Immunoglobulin G (IgG) anticardiolipin antibodies and recurrent cardiovascular events. A systematic review and Bayesian meta-regression analysis

Low-grade endotoxemia and risk of recurrent thrombosis in primary antiphospholipid syndrome. The multicenter ATHERO-APS study

INTRODUCTION

Low-grade endotoxemia is associated with systemic inflammation, enhanced oxidative stress and cardiovascular events in different clinical settings, but its possible role as "second hit" in patients with primary antiphospholipid syndrome (PAPS) has never been investigated.

PURPOSE

To evaluate the relationship between plasma lipopolysaccharide (LPS) levels, oxidative stress markers and risk of thrombosis in the prospective multicenter ATHERO-APS study.

METHODS

Baseline LPS, soluble NADPH-oxidase 2-derived peptide (sNOX-dp), H2O2 production, hydrogen peroxide breakdown activity (HBA), and nitric oxide (NO) bioavailability were compared in 97 PAPS, 16 non-thrombotic aPL carriers and 21 controls (CTRL) matched for age and sex. Correlations among laboratory variables were explored by Rho Spearman's correlation (rS). Cox-regression analysis was performed to assess the association between LPS and risk for a composite outcome of cardiovascular death, venous and arterial thromboembolism.

RESULTS

In the whole cohort (median age 51 years (IQR 43-60), 72 % female), PAPS demonstrated higher levels of LPS, sNOX-dp and H2O2 and lower levels of NO and HBA compared to non-thrombotic aPL carriers and CTRL. LPS levels were inversely correlated with HBA (rS: -0.295, p = 0.001) and NO (rS: -0.322, p < 0.001) and directly correlated with sNOX-dp (rS:0.469, p < 0.001) and H202 (rS:0.282, p < 0.001). PAPS showed higher levels of LPS, sNOX-dp and H2O2 and lower levels of NO and HBA compared to aPL carriers and CTRL. After a 4.7 years follow-up of, 11 composite outcomes were reported in PAPS (2.5 per 100 patient-years) while none was observed in aPL carriers. On Cox-regression analysis, patients with LPS above the median (>23.1 pg/ml) had a 5-fold increased risk of composite outcome compared to those with LPS below the median, after adjustment for sex, age, diabetes, and global antiphospholipid syndrome score.

CONCLUSION

Low-grade endotoxemia is associated with an increased oxidative stress and a higher risk of thrombosis in PAPS. Its prognostic value in carriers needs to be investigated in larger cohorts.

Factor V Leiden, prothrombin, MTHFR, and PAI-1 gene polymorphisms in patients with arterial disease: A comprehensive systematic-review and meta-analysis

INTRODUCTION

The role of inherited thrombophilia in arterial disease is uncertain. We performed a systematic-review and meta-analysis of inherited thrombophilia in cerebrovascular (CVD), coronary heart (CHD), and peripheral artery disease (PAD) patients.

MATERIALS AND METHODS

MEDLINE and EMBASE were searched up to February 2022. Pooled prevalences (PPs) and odds ratios (ORs) with 95 % confidence intervals (95%CI) were calculated in a random-effects model. Factor V Leiden (G1691A), prothrombin (G20210A), MTHFR C677T/A1298C and PAI-1 4G/5G were evaluated.

RESULTS

377 studies for 98,186 patients (32,791 CVD, 62,266 CHD, 3129 PAD) and 108,569 controls were included. Overall, 37,249 patients had G1691A, 32,254 G20210A, 42,546 MTHFR C677T, 8889 MTHFR A1298C, and 19,861 PAI-1 4G/5G gene polymorphisms. In CVD patients, PPs were 6.5 % for G1691A, 3.9 % for G20210A, 56.4 % for MTHFR C677T, 51.9 % for MTHFR A1298C, and 77.6 % for PAI-1. In CHD, corresponding PPs were 7.2 %, 3.8 %, 52.3 %, 53.9 %, and 76.4 %. In PAD, PPs were 6.9 %, 4.7 %, 55.1 %, 52.1 %, and 75.0 %, respectively. Strongest ORs in CVD were for homozygous G1691A (2.76; 95 %CI, 1.83-4.18) and for homozygous G20210A (3.96; 95 %CI, 2.05-7.64). Strongest ORs in CHD were for homozygous G1691A (OR 1.68; 95%CI, 1.02-2.77) and G20210A (heterozygous 1.49 95%CI, 1.22-1.82; homozygous 1.54 95%CI, 0.79-2.99). The OR for PAI-1 4G/4G in PAD was 5.44 (95%CI, 1.80-16.43). Specific subgroups with higher PPs and ORs were identified according to age and region.

