Signaling Through FcγRIIA and the C5a-C5aR Pathway Mediate Platelet Hyperactivation in COVID-19

Patients with COVID-19 present with a wide variety of clinical manifestations. Thromboembolic events constitute a significant cause of morbidity and mortality in patients infected with SARS-CoV-2. Severe COVID-19 has been associated with hyperinflammation and pre-existing cardiovascular disease. Platelets are important mediators and sensors of inflammation and are directly affected by cardiovascular stressors. In this report, we found that platelets from severely ill, hospitalized COVID-19 patients exhibited higher basal levels of activation measured by P-selectin surface expression and had poor functional reserve upon in vitro stimulation. To investigate this question in more detail, we developed an assay to assess the capacity of plasma from COVID-19 patients to activate platelets from healthy donors. Platelet activation was a common feature of plasma from COVID-19 patients and correlated with key measures of clinical outcome including kidney and liver injury, and APACHEIII scores. Further, we identified ferritin as a pivotal clinical marker associated with platelet hyperactivation. The COVID-19 plasma-mediated effect on control platelets was highest for patients that subsequently developed inpatient thrombotic events. Proteomic analysis of plasma from COVID-19 patients identified key mediators of inflammation and cardiovascular disease that positively correlated with in vitro platelet activation. Mechanistically, blocking the signaling of the FcγRIIa-Syk and C5a-C5aR pathways on platelets, using antibody-mediated neutralization, IgG depletion or the Syk inhibitor fostamatinib, reversed this hyperactivity driven by COVID-19 plasma and prevented platelet aggregation in endothelial microfluidic chamber conditions. These data identified these potentially actionable pathways as central for platelet activation and/or vascular complications and clinical outcomes in COVID-19 patients. In conclusion, we reveal a key role of platelet-mediated immunothrombosis in COVID-19 and identify distinct, clinically relevant, targetable signaling pathways that mediate this effect.

Neutrophil-Dependent Immunity During Pulmonary Infections and Inflammations

Rapid recruitment of neutrophils to an inflamed site is one of the hallmarks of an effective host defense mechanism. The main pathway through which this happens is by the innate immune response. Neutrophils, which play an important part in innate immune defense, migrate into lungs through the modulation actions of chemokines to execute a variety of pro-inflammatory functions. Despite the importance of chemokines in host immunity, little has been discussed on their roles in host immunity. A holistic understanding of neutrophil recruitment, pattern recognition pathways, the roles of chemokines and the pathophysiological roles of neutrophils in host immunity may allow for new approaches in the treatment of infectious and inflammatory disease of the lung. Herein, this review aims at highlighting some of the developments in lung neutrophil-immunity by focusing on the functions and roles of CXC/CC chemokines and pattern recognition receptors in neutrophil immunity during pulmonary inflammations. The pathophysiological roles of neutrophils in COVID-19 and thromboembolism have also been summarized. We finally summarized various neutrophil biomarkers that can be utilized as prognostic molecules in pulmonary inflammations and discussed various neutrophil-targeted therapies for neutrophil-driven pulmonary inflammatory diseases.

Inhibition of hypoxia inducible factor 1 by YC-1 attenuates tissue plasminogen activator induced hemorrhagic transformation by suppressing HMGB1/TLR4/NF-κB mediated neutrophil infiltration in thromboembolic stroke rats

Hemorrhagic transformation (HT) is a frequent complication of ischemic stroke after thrombolytic therapy and seriously affects the prognosis of stroke. Due to the limited therapeutic window and hemorrhagic complications, tissue plasminogen activator (t-PA) is underutilized in acute ischemic stroke. Currently, there are no clinically effective drugs to decrease the incidence of t-PA-induced HT. Hypoxia-inducible factor 1 (HIF-1) is an important transcription factor that maintains oxygen homeostasis and mediates neuroinflammation under hypoxia. However, the effect of HIF-1 on t-PA-induced HT is not clear. The aim of this study was to investigate the role of HIF-1 in t-PA-induced HT by applying YC-1, an inhibitor of HIF-1. In the present study, we found that HIF-1 expression was significantly increased in ischemic brain tissue after delayed t-PA treatment and was mainly localized in neurons and endothelial cells. Inhibition of HIF-1 by YC-1 improved infarct volume and neurological deficits. YC-1 inhibited matrix metalloproteinase protein expression, increased tight junction protein expression, and ameliorated BBB disruption and the occurrence of HT. Furthermore, YC-1 suppressed the release of inflammatory factors, neutrophil infiltration and the activation of the HMGB1/TLR4/NF-κB signaling pathway. These results demonstrated that inhibition of HIF-1 could protect BBB integrity by suppressing HMGB1/TLR4/NF-κB-mediated neutrophil infiltration, thereby reducing the risk of t-PA-induced HT. Thus, HIF-1 may be a potential therapeutic target for t-PA-induced HT.

Fatal intracardiac and pulmonary arterial thromboembolic damage following ABO-incompatible living donor liver transplantation for autoimmune hepatitis: A case report

RATIONALE

We present the case of a patient with autoimmune hepatitis who suffered fatal intracardiac and pulmonary arterial thromboembolic complications after ABO-incompatible living donor liver transplantation (ABOi LDLT) with splenectomy.

PATIENT CONCERNS

A 46-year-old female (blood type B+) with autoimmune hepatitis and hepatitis B carrier status underwent elective ABOi LDLT. The donor liver was from a 51-year-old male living donor (blood type A+). A splenectomy was performed without bleeding complications. Intraoperatively, the patients hemodynamic condition was acceptable, with no evidence of thromboembolism on transesophageal echocardiography (TEE).

DIAGNOSIS

Postoperatively, her platelet count increased from 15.0 to 263.0 (× 109/L) and thromboelastographic parameters indicated hypercoagulable state. She suffered acute circulatory collapse, respiratory distress and, eventually, a decline in mental status. The attending physicians in the intensive care unit (ICU) immediately performed resuscitation.

INTERVENTIONS

The patient underwent emergency exploratory surgery. Intraoperatively, hypotension, bradycardia and arrhythmia developed, together with high central venous pressure. Assessment of cardiac structure and function using rescue TEE incidentally identified multiple, huge thromboembolic clots in the cardiac chambers; therefore, the patient underwent cardiac thromboembolectomy, including cardiopulmonary bypass with hypothermia therapy.

OUTCOMES

Due to severe cardiac and respiratory distress, the patient required venoarterial extracorporeal membrane oxygenation (VAECMO) in the operating room and ICU. Despite continuous resuscitation in the ICU and maintenance of VAECMO, she suffered severe hypotension and massive bleeding that eventually led to death.

LESSONS

In patients with autoimmune hepatitis, risk factors for thromboembolism should be rigorously controlled during the peak period of reactive thrombocytosis after ABOi LDLT with splenectomy.

Is COVID-19 associated thrombosis caused by overactivation of the complement cascade? A literature review

Severe acute respiratory syndrome coronavirus 2 is responsible for the current COVID-19 pandemic resulting in an escalating number of cases and fatalities worldwide. Preliminary evidence from these patients, as well as past coronavirus epidemics, indicates that those infected suffer from disproportionate complement activation as well as excessive coagulation, leading to thrombotic complications and poor outcome. In non-coronavirus cohorts, evidence has accumulated of an interaction between the complement and coagulation systems, with one amplifying activation of the other. A pressing question is therefore if COVID-19 associated thrombosis could be caused by overactivation of the complement cascade? In this review, we summarize the literature on thrombotic complications in COVID-19, complement activation in coronavirus infections, and the crosstalk between the complement and coagulation systems. We demonstrate how the complement system is able to activate the coagulation cascade and platelets, inhibit fibrinolysis and stimulate endothelial cells. We also describe how these interactions see clinical relevance in several disorders where overactive complement results in a prothrombotic clinical presentation, and how it could be clinically relevant in COVID-19.

