy. This patient also had positive serological assays for syphilis and anti-cardiolipin antibodies. Associated with the coagulopathy were co-expressed episodes of liver disease, ultimately terminating in fulminant liver failure. At autopsy the features were characteristic of the Budd-Chiari syndrome. This is the first report to document how consumptive coagulopathy may present as a dominant feature of the anti-phospholipid syndrome. It also clearly describes an immune mediated thrombotic mechanism as a cause of hepatic veno-occlusive disorders. Furthermore, this case highlights the varied clinical spectrum of the anti-phospholipid syndrome and suggests that a high index of suspicion is required to ensure its diagnosis.