CONCLUSIONS

Patients with arterial disease have an increased prevalence and odds of having some inherited thrombophilia. Some thrombophilia testing may be considered in specific subgroups of patients.

The interaction of persistent antiphospholipid antibodies positivity and cigarette smoking is associated with an increased risk of cardiovascular events: Cross-sectional and longitudinal analysis

BACKGROUND

The antiphospholipid antibody (aPL)-positivity was suggested as a nontraditional risk of coronary artery disease (CAD) and it was associated with cigarette smoking. The co-occurrence of them was usually reported in individuals with cardiovascular diseases. This study was to demonstrate their interaction on the increasing risk of cardiovascular events.

METHODS AND RESULTS

A total of 826 consecutive male individuals who underwent coronary angiography (CAG) /percutaneous coronary intervention (PCI) were prospectively followed and classified into three groups based on different smoking statuses. The current smoking subjects had the highest occurrence of aPL-positivity, including aCL IgM (20.1%) and aβ2GP1 IgM (15.5%). IgM isotype positivity was an independent risk factor of CAD in the multivariate model, OR: 2.70 (1.52-4.80) for aCL IgM and OR:2.50 (1.35-4.63) for aβ2GP1 IgM.The interaction of current smoking and IgM isotype positivity was significantly associated with increased risk of CAD, OR: 8.75(4.59-16.66) for aCL IgM and OR: 8.78(4.28-17.98) for aβ2GP1 IgM. During about 3 years of follow-up, the smoking patients carrying persistent aPL positivity had the highest cumulative incidence of recurrent myocardial infarction and in-stent restenosis after CAD.

CONCLUSION

The interaction of current smoking and IgM isotype positivity was significantly associated with the increased risk of CAD, including positive aCL IgM and aβ2GP1 IgM. Cigarette smoking elevated the risk of subsequent cardiovascular events in the presence of IgM isotype positivity, including recurrent myocardial infarction and in-stent restenosis.

Determination of Thrombogenicity Levels of Various Antiphospholipid Antibodies by a Modified Thrombin Generation Assay in Patients with Suspected Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is a hypercoagulable state accompanied by the presence of heterogeneous antiphospholipid antibodies (aPL), which nonspecifically affect hemostasis by the presence of lupus anticoagulans (LA), anticardiolipin antibodies (aCL), antibodies against β2-glycoprotein-I (anti-β2GPI), but also non-criteria antibodies such as antibodies against β2-glycoprotein-I domain I (anti-DI), anti-phosphatidylserine/prothrombin (anti-PS/PT), anti-annexin V, and many others. The main target of the antibodies is the activated protein C (APC) system, the elimination of which can manifest itself as a thrombotic complication. The aim of this study was to determine the thrombogenicity of antibodies using a modified protein C-activated thrombin generation assay (TGA) on a group of 175 samples suspected of APS. TGA was measured with/without APC and the ratio of both measurements was evaluated (as for APC resistance), where a cut-off was calculated ≤4.5 (90th percentile) using 21 patients with heterozygous factor V Leiden mutation (FV Leiden heterozygous). Our study demonstrates the well-known fact that multiple positivity of different aPLs is a more severe risk for thrombosis than single positivity. Of the single antibody positivity, LA antibodies are the most serious (p value < 0.01), followed by aCL and their subgroup anti-DI (p value < 0.05). Non-criteria antibodies anti-annexin V and anti-PT/PS has a similar frequency occurrence of thrombogenicity as LA antibodies but without statistical significance or anti-β2GPI1 positivity. The modified TGA test can help us identify patients in all groups who are also at risk for recurrent thrombotic and pregnancy complications; thus, long-term prophylactic treatment is appropriate. For this reason, it is proving increasingly beneficial to include the determination antibodies in combination with modified TGA test.