The potential role of microvascular pathology in the neurological manifestations of coronavirus infection

Human coronaviruses are highly pathogenic viruses that pose a serious threat to human health. Examples include the severe acute respiratory syndrome outbreak of 2003 (SARS-CoV-1), the Middle East Respiratory Syndrome (MERS-CoV) outbreak of 2012, and the current SARS-CoV-2 (COVID-19) pandemic. Herein, we review the neurological manifestations of coronaviruses and discuss the potential pathogenic role of blood-brain barrier dysfunction. We present the hypothesis that pre-existing vascular damage (due to aging, cardiovascular disease, diabetes, hypertension or other conditions) facilitates infiltration of the virus into the central nervous system (CNS), increasing neuro-inflammation and the likelihood of neurological symptoms. We also discuss the role of a neuroinflammatory cytokine profile in both blood-brain barrier dysfunction and macrovascular disease (e.g. ischemic stroke and thromboembolism). Future studies are needed to better understand the involvement of the microvasculature in coronavirus neuropathology, and to test the diagnostic potential of minimally-invasive screening tools (e.g. serum biomarkers, fluorescein retinal angiography and dynamic-contrast MRI).

Immune Responses and Anti-inflammatory Strategies in a Clinically Relevant Model of Thromboembolic Ischemic Stroke with Reperfusion

The poor clinical relevance of experimental models of stroke contributes to the translational failure between preclinical and clinical studies testing anti-inflammatory molecules for ischemic stroke. Here, we (i) describe the time course of inflammatory responses triggered by a thromboembolic model of ischemic stroke and (ii) we examine the efficacy of two clinically tested anti-inflammatory drugs: Minocycline or anti-CD49d antibodies (tested in stroke patients as Natalizumab) administered early (1 h) or late (48 h) after stroke onset. Radiological (lesion volume) and neurological (grip test) outcomes were evaluated at 24 h and 5 days after stroke. Immune cell responses peaked 48 h after stroke onset. Myeloid cells (microglia/macrophages, dendritic cells, and neutrophils) were already increased 24 h after stroke onset, peaked at 48 h, and remained increased-although to a lesser extent-5 days after stroke onset. CD8⁺ and CD4⁺ T-lymphocytes infiltrated the ipsilateral hemisphere later on (only from 48 h). These responses occurred together with a progressive blood-brain barrier leakage at the lesion site, starting 24 h after stroke onset. Lesion volume was maximal 24-48 h after stroke onset. Minocycline reduced both lesion volume and neurological deficit only when administered early after stroke onset. The blockade of leukocyte infiltration by anti-CD49d had no impact on lesion volume or long-term neurological deficit, independently of the timing of treatment. Our data are in accordance with the results of previous clinical reports on the use of Minocycline and Natalizumab on ischemic stroke. We thus propose the use of this clinically relevant model of thromboembolic stroke with recanalization for future testing of anti-inflammatory strategies for stroke.

The FcγRIIa polymorphism R/H131, autoantibodies against the platelet receptors GPIbα and FcγRIIa and a risk for thromboembolism in lupus anticoagulant patients

There is a clear propensity of individuals with lupus anticoagulant (LA) for thromboembolic disease (TE). Yet, it is not clear how individuals at risk for TE can be differentiated from those who are not. The FcγRIIa receptor is the only Fc receptor expressed by platelets. As platelets can be activated via this receptor, we have compared gene frequencies of the FcγRIIa polymorphism R/H131 in 46 and 27 patients with (LA/TE+) and without TE (LA/TE-), respectively, in an exploratory study. Furthermore, we investigated the presence of autoantibodies against FcγRIIa and/or GPIbα, which is in close proximity to the FcγRIIa and interacts with it functionally, and a possible linkage of antibody formation to HLA class II alleles. The FcγRIIa-R/R131 genotype was significantly less frequent in patients with LA compared to controls (p< 0.025). These findings were due to an increased frequency of heterozygous patients in the LA/TE+ cohort (odds ratio 6.76, 95% confidence interval 1.55 – 62.03, p< 0.008). For the first time, heterozygosity, rather than homozygosity, can be linked to disease, which may be explained by the dual function of the FcγRIIa, namely binding of antibodies to platelets and thereby their activation, and, on the other hand, clearance of antibody coated platelets by the phagocyte system. There was no correlation between the presence of anti-FcγRIIa or anti GPIbα autoantibodies and the FcγRIIa -R/H131 polymorphism, nor the incidence of TE, nor HLA class II alleles.

Incidence of thromboembolic events in asymptomatic carriers of IgA anti ß2 glycoprotein-I antibodies

BACKGROUND

The antiphospholipid syndrome (APS) is defined by simultaneous presence of vascular clinical events and antiphospholipid antibodies (aPL). The aPL considered as diagnostics are lupus anticoagulant and antibodies anticardiolipin (aCL) and anti-ß2 glycoprotein-I (aB2GP1). During recent years, IgA aB2GP1 antibodies have been associated with thrombotic events both in patients positive, and mainly negative for other aPL, however its value as a pro-thrombotic risk-factor in asymptomatic patients has not been well defined.

OBJECTIVE

To test the role of IgA anti B2GP1 as a risk factor for the development of APS-events (thrombosis or pregnancy morbidity) in asymptomatic population with a 5-year follow-up.

METHODS

244 patients isolated positive for anti-beta2-glycoprotein I IgA (Group-1 study) and 221 negative patients (Group-2 control) were studied. All the patients were negative for IgG and IgM aCL.

RESULTS

During the follow-up, 45 patients (9.7%) had APS-events, 38 positive for IgA-aB2GP1 and 7 negative (15.6% vs 3.2%, p<0.001). The incidence rate of APS-events was 3.1% per year in IgA-aB2GP1 positive patients and 0.6% per year in the control group. Arterial thrombosis were the most frequent APS-events (N = 25, 55%) and were mainly observed in Group-1 patients (21 vs 4, p = 0.001). Multivariate analysis were shown as independent risk-factors for the development of APS-events, age, sex (men) and presence of IgA-aB2GP1 (odds ratio 5.25, 95% CI 2.24 to 12.32).

CONCLUSION

The presence of IgA-aB2GP1 in people with no history of APS-events is the main independent risk factor for the development of these types of events, mainly arterial thrombosis.

Specificities of Platelet Autoantibodies and Platelet Activation in Lupus Anticoagulant Patients: A Relation to their History of Thromboembolic Disease

Lupus anticoagulants (LA) prolong in vitro phospholipid-dependent coagulation tests, but are associated with thromboembolic disease (TE). However, a subgroup of individuals with LA has no TE, and it is therefore desirable to distinguish those at risk for TE from those without. Whether platelets have a primary role in the development of TE is not clear yet. We determined platelet autoantibodies to identify a specific platelet target which is associated with platelet activation in 97 patients with a long history of detectable LA, 65 patients with TE (LA/TE+), and 32 individuals without TE (LA/TE+). Thrombocytopenia was more common in the LA/TE- than in the LA/TE+ group ( P &lt; 0.05). Both groups had platelet antibodies, but the frequency of antibodies was lower in LA/TE+ than LA/TE- patients ( P &lt; 0.01), who had higher antibody titres against glycoprotein IIb/IIIa and glycoprotein Ib/IX ( P &lt; 0.05). Also, their platelets were more activated, as determined by PAC-1 binding ( P &lt; 0.01). These differences were also noted if patients with arterial thrombosis were evaluated separately. These findings in LA/TE- individuals were similar to those in patients with chronic autoimmune thrombocytopenia. However, there was no autoantibody target identifiable to distinguish between LA/TE- from LA-TE+ individuals. We therefore conclude that the presence of platelet antibodies, even if associated with platelet activation, is not sufficient to dispose LA patients to thromboembolic disease.

