Impaired brachial endothelial function in patients with primary anti-phospholipid syndrome

Non-invasive imaging in antiphospholipid syndrome to assess subclinical coronary artery disease

Antiphospholipid antibody syndrome (usually named antiphospholipid syndrome, APS) is an autoimmune disorder seen mainly in young people. Clinically, APS is described by pregnancy complications and/or a hypercoagulable state, including the venous or arterial vasculature, and strongly related to antiphospholipid antibodies. Although several cardiac manifestations have been involved with APS, and accelerated atherosclerosis is present in this condition, little is known about cardiovascular (CV) risk and the relation between APS. Several studies have used imaging markers to associate them with the main clinical features of patients with APS and the probability of having subclinical atherosclerosis. However, it has not yet been established which markers are most related to the risk of developing CV diseases (CVD) in these patients. In this narrative review, we focus on non-invasive imaging markers that can predict CVD, including carotid intima-media thickness and carotid plaques assessed by carotid ultrasonography or coronary artery calcium score, which usually by computed tomography. We also examine the evidence about vascular function markers used in APS, such as arterial flow-mediated brachial dilation and artery stiffness measured by the velocity of the pulse wave. We present the current status of non-invasive imaging markers, which suggest the existence of subclinical atherosclerosis in patients with APS. However, new prospective research is required to identify the predictive value of these findings and their modification by current treatments for APS.

Hydroxychloroquine reverses the prothrombotic state in a mouse model of antiphospholipid syndrome: Role of reduced inflammation and endothelial dysfunction

Antiphospholipid antibodies (aPL) promote endothelial dysfunction, inflammation and procoagulant state. We investigated the effect of hydroxychloroquine (HCQ) on prothrombotic state and endothelial function in mice and in human aortic endothelial cells (HAEC). Human aPL were injected to C57BL/6 mice treated or not with HCQ. Vascular endothelial function and eNOS were assessed in isolated mesenteric arteries. Thrombosis was assessed both in vitro by measuring thrombin generation time (TGT) and tissue factor (TF) expression and in vivo by the measurement of the time to occlusion in carotid and the total thrombosis area in mesenteric arteries. TGT, TF, and VCAM1 expression were evaluated in HAEC. aPL increased VCAM-1 expression and reduced endothelium dependent relaxation to acetylcholine. In parallel, aPL shortened the time to occlusion and extended thrombus area in mice. This was associated with an overexpression of TF and an increased TGT in mice and in HAEC. HCQ reduced clot formation as well as TGT, and improved endothelial-dependent relaxations. Finally, HCQ increased the p-eNOS/eNOS ratio. This study provides new evidence that HCQ improves procoagulant status and vascular function in APS by modulating eNOS, leading to an improvement in the production of NO.

Vascular Manifestations in Antiphospholipid Syndrome (APS): Is APS a Thrombophilia or a Vasculopathy?

PURPOSE OF REVIEW

Antiphospholipid antibody syndrome (APS) is characterized primarily by thrombosis and pregnancy morbidity. Chronic vascular lesions can also occur. While the underlying mechanisms of these vascular lesions are not entirely known, there have been multiple theories describing the potential process of vasculopathy in APS and the various clinical manifestations associated with it.

RECENT FINDINGS

Recently, it has been demonstrated that endothelial proliferation in kidneys can be explained by the activation of the mammalian target of rapamycin complex (mTORC) pathway by antiphospholipid antibodies (aPL). These data support the existence of an APS-related vasculopathy in different locations which can explain-in part-the different manifestations of APS. This review focuses on the various manifestations of APS as a result of APS-related vasculopathy, as well as pathophysiology, current screening, and treatment options for clinicians to be aware of.

Lipid peroxidation as risk factor for endothelial dysfunction in antiphospholipid syndrome patients

The aim of this study was to evaluate oxidative stress markers and it relations to endothelial damage as risk factor for thrombosis in patients with primary (PAPS) and secondary (SAPS) antiphospholipid syndrome (APS) in correlation to traditional risk factors. Flow-mediated (FMD) and nitroglycerine (NMD)-induced dilation of the brachial artery were studied in 140 APS patients (90 PAPS, 50 SAPS) and 40 controls matched by age, sex, and conventional risk factors for atherosclerosis. Markers of oxidative stress, lipid hydroperoxydes (LOOH), advanced oxidation protein products (AOPP), total sulfhydryl groups (tSHG), and paraoxonase 1 activity (PON1) were determined by spectrophotometric method. Oxidative stress dominates in APS patients. LOOH and AOPP correlate to lipid fractions (p < 0.05), unlike PON1, tSHG that correlated to antiphospholipid antibody positivity (p < 0.05). FMD was lower in APS patients comparing to controls (p < 0.001). Cholesterol is independent variable for FMD impairment in control group (p = 0.011); LOOH in PAPS (p = 0.004); LOOH, aCL, and triglycerides in SAPS patients (p = 0.009, p = 0.049, and p = 0.012, respectively). Combined predictive of aCL and LOOH is better for FMD impairment than LOOH alone in both PAPS and SAPS patients (AUC 0.727, p = 0.001, 95 % CI 0.616-0.837 and AUC 0.824, p˂0.001, 95 % CI 0.690-0.957, respectively). Lipid peroxidation is independent predictor for endothelial dysfunction in APS patients. We demonstrated synergistic effect of aCL and LOOH as risk for endothelial impairment in both PAPS and SAPS patients.