Solid Phase Assays for Antiphospholipid Antibodies

The diagnosis of antiphospholipid syndrome (APS) relies on the detection of circulating antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are the laboratory criteria if persistently present over time. As aCL and aβ2GPI are two out of the three laboratory criteria, the detection of aPL by solid phase assays is an essential step in the diagnosis of APS. Advancement has been made to resolve some of the methodological challenges of aCL and aβ2GPI assays by providing guidelines how to measure aPL, as well as to gain a better understanding of their diagnostic role. However, solid phase assays for aCL and aβ2GPI still show substantive inter-assay differences, resulting in disagreement concerning positive/negative results, but also differences in titer of antibodies. This hampers the semiquantitative classification into low-medium-high positivity. The non-criteria aPL, such as antibodies against the domain one of β2GPI and anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have roles in confirming the risk in APS, and can be useful, especially in patients with incomplete antibody profiles.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) levels in primary antiphospholipid syndrome. The multicenter ATHERO-APS study

BACKGROUND

The proprotein convertase subtilisin/kexin type 9 (PCSK9) is emerging as a novel cardiovascular risk factor. Levels of PCSK9 in thrombotic primary antiphospholipid syndrome (PAPS) have never been investigated.

METHODS

Cross sectional comparison of baseline characteristics of 91 PAPS patients enrolled in the multicenter prospective ATHERO-APS cohort study. PCSK9 levels were categorized into tertiles and the association with arterial and recurrent thrombosis were assessed by univariable and multivariable logistic regression analysis.

RESULTS

Median age was 51 years and 71.4% (n = 65) were women. Overall, 33% (n = 30) experienced an arterial event while 31% (n = 28) had recurrent thrombotic events. Median PCSK9 levels were 1243 (1100-1650) pg/ml. Patients in the third PCSK9 tertile (>1458 pg/ml) showed a higher prevalence of dyslipidemia, lupus anticoagulant positivity and a history of previous arterial and recurrent thrombosis than patients in the first and second tertile. PCSK9 levels were higher in arterial than venous thrombosis (1502 vs. 1180 pg/ml, p = 0.002), and in patients with recurrent vs isolated thrombosis (1680 vs. 1150 pg/m, p < 0.001). High plasma PCSK9 levels were associated with a 4-fold increase risk for arterial events and with a 10-fold increase risk for recurrent thrombosis after adjustment for confounding factors.

CONCLUSION

These preliminary data suggest that PCSK9 levels are increased in PAPS patients with arterial and recurrent thrombosis. Its role as a possible therapeutic target in PAPS needs further studies.

Mannose Receptor-Mediated Carbon Nanotubes as an Antigen Delivery System to Enhance Immune Response Both In Vitro and In Vivo

Carbon nanotubes (CNTs) are carbon allotropes consisting of one, two, or more concentric rolled graphene layers. These can intrinsically regulate immunity by activating the innate immune system. Mannose receptors (MR), a subgroup of the C-type lectin superfamily, are abundantly expressed on macrophages and dendritic cells. These play a crucial role in identifying pathogens, presenting antigens, and maintaining internal environmental stability. Utilizing the specific recognition between mannose and antigen-presenting cells (APC) surface mannose receptors, the antigen-carrying capacity of mannose-modified CNTs can be improved. Accordingly, here, we synthesized the mannose-modified carbon nanotubes (M-MWCNT) and evaluated them as an antigen delivery system through a series of in vitro and in vivo experiments. In vitro, M-MWCNT carrying large amounts of OVA were rapidly phagocytized by macrophages and promoted macrophage proliferation to facilitate cytokines (IL-1β, IL-6) secretion. In vivo, in mice, M-MWCNT induced the maturation of dendritic cells and increased the levels of antigen-specific antibodies (IgG, IgG1, IgG2a, IgG2b), and cytokines (IFN-γ, IL-6). Taken together, M-MWCNT could induce both humoral and cellular immune responses and thereby can be utilized as an efficient antigen-targeted delivery system.