[Immunity and cancer associated thrombosis]

In cancer patients, thrombosis is commonly found complication. There are many established risk factors which may be responsible for thrombosis in this group of patients. Especially the factors connected with treatment and the cancer itself, seem to be significant in the pathogenesis of thromboembolism. On the other hand, the reactions between cancer, hemostasis and immunological system seem to be important in initiation of the thrombotic process. In this review, on the basis of current literature, we have analyzed the relationship between neoplasmatic thrombosis and immunological disorders. The lack of balance between immunological system and haemostasis in neoplasms is the key issue to solve, in order to correct the long term cancer survival.

Inflammatory bowel disease: Epidemiology, pathology and risk factors for hypercoagulability

Hypercoagulability observed in patients with inflammatory bowel diseases (IBD) may lead to thromboembolic events (TE), which affect the venous and arterial systems alike and are an important factor in patients’ morbidity and mortality. The risk of TE in IBD patients has been demonstrated to be approximately three-fold higher as compared to the general population. The pathogenesis of thrombosis in IBD patients is multifactorial and not fully explained. The most commonly listed factors include genetic and immune abnormalities, disequilibrium between procoagulant and anticoagulant factors, although recently, the role of endothelial damage as an IBD-triggering factor is underlined. Several studies report that the levels of some coagulation enzymes, including fibrinogen, factors V, VII, VIII, active factor XI, tissue factor, prothrombin fragment 1 + 2 and the thrombin-antithrombin complex, are altered in IBD patients. It has been demonstrated that there is a significant decrease of tissue plasminogen activator level, a marked increase of plasminogen activator inhibitor type 1 and thrombin-activable fibrinolysis inhibitor, a significantly lower level of antithrombin III and tissue factor pathway inhibitor. IBD patients have been also observed to produce an increased amount of various anticoagulant antibodies. Hyperhomocysteinemia, which is a potential risk factor for TE was also observed in some IBD patients. Further studies are necessary to assess the role of coagulation abnormalities in IBD etiology and to determine indications for thromboprophylactic treatment in patients at high risk of developing TE.

Thrombotic risk in patients with immune thrombocytopenia and its association with antiphospholipid antibodies

Patients with immune thrombocytopenia (ITP) paradoxically have an increased risk of thrombosis. The presence of antiphospholipid antibodies (aPL) has been observed in a substantial proportion of ITP patients, but its clinical significance remains to be established. This study retrospectively investigated the prevalence and clinical significance of aPL in ITP patients and assessed the risk factors for thrombosis. One hundred and sixty-five subjects with ITP were included in the study and followed for a mean period of 63·4 months. Sixty-nine (41·6%) patients were positive for aPL at diagnosis, and their clinical characteristics and course of ITP were not different from those of aPL-negative patients. Twenty-one (12·7%) patients developed a thrombotic event during follow-up and the cumulative incidence rate ratio of aPL-positive to aPL-negative patients for thromboembolism was 3·15 [95% confidence interval (CI) 1·21-8·17] after adjusting for confounding factors. Lupus anticoagulant and hypertension were identified by Cox regression analysis as independent risk factors for thrombosis [hazard ratio (HR) 4·1, 95% CI 1·4-11·9, P = 0·009 and HR 5·6, 95% CI 1·9-15·8, P = 0·001, respectively]. Our results showed that a substantial proportion of ITP patients were aPL-positive, and that lupus anticoagulant and hypertension were independent risk factors for thrombosis. Detection of aPL can provide useful information for identifying patients at high-risk for developing thrombosis.

[The molecular markers of systemic inflammation response and hemocoagulation in case of endoprosthesis replacement of articulation of hip]

The groups with "compensated" and "decompensated" conditions of organism are marked out according the level of sICAM-1 and neopterin. The surgery of endoprosthesis replacement results in the development of systemic inflammation response syndrome (manifestation of hemostatic and adhesional dysfunctions of endothelium depends on pre-surgery condition of vessel wall). To forecast the risk of development of post-surgery thromboembolic and inflammatory complications it is appropriate to study the content of sICAM-1 and neopterin in pre-surgery period.

IgA anti-beta2-glycoprotein I autoantibodies are associated with an increased risk of thromboembolic events in patients with systemic lupus erythematosus

BACKGROUND

The clinical utility of testing for antiphospholipid antibodies (aPL) of IgA isotype remains controversial.

METHODOLOGY/PRINCIPAL FINDINGS

To address this issue, we reasoned that if IgA aPL contribute to the clinical manifestations of the antiphospholipid syndrome, then an association with thromboembolic events should manifest in patients whose only aPL is of IgA isotype. We performed a retrospective chart review of 56 patients (31 with systemic lupus erythematosus [SLE] and 25 without SLE) whose only positive aPL was IgA anti-beta2-glycoprotein I (isolated IgA anti-beta2GPI) and compared their clinical features with 56 individually matched control patients without any aPL. Patients with isolated IgA anti-beta2GPI had a significantly increased number of thromboembolic events, as compared to controls. When patients were stratified into those with and without SLE, the association between isolated IgA anti-beta2GPI and thromboembolic events persisted for patients with SLE, but was lost for those without SLE. Titers of IgA anti-beta2GPI were significantly higher in SLE patients who suffered a thromboembolic event. Among patients with isolated IgA anti-beta2GPI, there was an increased prevalence of diseases or morbidities involving organs of mucosal immunity (i.e., gastrointestinal system, pulmonary system, and skin).

CONCLUSIONS/SIGNIFICANCE

The presence of isolated IgA anti-beta2GPI is associated with an increased risk of thromboembolic events, especially among patients with SLE. IgA anti-beta2GPI is associated with an increased prevalence of morbidities involving organs of mucosal immunity.

The role of antiphospholipid antibodies toward the protein C/protein S system in venous thromboembolic disease

The association between venous thromboembolism (VTE) and antibodies anti-Protein C (PC)/Protein S (PS) is still uncertain. We performed a case-control study to determine the risk of VTE related to the presence of these auto-antibodies considered independently of the presence of lupus anticoagulant (LAC) or anti-cardiolipin antibodies (ACA). One hundred thirty-five patients with idiopathic VTE and 164 healthy subjects were enrolled. Anti-PC and anti-PS antibodies (both IgG and IgM) were assessed using commercially available ELISA kits. Among cases there was a higher prevalence of elevated anti-PC IgM antibodies than in controls (OR 2.44, 95%CI 1.00-5.94). The presence of anti-PC IgG and anti-PS IgG and IgM antibodies was also higher in cases than in controls, but the difference was not statistically significant. Only five patients had both anti-PC or anti-PS antibodies and LAC or ACA. We performed a stepwise multivariate logistic regression analysis showing that anti-PC IgM>958 percentile was a significant predictor of VTE after adjustment for LAC or ACA (OR 2.52, 95%CI 1.01-6.24)). Larger prospective studies are needed to confirm this finding.

The obstetric antiphospholipid syndrome

The association of persistent presence of circulating antiphospholipid antibodies and thromboembolic events, (recurrent) pregnancy loss or both is termed antiphospholipid syndrome. Pregnancies in women with the syndrome should be regarded as at high-risk for complications. Optimal management consisting of close follow-up and pharmacological treatment can result in about 70-80% live births. Apart from the laboratory diagnosis of the syndrome and pathophysiology, this review will focus on treatment during pregnancy.

Association between cytomegalovirus infection and venous thromboembolism

It has been suggested that cytomegalovirus (CMV) infection may be associated with thrombosis in immunocompromised patients. In addition, an association between CMV infection and thrombotic events in immunocompetent hosts has been sporadically reported. We report on 1 immunocompromised and 8 immunocompetent adults who were admitted to a tertiary medical center and experienced a venous thromboembolic event during CMV infection. None reported previous thromboembolic events. All patients were diagnosed as suffering from acute CMV infection. Seven of the patients had vein thromboses. Significant additional thrombophilia was identified in 5 patients; 1 had 15.3 U/mL anti-cardiolipin IgM antibodies (elevated >7), 2 others were not evaluated for genetic procoagulant tendency. The exact nature of the procoagulant effect of CMV has not yet been clarified. Even though these mechanistic studies are incomplete, we suggest that from the clinical perspective, the presence of CMV infection should be considered a possible risk factor for thrombophilia, justifying a high index of suspicion for possible thrombotic events and subsequent decisions regarding prophylactic anticoagulation.

Reducing thrombotic complications in the perioperative setting: an update on heparin-induced thrombocytopenia

Heparins are widely used in the perioperative setting. Immune heparin-induced thrombocytopenia (HIT) is a serious, antibody-mediated complication of heparin therapy that occurs in approximately 0.5%-5% of patients treated with heparin for at least 5 days. An extremely prothrombotic disorder, HIT confers significant risks of thrombosis and devastating consequences on affected patients: approximately 38%-76% develop thrombosis, approximately 10% with thrombosis require limb amputation, and approximately 20%-30% die within a month. HIT antibodies are transient and typically disappear within 3 mo. In patients with lingering antibodies, however, re-exposure to heparin can be catastrophic. In the perioperative setting, heightened awareness is important for the prompt recognition, diagnosis, and treatment of HIT. HIT should be considered if the platelet count decreases 50% and/or thrombosis occurs 5-14 days after starting heparin, with other diagnoses excluded. On strong clinical suspicion of HIT, heparin should be discontinued and a parenteral alternative anticoagulant initiated, even before laboratory confirmation of HIT is obtained. Subsequent laboratory test results may help with the decision to continue with nonheparin therapy or switch back to heparin. Heparin avoidance in patients with current or previous HIT is feasible in most clinical situations, except perhaps in cardiovascular surgery. If the surgery cannot be delayed until HIT antibodies have disappeared, intraoperative alternative anticoagulation is recommended.

Anti-prothrombin antibodies predict thrombosis in patients with systemic lupus erythematosus: a 15-year longitudinal study

OBJECTIVE

To evaluate the role of anti-prothrombin (anti-PT) antibodies in predicting thrombosis in patients with systemic lupus erythematosus (SLE).

METHODS

An inception cohort of 101 SLE patients (12 males, 89 females; mean age 30 +/- 8 years), was considered. Clinical and laboratory evaluations were regularly performed during a 15-year follow-up (median 108 months) with a special focus on thromboembolic events. Serum samples were collected at time of diagnosis and at least once a year thereafter. IgG and IgM anti-PT, anti-cardiolipin (aCL) and anti-beta(2)glycoprotein I (beta(2)GPI) antibodies were measured by enzyme-linked immunosorbent assay (ELISA); lupus anticoagulant (LAC) was assayed by the dilute Russell's viper venom time and activated partial thromboplastin time tests. The analytical specificity of anti-PT ELISA was investigated. The timing of thrombosis occurrence was calculated using the Kaplan-Meier method.

RESULTS

In the 15-year follow-up, thrombosis occurred in 14 out of the 101 patients: venous thrombosis in nine cases and arterial thrombosis in five. IgG and/or IgM anti-PT, anti-beta(2)GPI and aCL antibodies, and LAC activity were detected in ten, nine, seven, and nine cases, with sensitivity for thrombosis of 71.4%, 64.3%, 50% and 64.3%, respectively. Thrombosis-free survival was 90% at 5 years and 85.8% at 10 and 15 years, respectively. Thrombosis was predicted by anti-PT (P = 0.001), anti-beta(2)GPI antibodies (P = 0.002) and LAC activity (P = 0.001). Moreover, the risk of thrombosis progressively increased with the number of positive antiphospholipid antibody tests. The presence of four positive antibody tests was associated with a risk of thrombosis thirtyfold higher than in their absence.

CONCLUSIONS

This longitudinal study shows that IgG anti-PT antibodies are predictors of thrombosis in SLE patients.

The risk for thromboembolic disease in lupus anticoagulant patients due to pathways involving P-selectin and CD154

Individuals with lupus anticoagulants (LA) are at risk for thromboembolism (TE). Chronic inflammation is an important characteristic in LA patients which may dispose for TE. Platelets play a key role in inflammation and TE. We therefore investigated gene polymorphisms as well as plasma levels of platelet receptors as predictors of TE in 107 LA patients. We compared 74 patients with a history of thromboembolic disease (TE+), 56 with venous thrombosis (VT), 12 with arterial thrombosis (AT), and six patients who had both, with 33 LA patients without previous thrombosis (TE-). The P-selectin Pro715 allele was slightly more frequent in VT (OR = 3.167,95% CI 0.955-10.503; p = 0.0594), but no patient with AT had this allele (OR = 0.099, 95 % CI 0.001-0.790; p = 0.0238) which therefore may protect from AT. Plasma levels of P-selectin, collected a median of 35 months (range 2-329 months) after the last thrombotic event, were higher in patients withVT (p = 0.0096) than in TE-, but not with AT (p = 0.4713). These high P-selectin levels were not explained by the P-selectin polymorphism. The CA repeat polymorphism in the 3'-noncoding region of CD154 was significantly associated with the development of AT (OR = 4.035,95 % CI 1.329-12.249; p = 0.0138). Plasma levels of CD154 were not significantly different among the subgroups. Thus, the Thr715Pro polymorphism of P-selectin and CA repeats of CD154 are differentiating between the risk for VT and AT. Further, soluble P-selectin is elevated in LA patients with previous VT, but its role to predict VT needs to be evaluated in prospective studies.

The clinical significance of anti-prothrombin antibodies for risk assessment of thromboembolism in patients with lupus anticoagulant

INTRODUCTION

Thromboembolism is a common manifestation of lupus anticoagulant (LA), however only a subgroup of LA-patients is affected by thrombosis. Study objective was to investigate whether anti-prothrombin antibodies can identify LA-patients at increased risk for thrombosis.

MATERIALS AND METHODS

In total 79 patients, 50 with (42 men/8 women) and 29 without thrombosis (21 men/8 women), were investigated for their presence of anti-prothrombin IgG and IgM antibodies using assays from two different manufacturers (Aeskulisa=assay I, CoaChrom=assay II).

RESULTS

The prevalence of elevated levels of anti-prothrombin IgG, IgM as well as IgG and/or IgM antibodies was 66% [assayI] (36% [assayII]), 38% (24%) and 72% (50%) in patients with thrombosis and 55% (24%), 28% (28%) and 66% (41%) in patients without thrombosis, respectively. Neither anti-prothrombin IgG or IgM nor IgG and/or IgM antibodies were found to indicate an increased risk for thrombosis. In the subgroup of patients with arterial or venous thrombosis there was also no association between anti-prothrombin antibodies and thrombosis. The comparison of median levels of IgG and IgM anti-prothrombin antibodies between patients with and without thrombosis yielded a borderline statistically significant difference only for anti-prothrombin IgG antibodies by using assay II (p=0.033), all other comparisons were not statistically significant.

CONCLUSIONS

In conclusion, presence of anti-prothrombin antibodies was not associated with thromboembolism in LA-patients.

[Multiple sclerosis and antiphospholipid syndrome--difficulties in differential diagnostics]

Antiphospholipid syndrome (Hughes syndrome) is an autoimmune disorder with production of antibodies against phospholipids and phospholipid binding peptides in human organism, that is associated with thrombotic events. Venous and/or arterial tromboembolism and recurrent pregnancy loss at women are the most frequently observed clinical manifestations. Neurological symptoms are common and they can often mime multiple sclerosis. That is why antiphospholipid antibodies must be concerned in differential diagnostics of multiple sclerosis, particularly with the atypical course and clinical pattern.