Emerging Molecular Markers Towards Potential Diagnostic Panels for Lupus

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease which can affect various tissues and organs, posing significant challenges for clinical diagnosis and treatment. The etiology of SLE is highly complex with contributions from environmental factors, stochastic factors as well as genetic susceptibility. The current criteria for diagnosing SLE is based primarily on a combination of clinical presentations and traditional lab testing. However, these tests have suboptimal sensitivity and specificity. They are unable to indicate disease cause or guide physicians in decision-making for treatment. Therefore, there is an urgent need to develop a more accurate and robust tool for effective clinical management and drug development in lupus patients. It is fortunate that the emerging Omics have empowered scientists in the discovery and identification of potential novel biomarkers of SLE, especially the markers from blood, urine, cerebrospinal fluids (CSF), and other bodily fluids. However, many of these markers have not been carefully validated for clinical use. In addition, it is apparent that individual biomarkers lack sensitivity or specificity. This review summarizes the sensitivity, specificity and diagnostic value of emerging biomarkers from recent studies, and discusses the potential of these markers in the development of biomarker panel based diagnostics or disease monitoring system in SLE.

Cardiac and vascular features of arterial and venous primary antiphospholipid syndrome. The multicenter ATHERO-APS study

BACKGROUND

Patients with primary antiphospholipid syndrome (PAPS) may suffer from venous and/or arterial thrombosis, but studies addressing eventual clinical and laboratory features that may discriminate between arterial thromboembolism (ATE) from venous thromboembolism (VTE) have been poorly addressed.

METHODS

Cross sectional comparison of baseline characteristics of 100 patients enrolled in the multi center ATHERO-APS cohort study; patients with previous ATE and VTE were compared with regards to clinical and biochemical variables as well as to echocardiographic features and ankle-brachial index (ABI) measured at enrolment.

RESULTS

Mean age of patients was 51 years, 72 were women. 60 patients suffered VTE and 40 ATE. Compared to VTE, ATE patients displayed a higher prevalence of hypertension (43.3% vs. 65%, p = 0.034) and diabetes (3.3% vs. 17.5%, p = 0.015). Mean concentration of inflammation and complement activation markers were similar between the two groups as well as autoantibodies titres; mean D-dimer concentration was greater in VTE patients (184 ng/ml vs. 347 ng/ml; p = 0.024) whereas mean platelet count was greater in ATE patients (263 × 10⁹/L vs 216 × 10⁹/L, p = 0.044). By multivariable logistic regression analysis, adjusted for age, sex, hypertension and diabetes, ABI ≤ 0.9 (OR: 3.4; p = 0.041) and left atrial enlargement (OR: 3.5; p = 0.035) were associated with a history of ATE. ATE patients had a higher prevalence of ABI <0.9 (32.5% vs 10% p = 0.005) than VTE patients. At logistic regression analysis, IgG aCL >120 GPL U/ml was associated with an ABI ≤0.9 (OR: 5; p = 0.023) after adjustment for age and sex.

CONCLUSION

Clinical, laboratory and cardiovascular variables distinguish arterial from venous APS patients, amongst which the ABI and left atrial enlargement. Implications for these two distinct clinical phenotypes of APS patients need further investigation.

Role of antiphospholipid antibodies in the diagnosis of antiphospholipid syndrome

The diagnosis of antiphospholipid syndrome (APS) relies on the detection of antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LA), anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are included as laboratory criteria, if persistently present. LAC measurement remains a complicated procedure with many pitfalls and interfered by anticoagulant therapy. Solid-phase assays for aCL and aβ2GPI show interassay differences. These methodological issues make the laboratory diagnosis of APS challenging. In the interpretation of aPL results, antibody profiles help in identifying patients at risk. Other aPL, such as antibodies against the domain I of beta2-glycoprotein (aDI) and antiphosphatidylserine-prothrombin (aPS/PT) antibodies have been studied in the last years and may be useful in risk stratification of APS patients. Because of the methodological shortcomings of immunological and clotting assays, these non-criteria aPL may be useful in patients with incomplete antibody profiles to confirm or exclude the increased risk profile. This manuscript will focus on the laboratory aspects, the clinical relevance of assays and interpretation of aPL results in the diagnosis of APS.