[Antiphospholipid antibodies--risk factors for venous thromboembolism and arterial thrombosis]

The antiphospholipid syndrome (APS) is a disorder of increased risk of thrombotic complications: venous thromboembolic disease, arterial thrombosis, and recurrent pregnancy loss. There is a much higher rate of recurrences of these thrombotic events as well. Some recent clinical trials have shown the superiority of the lupus anticoagulant and anti-beta2 glycoprotein-I antibodies assays over anticardiolipin determination for the identification of APS patients at risk for thromboembolic complications. The principles of the primary prophylaxis, treatment and secondary prophylaxis of thrombotic complications in patients with antiphospholipid syndrome has been also summarized.

[Antiphospholipid syndrome]

Antiphospholipid syndrome (APS) is characterized by recurrent arterial or venous thromboembolism or pregnancy loss in association with antibodies directed against anionic phospholipids or plasma proteins bound to anionic phospholipids. A common cause of the huge variety of clinical manifestations is vaso-occlusive disease and not vasculitis in venous or arterial blood vessels of different sizes and sites (i.e. deep vein thrombosis, pulmonary embolism, cerebrovascular disease). In accordance with this, fetal abortion, typically beyond the tenth week of gestation, is also caused by infarctions of blood vessels in the placenta. Establishing the correct diagnosis of APS is not easy. To estimate the risk of thrombotic complications is challenging, as well as the questions of, which, how long and in what strength anticoagulation is recommended. This paper should enable the reader to apply international consensus classification criteria correctly, to interpret the different laboratory tests for anti-phospholipid antibodies and to gain an awareness of the different forms of anticoagulation in order to stratify therapeutic decisions.

A prospective study of the prevalence of heparin-induced antibodies and other associated thromboembolic risk factors in pediatric patients undergoing hemodialysis

Heparin, which is used at high doses in hemodialysis patients, may induce antibodies favoring thromboembolic complications. We prospectively investigated the prevalence of heparin-induced platelet-reactive antibodies in a cohort of 38 pediatric hemodialysis patients, by means of heparin/platelet factor 4 (H/PF4) ELISA and heparin-induced platelet activation assay (HIPA). We also assessed other acquired and congenital hypercoagulable states. Heparin-induced antibodies were detected in 13 and 21% of patients with HIPA and ELISA, respectively. Anti-H/PF4 antibodies were negatively correlated with the number of hemodialysis sessions. These antibodies disappeared after a median time of 6 months despite continuing heparin treatment. The prevalence of antiphospholipid antibodies was 21% (anticardiolipin 10.5%, anti-beta2GPI 13%, and lupus anticoagulant 5%). Blood levels of homocysteine, factor VIII, and fibrinogen were significantly higher and factor II levels were significantly lower in hemodialysis patients than in controls, whereas factor VII, factor IX, and natural coagulation inhibitor levels were similar in patients and controls. Overall, 26 of 38 patients had at least one biomarker of hypercoagulability, but only 1 patient, without anti-H/PF4 antibodies, presented with thrombosis. In conclusion, heparin induces the transient production of anti-H/PF4 antibodies in children undergoing hemodialysis, but other abnormalities probably contribute to hypercoagulability. These findings may help to improve the diagnosis and management of thrombotic events in hemodialysis patients.

Recurrent thrombosis in patients with deep vein thrombosis and/or venous thromboembolism associated with anticardiolipin antibodies

Anticardiolipin antibodies represent one of the main hypercoagulation states associated with venous thromboembolism. The aim of this work was to evaluate symptomatic recurrent thrombosis in patients with anticardiolipin antibodies and deep vein thrombosis of the lower limbs with or without thromboembolism. Sixty patients who suffered from deep vein thrombosis were observed for a 5-year period, whether they had anticardiolipin antibodies or not. The group was made up of 34 females and 26 males with ages ranging from 13 to 73 years. All were diagnosed with deep vein thrombosis by means of phlebography and were tested for anticardiolipin antibodies by use of the ELISA method. The symptomatic signs of recurrent thrombosis were evaluated during this period. In total, 56.6% of the group were considered above normal for anticardiolipin antibodies, 25% positive, another 31.6% borderline, and 43.4% negative. Patients were tested positive when the anticardiolipin antibody count was >15 units/mL, borderline between 10 and 15 units/mL, and normal when <10 units/mL. The method of relative risk was used for statistical analysis of the results. Four positive patients, 1 borderline, and 1 normal patient had recurrent events of thrombosis. In the statistical analysis the relative risk for recurrent thrombosis in the positive patients was 6.0; CI 95%; 1.2 to 29.5. In conclusion patients with deep vein thrombosis who are positive for anticardiolipin antibodies present a higher risk of recurrent thrombosis.

Gene-expression patterns predict phenotypes of immune-mediated thrombosis

Antiphospholipid antibody syndrome (APS) is a complex autoimmune thrombotic disorder with defined clinical phenotypes. Although not all patients with elevated antiphospholipid antibody (aPLA) levels develop complications, the severity of these potential events mandates aggressive and extended lifelong anti-thrombotic therapy. One hundred twenty-nine patients (57 patients with APS and venous thromboembolism [VTE], 32 patients with VTE without aPLA, 32 patients with aPLA only, and 8 healthy patients) were enrolled. RNA from peripheral-blood collection was used for DNA microarray analysis. Patterns of gene expression that characterize APS as well as thrombosis in the presence of aPLA were identified by hierarchical clustering and binary regression methods. Gene-expression profiles identify and predict individuals with APS from patients with VTE without aPLA. Importantly, similar methods identified expression profiles that accurately predicted those patients with aPLA at high risk for thrombotic events. All profiles were validated in independent cohorts of patients. The ability to predict APS, but more importantly, those patients at risk for venous thrombosis, represents a paradigm for a genomic approach that can be applied to other populations of patients with venous thrombosis, providing for more effective clinical management of disease, while also reflecting the possible underlying biologic processes.

Clinicopathological features of lupus anticoagulant; experience at AFIP during last seven years

BACKGROUND

The lupus anticoagulant (LA) belongs to family of immunoglobulins, most commonly an IgG isotype. These antibodies have been identified most frequently in association with thromboembolic events, recurrent fetal loss and thrombocytopenia. The aim of the present study was to evaluate the presenting clinical and pathological features in patients LA positive presenting at AFIP Rawalpindi over the period of Jan 1993 to Nov 2000.

MATERIAL/METHODS

Retrospective analysis of patients presenting with positive LA was carried out.

RESULTS

1583 suspected cases were screened for LA including 1370 females and 213 males. 1024 cases presented with history of recurrent abortions, 292 with thrombosis, 152 with thrombotic strokes before the age of 45 years, 52 with thrombocytopenia and 63 with miscellaneous disorders. Out of 1024 patients tested for recurrent abortions, 130 (13%) females were positive for lupus anticoagulant. Ten (6.5%) of 152 patients presenting with strokes were found positive. Out of 292 cases presenting with thrombosis 17 (5.9%) were found positive.

CONCLUSIONS

The lupus anticoagulant prevalence in Pakistani patients with recurrent fetal loss, stroke and thrombosis is statistically significant. Clinicians should be made aware of association of LA with various diseases. The successful management of these patients depends upon close liaison with obstetricians, physicians and haematologists.

Autoantibody to CD40 ligand in systemic lupus erythematosus: association with thrombocytopenia but not thromboembolism

OBJECTIVES

To examine the prevalence, clinical associations and pathogenic roles of autoantibodies to CD40 ligand (CD40L) in patients with systemic lupus erythematosus (SLE).