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The presence of antiphospholipid antibodies (aPL) define the diagnosis of the antiphospholipid syndrome (APS).

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Laboratory criteria are lupus anticoagulant, anticardiolipin (aCL), and antibeta2-glycoprotein I antibodies (aβ2GPI) IgG/IgM.

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Lupus anticoagulant measurement, as well as solid phase assays for aCL and aβ2GPI, show methodological challenges.

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Antibodies against domain I of β2GPI (aDI) and antiphosphatidylserine-prothrombin (aPS/PT) antibodies are non-criteria aPL.

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aDI and aPS/PT may be useful in risk stratification of APS patients.

Systematic review and meta-analysis of cardiovascular risk in rheumatological disease: Symptomatic and non-symptomatic events in rheumatoid arthritis and systemic lupus erythematosus

Although each autoimmune disease is associated with specific tissue or organ damage, rheumatic diseases share a pro-inflammatory pattern that might increase cardiovascular risk. Retrospective and prospective studies on patients affected by systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) highlighted the concept of "accelerated atherosclerosis". Therefore, the purpose of this systematic review and meta-analysis is the assessment of symptomatic or asymptomatic cardiovascular events among patients with rheumatic diseases as RA and SLE. The literature research obtained all manuscripts published in the English language between 2015 and 2019 for a total of 2355 manuscripts. After selection through inclusion and exclusion criteria, four articles examined cardiovascular risk in RA patients, 8 in SLE patients, and 2 in RA and SLE patients. Patients with SLE had a RR of 1.98 (95% CI: 1.18-3.31) of symptomatic cardiovascular events compared to the unexposed cohort. The meta-regression analysis showed that younger patient (age per year increase β = -0.12 95%CI: -0.20, -0.4), belonging to studies conducted in continent different from America (β = -0.89; -95% CI: 1.67, -0.10), after 2000 (β = 0.87; 95% CI: 0.09, 1.65) and with a higher quality score 0.80 (95% CI: 0.31, 1.29) had a higher risk of cardiovascular events. In patients with RA, the RR of cardiovascular events was 1.55 (95% CI: 1.18-2.02). These data are helpful to implement cardiovascular preventive strategies among people suffering from rheumatologic diseases to decrease the incidence of cardiovascular events. However, these implementation needs to build a higher network between rheumatologists and primary care healthcare workers to furnish the same information to patients and monitor their preventive practice compliance.

Use of Direct Oral Anticoagulants in Patients With Antiphospholipid Syndrome: A Systematic Review and Comparison of the International Guidelines

Antiphospholipid antibody syndrome (APS) requires long-term anticoagulation to prevent recurrent thrombosis. Direct oral anticoagulants (DOACs) have been increasingly used in APS patients, but contradictory guidelines recommendations on their use do exist. We performed a systematic review of literature including studies investigating the role of DOACs in APS patients. At this aim, PubMed and Cochrane databases were searched according to PRISMA guidelines. We identified 14 studies which investigated the use of DOACs in patients with APS, of which 3 randomized clinical trials (RCTs), 1 post-hoc analysis of 3 RCTs, 7 case series and 3 cohort studies (2 prospective and 1 retrospective). Among DOACs, rivaroxaban was the most used (n = 531), followed by dabigatran (n = 90) and apixaban (n = 46). Regarding guidelines indications, the 2019 European Society of Cardiology (ESC) and American Society of Hematology (ASH) guidelines recommend against the use of DOACs in all APS patients. The European League Against Rheumatism (EULAR), British Society for Haematology (BSH), and International Society on Thrombosis and Haemostasis (ISTH) guidance provided more detailed indications stating that warfarin should be the first-choice treatment but DOACs may be considered in patients (1) already on a stable anticoagulation with a DOAC, (2) with low-quality anticoagulation by warfarin, (3) unwilling/unable to undergo INR monitoring, (4) with contraindications or serious adverse events under warfarin. Patients with arterial APS or triple positivity should be treated with warfarin while venous APS with single or double positivity may be candidate to DOACs, but high-quality studies are needed.