METHODS

Plasma anti-CD40L antibodies from 125 patients with SLE, 24 with primary antiphospholipid syndrome (APS) and 90 with idiopathic thrombocytopenic purpura (ITP) and from 62 healthy individuals were measured with an enzyme-linked immunosorbent assay (ELISA). HeLa cells transfected with human CD40L cDNA (HeLa/CD40L) were used to confirm the presence of anti-CD40L autoantibodies. The effect of anti-CD40L antibodies on the CD40L-CD40 interaction was evaluated by observing CD40L-induced IkappaB activation in CD40-expressing fibroblasts.

RESULTS

Anti-CD40L autoantibody was detected in seven (6%) SLE, three (13%) primary APS and 11 (12%) ITP patients, but in no healthy controls. Antibody binding in an ELISA was competitively inhibited by membrane components of HeLa/CD40L. Anti-CD40L antibody-positive IgG specifically bound the surface of living HeLa/CD40L, as shown by flow cytometry. The frequency of thrombocytopenia was significantly higher in SLE patients with the anti-CD40L antibody than in those without (100 vs 14%; P<0.00001), whereas there was no association between the anti-CD40L antibody and thrombosis. Binding of the anti-CD40L antibodies in patients' plasma to CD40L was competitively inhibited by a series of mouse anti-CD40L monoclonal antibodies. Anti-CD40L antibody-positive IgG failed to inhibit CD40L-induced IkappaB activation.

CONCLUSIONS

Anti-CD40L autoantibody is associated with thrombocytopenia but not thromboembolism. Our findings are potentially useful in understanding the complex roles of CD40L in the pathophysiology of thrombosis and haemostasis as well as the thromboembolic complications that occur during treatment with anti-CD40L humanized antibody.

IgG and IgM isotypes of anti-cardiolipin and anti-beta2-glycoprotein i antibodies reflect different forms of recent thrombo-embolic events

We correlated the distribution and levels of serum anti-cardiolipin (aCL) and anti-beta(2)-glycoprotein-1 antibodies (anti-beta(2)-GPI) of the IgG and IgM isotypes to the clinical spectrum of recent (<6 months) thrombo-embolic events in a cohort of 162 patients. Clinical information was obtained by questionnaires from the referring physicians. Cerebro-vascular infarction (CVI) had taken place in 82 patients, deep venous thrombosis (DVT) in 34, pulmonary embolism (PE) in 14, myocardial infarction (MI) in four, and other thromboses in 28 patients. SLE was the most commonly associated rheumatic disease and accounted for 20 (12%) patients. In 124 (77%) patients no underlying rheumatic disease was identified. Isolated IgG aCL was found in 31 of 48 patients with DVT/PE (65%), but in only 21 of 82 patients with CVI (26%); p<0.0001. IgG anti-beta(2)-GPI were detected in 23 (48%) DVT/PE patients, but in only 13 (16%) CVI patients; p<0.001. The IgG class anti-beta(2)-GPI positive patients had significantly higher levels of IgG aCL (mean 65 units) compared to IgG anti-beta(2)-GPI negative patients (mean 29 units); p<0.0001. In contrast, isolated IgM aCL was found in nine (19%) patients with DVT/PE, but in 46 (56%) CVI patients; p<0.0001. Only ten patients had IgM anti-beta(2)-GPI. The present study shows that the IgG and IgM aCL isotypes seem to define different clinical subsets of patients with thrombo-embolic events with IgG aCL being most prevalent in the group having DVT/PE, IgM aCL being found primarily among CVI patients.

Acquired Activated Protein C Resistance Associated with IgG Antibodies against β2-Glycoprotein I and Prothrombin as a Strong Risk Factor for Venous Thromboembolism

Background: Venous thromboembolic events such as deep vein thrombosis and pulmonary embolism are common manifestations of antiphospholipid syndrome. Our aim was to clarify the roles of anti-phospholipid (aPL) antibodies in the pathogenesis of venous thromboembolism (VTE) in patients with systemic lupus erythematosus (SLE).

Methods and Results: We examined anti-cardiolipin/β2-glycoprotein I (anti-CL/β2-GPI) antibody concentrations, anti-phosphatidylserine/prothrombin (anti-PS/PT) antibody concentrations, and lupus anticoagulant (LA) activity in 87 patients with SLE (21 with VTE and 66 without thrombosis). Both anti-CL/β2-GPI and anti-PS/PT antibodies strongly correlated with LA activity. Multivariate logistic analysis confirmed that both anti-CL/β2-GPI and anti-PS/PT antibodies were significant independent risk factors for VTE (odds ratios = 4.98 and 7.54, respectively; 95% confidence intervals, 1.51–16.4 and 2.30–24.7, respectively). We therefore studied the in vitro effects of IgG fractions containing anti-CL/β2-GPI or anti-PS/PT antibodies on the anticoagulant activity of activated protein C (APC) and found that purified IgG containing anti-CL/β2-GPI or anti-PS/PT antibodies significantly hampered the anticoagulant activity of APC. We also studied the ability of IgG fractions to impede the anticoagulant activity of APC before and after complete removal of anti-CL/β2-GPI or anti-PS/PT antibodies by adsorption. Removal of anti-CL/β2-GPI or anti-PS/PT antibodies from all positive IgG samples clearly decreased the inhibitory effect of those samples on APC anticoagulant activity.

Conclusions: Anti-CL/β2-GPI and anti-PS/PT antibodies independently cause APC resistance, which may contribute to risk of VTE in patients with SLE.

Acquired hemophilia masked by warfarin therapy: report on two cases

Spontaneous appearance of acquired anticoagulants is a rare phenomenon. We present two cases, where such antibodies against factor VIII were masked by warfarin therapy. The two patients were anticoagulated with warfarin due to mechanical heart valve and recurrent thromboembolic events, respectively. Different therapies against the inhibitor of factor VIII were used in the two cases. One patient received corticosteroids and high-dose gammaglobulin with temporary effect and was then effectively treated with cyclophosphamide. The other patient was successfully treated with cyclosporine. The special problems of keeping the balance between thrombosis and bleeding in this group of patients with need of anticoagulation due to mechanical heart valves or other thrombogenic factors are discussed.

[Paraneoplastic syndrome associated with antiphospholipid antibodies]

In patients with malignant tumour signs and symptoms develop that cannot be explained on the basis of the mass effect produced by either primary tumour or its metastases, production of a hormone associated with tissue type giving rise to the malignant tumour, or patients' immune status. These symptom complexes are known as paraneoplastic syndrome. It is known that the patients with malignant tumours are prone to develop venous thromboembolism in any stage of their disease. It is suggested that thromboembolic manifestations in cancer patients may be part of the secondary antiphospholipid syndrome (APS) and an example of the paraneoplastic autoimmunity, eg., paraneoplastic syndrome. Antiphospholipid antibodies (APA), e.g., anticardiolipin antibodies (ACA) and circulating lupus anticoagulant (LAC) are known to predispose to venous and arterial thromboses. The growing number of clinical reports on the association of APA and malignant tumours suggests that APA may be one of contributory factors in the paraneoplastic thromboembolism occurring in malignancy.

Reactivity profiles of autoantibodies to different phospholipids and the phospholipid-binding protein beta2-glycoprotein I in patients with clinical symptoms related to thromboembolic and/or vasculopathic events with or without connective tissue diseases

To study the antigenic and epitope specificities of anti-phospholipid Ab in detail, we investigated 177 patients without (62 with APS-related systemic clinical symptoms, 115 with microangiopathies) and 164 patients with connective tissue diseases (CTD). Ab associated with primary APS (pAPS) seem to show a restricted specificity (phospholipid/beta2-GPI-complexes), whereas those in secondary APS (sAPS) react additionaly with pure beta2-GPI. Simultaneously, beta2-GPI-independent Ab were also frequently present in both conditions (50% of all Ab-positive sera). In CTD patients, the reactivity profile "pure beta2-GPI + phospholipid/beta2-GPI-complexes" is significantly associated with clinically manifest sAPS. Comparing cardiolipin and phosphatidylserine as antigenic target, the overall concordance (crossreactivity?) between both assays was lower than expected (52%), being highest in pAPS (87%) and sAPS (65%). Based on these results, a two-step procedure for reliable serological diagnosis of APS could be recommended: Ab-screening using a mix of phospholipids complexed with beta2-GPI (sensitivity > 90% for Ab concentrations above 20 U/ml) followed by an assay allowing the simultaneous detection of all relevant antigenic and epitope specificities.

Thromboembolism in paediatric lupus patients

Paediatric patients with systemic lupus erythematosus (SLE) and antiphospholipid antibodies (aPL), specifically lupus anticoagulants (LAC) are at high risk of developing thromboembolic events (TE). Our objectives were to determine the prevalence of TE in paediatric SLE patients with LAC and to determine if anticoagulation was effective to decrease morbidity, and prevent recurrent TE. We reviewed data on 149 paediatric SLE patients treated over 10 years. In all, 24 patients (16%) were LAC positive, and 21 TE occurred in 13 of these LAC positive patients (54% incidence of TE in LAC positive patients). The events were cerebral venous thrombosis (9), arterial stroke (3), deep venous thrombosis (4), pulmonary embolism (2), other venous event (1) and other arterial events (2). The median duration between SLE diagnosis and first TE was 15.2 months (range 0-62), and the median age at first TE was 15.1 years (range 11.4-18.4). Long-term anticoagulation was prescribed, and eight patients (62%) were transferred to adult care on lifelong oral warfarin; four (31%) remain under our care on lifelong warfarin, and one patient died of causes unrelated to her TE. No patient has been identified with deficiencies of protein C, protein S or antithrombin III. One patient is heterozygous for Factor V Leiden, and one is heterozygous for both the Prothrombin 20210A mutation and the MTHFR (methylene tetrahydrofolate reductase) mutation. Four patients had recurrent TE (31%), and three were not anticoagulated at the time of their second event. One patient had two recurrences on therapeutic anticoagulation. Thromboembolic events are prevalent in the LAC positive paediatric SLE population, and consideration for lifelong anticoagulation must occur after an initial TE.

Is the determination of anti-beta2 glycoprotein I antibodies useful in patients with venous thromboembolism without the antiphospholipid syndrome?

Anti-beta2-glycoprotein I (beta2GPI) antibodies are frequently found in patients with lupus anticoagulant (LA). To investigate the prevalence of antibeta2GPI antibodies and their clinical impact in patients with a history of venous thromboembolism (VTE) without LA/anticardiolipin antibodies (ACA), we studied 503 patients [128 (36.2%) men, median age 41 years (interquartile range, IQR 28-54 years)] with previous thrombosis. A group of 113 individuals without VTE [43 (38.1%) men, age 46.7 years (IQR 38-52 years)] served as a control group. Among 418 patients without LA/ACA, anti-beta2GPI-IgG levels were elevated in seven (1.7%), -IgM in 15 (3.6%) and -IgA in 14 (3.3%) cases; in 58 patients with ACA, anti-beta2GPI-IgG levels were elevated in two (3.4%), six (10.3%) and three (5.2%), and in 27 with LA, they were elevated in 18 (66.7%), 19 (70.4%) and 10 (37%) respectively. Thus, the prevalence of elevated anti-beta2GPI antibodies was not increased in patients without LA/ACA but was strongly associated with LA. Patients without ACA/LA who had a recurrent event did not have higher prevalence of elevated anti-beta2GPI-IgG, -IgM or -IgA antibodies than those without a recurrent event. Thus, elevated antibeta2GPI antibodies are not likely to be a predictor of recurrent events in patients without LA. We conclude that determination of anti-beta2GPI antibodies does not improve the clinical management of patients with a history of VTE without LA/ACA.

Different immunophenotypes in Buerger's disease

Recently, we reviewed the morphology of 31 specimens of thromboangiitis obliterans (TAO, Buerger's disease) in a multivariate analysis and showed that certain novel features of the affected vessels are different from arteriosclerosis obliterans (ASO) and thromboembolism. However, the pathogenic concept of TAO is still controversial. We applied immunohistochemistry to 58 amputated lower extremities and five autopsy controls. At specific sites of the diseased vessels, different cellular components were immunotyped by CD3, CD4, CD20, CD31, CD68, actin and desmin. These results were carefully compared among different diagnostic groups of vasoocclusive lesions by statistical methods. Some unique characteristics of TAO were identified when compared with ASO or thromboembolism. Consistent with a primary inflammatory and immunogenic lesion, lymphocytes and especially CD4+ T cells emerged significantly in TAO vessels and their adventitia. In the subset of definite TAO cases defined by all clinical criteria, the linear arrangement of macrophages, and B- and T-lymphocytes along vascular elastic fibers was the most striking additional finding, suggesting elastic fibers are an important immunogen. However, this feature was not apparent in closely related cases, otherwise similar to TAO and different from ASO and thromboembolism. Thus, our results indicate a heterogeneous group of TAO diseases, suggesting that damage to elastic fibers may be a secondary change to primary inflammation.

Association between inherited thrombophilias, antiphospholipid antibodies, and lipoprotein A levels and venous thromboembolism in pregnancy

The objective of this study is to evaluate the association between venous thromboembolism (VTE) in pregnancy with thrombophilic factors. Thirty pregnant women with VTE were compared with 30 pregnant women matched by age and race without VTE and evaluated for risk factors and thrombophilia. Statistical analysis used two-tailed Fisher's exact test. VTE distribution was 30% in first trimester, 9% in 2nd trimester, 26% in 3rd trimester and 35% postpartum. Seventeen (57%) of VTE cases versus 2 (7%) of control cases had specific thrombophilia diagnosis ( p <0.001). The results were: Factor V Leiden mutation (27 vs. 3%) p = 0.026, MTHFR homozygous 677 mutation (10 vs. 44%) p = 0.017, prothrombin gene mutation (11 vs. 0%), protein C deficiency (7 vs. 0%), antiphospholipid antibodies (27 vs. 3%) p = 0.026, mean lipoprotein levels 49 versus 23 mg/dL, p = 0.008, mean homocysteine levels 7.8 versus 7.1 umol/L. An association is suggested between thromboembolic events in pregnancy and thrombophilia, especially Factor V Leiden gene mutation and elevated antiphospholipid antibodies. A new finding is the association of elevated lipoprotein A levels with thromboembolic events in pregnancy.

Anticardiolipin antibodies as a risk factor for venous thromboembolism in a population-based prospective study

Anticardiolipin antibodies, one of the family of 'antiphospholipid' antibodies, increase the risk of venous thromboembolism in the presence of autoimmune disease. Our objective was to determine prospectively whether there is a positive association between anticardiolipin antibodies and venous thromboembolism in ostensibly healthy adults. We conducted a nested case-control study (n = 317 patients and n = 655 control subjects) in a longitudinal study of over 20 000 participants. Baseline (prediagnosis) anticardiolipin IgG and IgM antibodies were assessed by enzyme-linked immunoassays. Venous thromboembolism was validated using standardized criteria for venous thrombosis and pulmonary embolism. There was no association between anticardiolipin antibodies and subsequent venous thromboembolism occurrence, overall or in any subgroup. For example, the multivariate-adjusted relative risk was 0.88 (95% confidence interval, 0.43, 1.78) for greater than versus less than the 95th percentile of anticardiolipin IgG. In conclusion, in this general population sample, an elevated anticardiolipin antibody level was not a risk factor for venous thromboembolism.

Antiphospholipid antibodies

OBJECTIVE

To review the role of lupus anticoagulants in the pathogenesis of both venous and arterial thromboembolic events, as well as in recurrent spontaneous abortions. The pathophysiology of lupus anticoagulants and associated antiphospholipid antibodies (eg, anticardiolipin antibodies) is also discussed.