Antiphospholipid Antibodies and Heart Failure with Preserved Ejection Fraction. The Multicenter ATHERO-APS Study

Background. The prevalence of heart failure with preserved ejection fraction (HFpEF) in patients with antiphospholipid syndrome (APS) is unknown. Methods. A prospective multicenter cohort study including 125 patients was conducted: 91 primary APS (PAPS), 18 APS-SLE, and 16 carriers. HFpEF was diagnosed according to the 2019 European Society of Cardiology criteria: patients with ≥5 points among major and minor functional and morphological criteria including NT-ProBNP > 220 pg/mL, left atrial (LA) enlargement, increased left ventricular filling pressure. Results. Overall, 18 (14.4%) patients were diagnosed with HFpEF; this prevalence increased from 6.3% in carriers to 13.2% in PAPS and 27.8% in APS-SLE. Patients with HFpEF were older and with a higher prevalence of hypertension and previous arterial events. At logistic regression analysis, age, arterial hypertension, anticardiolipin antibodies IgG > 40 GPL (odds ratio (OR) 3.43, 95% confidence interval (CI) 1.09–10.77, p = 0.035), anti β-2-glycoprotein-I IgG > 40 GPL (OR 5.28, 1.53–18.27, p = 0.009), lupus anticoagulants DRVVT > 1.25 (OR 5.20, 95% CI 1.10–24.68, p = 0.038), and triple positivity (OR 3.56, 95% CI 1.11–11.47, p = 0.033) were associated with HFpEF after adjustment for age and sex. By multivariate analysis, hypertension (OR 19.49, 95% CI 2.21–171.94, p = 0.008), age (OR 1.07, 95% CI 1.00–1.14, p = 0.044), and aβ2GPI IgG > 40 GPL (OR 8.62, 95% CI 1.23–60.44, p = 0.030) were associated with HFpEF. Conclusion. HFpEF is detectable in a relevant proportion of APS patients. The role of aPL in the pathogenesis and prognosis of HFpEF needs further investigation.

Location of recurrent cardiovascular events and anticardiolipin antibodies

BACKGROUND

The relationship between anticardiolipin (aCL) antibodies and cardiovascular events is uncertain and may vary according to arterial location.

MATERIALS AND METHODS

FRENA is an ongoing registry of stable outpatients with symptomatic coronary artery disease (CAD), cerebrovascular disease (CVD) or peripheral artery disease (PAD). The rate of subsequent ischaemic events was cross-referenced with the presence of aCL antibodies (any isotype, IgG or IgM).

RESULTS

As of June 2017, 1387 stable outpatients were recruited. Of these, 120 (8.7%) showed positive levels of aCL antibodies. Over an average follow-up of 18 months, 250 patients developed subsequent events: 101 myocardial infarction, 57 ischaemic stroke and 92 critical leg events. Patients with positive aCL antibodies had a higher risk of distal artery events (a composite of ischaemic stroke or critical leg events) than patients with undetectable or low levels (rate ratio: 1.66; 95% CI: 1.07-2.60). However, an association with central coronary events was not found. The multivariate Cox analysis after adjustment for relevant clinical covariates showed that positivity of aCL antibodies is an independent risk factor for distal events (hazard ratio: 1.60; 95% CI: 1.01-2.55; P < .05).

CONCLUSIONS

Positivity of aCL antibodies is associated with an increased risk of subsequent distal artery ischaemic events (cerebral or leg arteries) but not coronary artery events. Anticardiolipin antibodies appear to have a different relationship on the localisation of ischaemic events in patients with symptomatic artery disease.

16th International congress on antiphospholipid antibodies task force report on clinical manifestations of antiphospholipid syndrome

The objectives of the 16th International Congress on Antiphospholipid Antibodies (aPL) Task Force on Clinical Manifestations of Antiphospholipid Syndrome (APS) were to critically analyze: a) the definition of "APS"; b) the current knowledge on non-traditional manifestations associated with aPL; and c) the risk stratification strategies in aPL-positive patients. The quality of evidence was assessed by the GRADE system. The task force concluded that: a) APS does not have a uniform definition given the heterogeneity of the clinical presentations and different aPL profiles; b) current literature supports the role for aPL testing in cases of thrombocytopenia and recurrent cardiac events but are limited by vast heterogeneity, providing an overall low-to-very low level of evidence; and c) risk stratification strategies in aPL-positive patients, such as aPL-Score and Global APS Score, can be useful in clinical practice. International multicenter studies are still highly needed to improve the quality of available evidence and consequently the strength of future recommendations.

VWF, Platelets and the Antiphospholipid Syndrome

The antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with the persistent presence of antiphospholipid antibodies (aPLs). Laboratory criteria for the classification of APS include the detection of lupus anticoagulant (LAC), anti-cardiolipin (aCL) antibodies and anti-β2glycoprotein I (aβ2GPI) antibodies. Clinical criteria for the classification of thrombotic APS include venous and arterial thrombosis, along with microvascular thrombosis. Several aPLs, including LAC, aβ2GPI and anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have been associated with arterial thrombosis. The Von Willebrand Factor (VWF) plays an important role in arterial thrombosis by mediating platelet adhesion and aggregation. Studies have shown that aPLs antibodies present in APS patients are able to increase the risk of arterial thrombosis by upregulating the plasma levels of active VWF and by promoting platelet activation. Inflammatory reactions induced by APS may also provide a suitable condition for arterial thrombosis, mostly ischemic stroke and myocardial infarction. The presence of other cardiovascular risk factors can enhance the effect of aPLs and increase the risk for thrombosis even more. These factors should therefore be taken into account when investigating APS-related arterial thrombosis. Nevertheless, the exact mechanism by which aPLs can cause thrombosis remains to be elucidated.

Antiphospholipid Antibodies in Sickle Cell Disease: A Systematic Review and Exploratory Meta-Analysis

The relationship between antiphospholipid antibodies (aPL) and sickle cell disease (SCD) has never been systematically addressed. Our aim was to evaluate potential links between SCD and aPL in all age groups. EMBASE/PubMed was screened from inception to May 2020 and Peto odds ratios for rare events were calculated. The pooled prevalence (PP) of IgG anticardiolipin antibodies (aCL) was higher in individuals with SCD than in controls (27.9% vs 8.7%, P < 0.0001), that of IgM aCL was similar in the two groups (2.9% vs 2.7%); only individuals with SCD were positive for lupus anticoagulant (LA) (7.7% vs 0%, P < 0.0001). The PP of leg ulcers was similar between aPL positive and negative individuals (44% vs 53%) and between patients in acute crisis and stable patients (5.6% vs 7.3%). Reporting of aPL as a binary outcome and not as a titer precluded further interpretation. The results indicate that a prospective case-control study with serial measurements of a panel of aPL in SCD patients might be warranted, in order to understand further the possible pathogenic role of aPL in SCD.

Antiphospholipid antibodies and lower extremity peripheral artery disease: A systematic review and meta-analysis

AIM

To evaluate the clinical relevance of antiphospholipid antibodies (aPL) in patients with lower extremity peripheral artery disease (PAD).

DATA SOURCES

EMBASE and MEDLINE databases were searched from inception to March 2020 for clinical studies reporting on the association between of aPL [IgG/IgM anticardiolipin (aCL) and lupus anticoagulant (LA)] and PAD.

METHODS

We determined the pooled prevalence (PP) of patients positive for aPL in PAD or the PP of PAD in patients positive for aPL; we employed Peto's odds ratio with random effect for the meta-analysis.

RESULTS

Twenty-one studies comprising 6,057 patients were evaluated: in patients with PAD, the PP of IgG aCL was 12% vs 4.1% in those without, IgM aCL was 13.2% vs 2.1%, and LA 13.3% vs 3.3%, respectively. The PP of patients with LA was greater in critical limb ischemia than in the control group (19.3% vs 4.2%). Also, the PP of patients with LA was greater in the failed than in the successful revascularisation group (35.8% vs 15.8%). The PP of post-procedural revascularisation failures was similar in the groups given or not given oral anticoagulation (59.2% vs 61.9%).

CONCLUSION

All the aPL related to PAD regardless of diagnostic definition used, whereas LA related also to critical limb ischaemia and failed revascularisation. Data expressed as percentage of participants positive for aPL limit the interpretation of these relationships.