DATA SOURCES

Review of the recent medical literature.

DATA EXTRACTION AND SYNTHESIS

Key articles in the recent medical literature dealing with lupus anticoagulants and their role in pathogenesis of thromboembolic events were reviewed. Plasma proteins that have an affinity for binding to "perturbed cellular membranes" have been identified as the antigenic targets for antiphospholipid antibodies. Thus, the concept of antiphospholipid antibodies needs to be reevaluated. Perhaps a better term is antiprotein-phospholipid antibodies. The principal antigenic protein targets are beta(2)-glycoprotein I, prothrombin, and a wide range of additional proteins that interact with activated cellular membranes, including protein C, protein S, annexin V, etc. Most research reported in the literature has focused on beta(2)-glycoprotein I and human prothrombin.

[Antiphospholipid antibodies as risk factor for venous thromboembolism]

The aim of the following study was to determine the prevalence of lupus anticoagulant (LA) and anticardiolipin antibodies (ACL) in patients with a history of venous thromboembolism (VTE). The patient group comprised 218 subjects with VTE before the age of 45, recurrent VTE or thrombosis in an unusual site. The control group consisted of 218 age, and sex-matched healthy individuals. LA and/or ACL were detected in 19 among 218 patients (8.7%). Lupus anticoagulant was found in 17 patients with VTE and in none out of 218 controls. The odds ratio for having venous thromboembolism was 14.1 (95% CI: 1.8-108.8) for patients with LA. Lupus anticoagulant is significantly associated with VTE. The prevalence of anticardiolipin was similar in patients and in controls. The results of our study indicate that anticardiolipin antibodies are not associated with venous thromboembolism.

Fatal tumor thrombosis due to an inferior vena cava leiomyosarcoma in a patient with antiphospholipid antibody syndrome

We describe a patient with antiphospholipid antibody syndrome (APS) who died because of relentless inferior vena cava (IVC) tumor thrombosis due to an unsuspected leiomyosarcoma. Laboratory confirmation for APS was provided by functional identification of a lupus anticoagulant and anticardiolipin IgG and anti-beta2-glycoprotein I IgM antibodies. Although sensitive for detecting vascular obstruction, radiocontrast venography and magnetic resonance imaging and angiography detected the IVC thrombosis but failed to distinguish its malignant nature. Concomitant refractory thrombocytopenia prevented further invasive diagnostic and therapeutic maneuvers for progressive, severe IVC thrombosis unresponsive to aggressive treatment of APS. Deep venous thrombosis refractory to anticoagulant and immunomodulatory therapies in a patient with APS may be due to a concomitant underlying malignancy, such as a leiomyosarcoma, causing vascular obstruction.

Anticardiolipin antibodies and risk of thromboembolic disease in young Jamaican women

BACKGROUND

Anticardiolipin antibodies (aCL) are a heterogeneous group of antiphospholipid antibodies that are associated with arterial and venous thrombosis. We measured aCL in women, aged 15-49 years, to determine if they are an independent risk factor for thromboembolic disease.

STUDY DESIGN

Case--control study

METHODS

Fifty cases were studied including venous thromboembolism (n=29), stroke and myocardial infarction (n=21), along with 148 age-matched controls. Serum samples were assayed for aCL and anti-beta2 glycoprotein 1 antibodies using the enzyme-linked immunosorbent assay (ELISA). Information on other risk factors was obtained by a standardized questionnaire.

RESULTS

aCL were present in 16/50 (32%) of cases compared with 25/148 (17%) of controls (P[?]=[?]0.02). Unadjusted odds ratio (OR) and 95% confidence interval (95% CI) for thromboembolic disease associated with aCL was 2.32 (1.10--4.87). Other risk factors were hypertension, 2.93 (1.20--7.17) and a history of other heart diseases, 12.78 (1.32--123.60). Adjustment for hypertension, diabetes, oral contraceptive use, smoking, alcohol use, varicose veins, a family history of cardiovascular disease and a history of other heart diseases yielded OR (95%CI) 2.99 (1.32--6.80). beta2 glycoprotein 1-dependent aCL were also an independent risk factor, OR 4.56 (1.76--17.83). Subgroup analysis was carried out separately for cases of MI and stroke and for venous thrombosis. Adjusted OR (95% CI) associated with aCL in cases of MI and stroke was 1.76 (0.46--6.73) and 3.32 (1.15--9.54) for venous thromboembolism.

CONCLUSION

aCL are a risk factor for thromboembolic disease in young Jamaican women. They confer a strong independent risk for venous thromboembolism.

A cross sectional study of antiphospholipid-protein antibodies in patients with venous thromboembolism

OBJECTIVE

To look for an association between venous thromboembolism (VTE) and antiphospholipid antibodies (aPL) in patients without Systemic Lupus Erythematosus (SLE) when implementing, beside conventional assays, new tests for aPL screening directed towards purified proteic targets.

METHODS

We conducted a cross-sectional, hospital-based study of consecutive unselected outpatients. We compared VTE+ patients to VTE- among 398 consecutive unselected outpatients referred for clinical suspicion of VTE. To detect aPL, the following ELISAs were performed: 1) a conventional standardized ELISA 2) an improved APA assay, 3) an anti-Beta2GPI ELISA, 4) an anti-Annexin V ELISA, 5) an anti-Prothrombin ELISA. We sought an association between VTE and aPL through a quantitative (t-test) and a qualitative comparison (chi-square test, according to the cut-off values set as the 95th percentile of aPL distribution). First we conducted an analysis of all patients. Then we stratified them into 2 subgroups, with or without a wellknown risk factor for VTE (prolonged immobilization >72h, surgery or trauma within the past three months, current malignancy).

RESULTS

61% of patients were classified as VTE-positive. Before stratification, we did not find any significant association between the VTE status and aPL. However, after stratification, in the subgroup without risk factors for VTE, the frequency of positive values as regards the anti Prothrombin antibodies detection was significantly higher in VTE+ patients (p = 0,04).

CONCLUSION

The presence of anti Prothrombin antibodies might be an independent risk factor of VTE. However systematic screening for aPL in non SLE patients referred for VTE suspicion at the time of the thrombo-embolic event has little clinical relevance.

Heparin antibodies and thromboembolism in heparin-coated and noncoated ventricular assist devices

OBJECTIVE

Coating of ventricular assist devices (VADs) with heparin improves the biocompatibility and may reduce the need for systemic anticoagulation. However, heparins are associated with the risk of formation of heparin/platelet factor 4 antibodies (HPF4/A) and the development of heparin-associated thromboemboli. We analyzed the occurrence of HPF4/A and thromboembolism in patients with heparin-coated and noncoated VADs.

METHODS

One hundred patients were enrolled in the investigation. Fifty-seven received a heparin-coated (group 1) and 43 a noncoated (group 2) VAD. HPF4/A testing was performed before and 2 and 12 weeks after implantation by the heparin platelet factor 4 enzyme-linked immunosorbent assay.

RESULTS

There was no significant difference in the occurrence of HPF4/A in the 2 groups (P =.102). Before the operation, 21 of the patients in group 1 had positive test responses and 25 in group 2. No patient had HPF4/A after termination of systemic heparinization. In group 1 there was no significant difference in the incidence of recurrent pump thromboses in patients who had positive test responses for HPF4/A (n = 11) when compared with those who had negative test responses (n = 9, P =.89). Twenty-one patients had HPF/A but no thromboembolism. However, all 22 patients who had thromboembolism had HPF4/A.

CONCLUSIONS

Heparin coating of the VAD surface does not enhance the occurrence of HPF4/A-associated immunologic or thrombogenic reactions. However, the presence of these antibodies is strongly associated with an increased risk of thromboembolism in patients with a VAD.