Evaluation of novel assays for the detection of autoantibodies in antiphospholipid syndrome

Patients with antiphospholipid syndrome (APS) present with clinical features of recurrent thrombosis and pregnancy morbidity and persistently test positive for the presence of antiphospholipid antibodies (aPL). At least one clinical (vascular thrombosis or pregnancy morbidity) and one lab-based (positive test result for lupus anticoagulant, anticardiolipin antibodies and/or anti-β2-glycoprotein 1 antibodies) criterion have to be met for a patient to be classified as having APS. Nevertheless, the clinical variety of APS encompasses additional signs and symptoms, potentially affecting any organ, that cannot be explained exclusively by a prothrombotic state. Those manifestations, also known as extra-criteria manifestations, include haematologic (thrombocytopenia and haemolytic anaemia), neurologic (chorea, myelitis and migraine) manifestations as well as the presence of livedo reticularis, nephropathy and valvular heart disease. The growing body of evidence describing the clinical aspect of the syndrome has been paralleled over the years by emerging research interest focusing on the development of novel biomarkers that might improve the diagnostic accuracy for APS when compared to the current aPL tests. This review will focus on the clinical utility of extra-criteria aPL specificities. Besides, the promising role of a new technology using particle based multi-analyte testing that supports aPL panel algorithm testing will be discussed. Diagnostic approaches to difficult cases, including real-world case studies investigating the diagnostic added value of extra criteria aPL, particularly anti-phosphatidylserine/prothrombin, will also be examined.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

The antiphospholipid syndrome - often overlooked cause of vascular occlusions?

The antiphospholipid syndrome (APS) was fully recognized as a clinical entity in the early 1980s. Still, more than 30 years later, the epidemiology of APS is not well described, and furthermore, APS remains a challenge in terms of both diagnostic issues and clinical praxis involving a wide range of specialties. To date, there are no diagnostic criteria for APS. The present classification criteria rely on a combination of clinical manifestations and persistently positive tests for antiphospholipid antibodies (aPL). Clinical symptoms comprise vascular thrombosis, which can affect any vascular bed, including venous, microvascular and arterial vessels, and a set of pregnancy morbidities including early and late miscarriages, foetal death and preeclampsia. APS is more frequent among patients with other autoimmune diseases, and it is especially common in systemic lupus erythematosus (SLE). Importantly, APS symptoms can present in almost any medical specialty, but general knowledge and most previous clinical studies have essentially been confined to haematology, rheumatology and obstetrics/gynaecology. However, recent data demonstrate a relatively high prevalence of aPL also in patients from the general population who suffer from vascular occlusions or pregnancy complications. It is important that these patients are recognized by the general health care since APS is a treatable condition. This review aims to summarize the present knowledge on the history, pathogenesis, clinical manifestations and treatment of APS in order to urge a wide range of clinicians to consider comprehensive assessment of all patients where the diagnosis APS may be conceivable.

Seronegative antiphospholipid syndrome: refining the value of "non-criteria" antibodies for diagnosis and clinical management

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by arterial and venous thrombotic manifestations and/or pregnancy-related complications in patients with persistently high antiphospholipid antibodies (aPL), the most common being represented by anticardiolipin antibodies (aCL), anti-beta 2 glycoprotein-I (aβ2GPI), and lupus anticoagulant (LAC). A growing number of studies have showed that, in some cases, patients may present with clinical features of APS but with temporary positive or persistently negative titers of aPL. For these patients, the definition of seronegative APS (SN-APS) has been proposed. Nevertheless, the negativity to classic aPL criteria does not imply that other antibodies may be present or involved in the onset of thrombosis. The diagnosis of SN-APS is usually made by exclusion, but its recognition is important to adopt the most appropriate anti-thrombotic strategy to reduce the rate of recurrences. This research is in continuous development as the clinical relevance of these antibodies is far from being completely clarified. The most studied antibodies are those against phosphatidylethanolamine, phosphatidic acid, phosphatidylserine, phosphatidylinositol, vimentin/cardiolipin complex, and annexin A5. Moreover, the assays to measure the levels of these antibodies have not yet been standardized. In this review, we will summarize the evidence on the most studied non-criteria aPL, their potential clinical relevance, and the antithrombotic therapeutic strategies available in the setting of APS and SN-APS.