Primary antiphospholipid syndrome: absence of premature atherosclerosis in patients without traditional coronary artery disease risk factors

OBJECTIVE

To investigate if patients with Primary Antiphospholipid Syndrome (PAPS) with venous and/or arterial thrombosis without traditional coronary artery disease (CAD) risk factors develop early atherosclerotic vascular damage.

METHODS

27 female patients with PAPS (Sidney criteria) and 27 age, body mass index (BMI), and sex matched controls were consecutively selected. Exclusion criteria were: black race, age ≥55 years, traditional cardiovascular risk factors, other thrombophilias or connective tissue diseases, corticosteroids use and pregnancy. All subjects underwent Pulse Wave Velocity (PWV) and Echo-Tracking (ET), both in carotidal bed, to analyse vascular functional properties.

RESULTS

Age (p = 0.92) and BMI (p = 0.91) were comparable in both groups. PAPS patients and controls had similar PWV (9.07 ± 1.08 m/s vs 9.42 ± 1.47 m/s, p = 0.34) as well as echo tracking parameters such as intima-media thickness (683 ± 171 µm vs 636 ± 140 µm, p = 0.52), carotideal diameter (p = 0.26), distensibility (p = 0.92), compliance coefficients (p = 0.36) and elastic modulus (p = 0.78). Patients with exclusively venous thrombosis showed lower PWV than patients with arterial thrombosis (8.55 ± 0.70 m/s vs 9.56 ± 0.94 m/s, p = 0.01), but no difference regarding intima-media thickness (683 ± 171 µm vs 636 ± 140 µm, p = 0.52) was observed.

CONCLUSION

Patients with PAPS do not seem to be at higher risk of developing premature atherosclerosis. Patients who suffered exclusively venous thrombosis seem to be at lower risk than those with exclusively arterial events. Other studies need to confirm our findings.

Role of Toll-like receptors 2 and 4 in mediating endothelial dysfunction and arterial remodeling in primary arterial antiphospholipid syndrome

OBJECTIVE

To assess the role of Toll-like receptors (TLRs) in antiphospholipid antibody (aPL)-mediated vascular abnormalities in patients with primary arterial antiphospholipid syndrome (APS).

METHODS

Forty-eight subjects participated in the study. Arterial function and structure and TLR pathway activation were determined in patients with primary arterial APS and matched controls. The pathogenic effects of aPL isolated from patients were assessed in wild-type (WT) and TLR-knockout mice.

RESULTS

APS patients had endothelial dysfunction, arterial stiffening, and hypertrophy, as evidenced by decreased brachial artery endothelium-dependent flow-mediated dilation (FMD) and increased aortic pulse wave velocity and carotid intima-media thickness (IMT), as compared with controls. Plasma samples from APS patients revealed decreased nitric oxide (NO) availability and a pro-oxidative, proinflammatory, and prothrombotic state illustrated by a decrease in nitrite and an increase in lipid peroxidation, tumor necrosis factor α levels, and tissue factor (TF) levels. Furthermore, TLR pathway activation was found in APS patients with increased TLR-2 and TLR-4 messenger RNA expression and increased protein levels of the activated TLR transduction protein interleukin-1 receptor-associated kinase 1 in peripheral blood mononuclear cells. Moreover, agonist-stimulated cell-surface expression of TLR-2 and TLR-4 in circulating monocytes was higher in APS patients than in controls. These changes were positively associated with IMT and negatively associated with FMD. Finally, aPL injection decreased mesenteric endothelium-dependent relaxation and increased TF expression in WT mice but not in TLR-2- or TLR-4-knockout mice.

CONCLUSION

This translational study supports the notion that TLR-2 and TLR-4 play a role in mediating vascular abnormalities in patients with primary arterial APS. TLRs thus constitute a promising pharmacologic target for preventing cardiovascular complications in APS.

Decreased flow-mediated dilatation with increased arterial stiffness and thickness as early signs of atherosclerosis in polymyositis and dermatomyositis patients

Several autoimmune rheumatic diseases have been associated with accelerated atherosclerosis or other different types of vasculopathy depending on the underlying disease, leading to increased cardio- and cerebrovascular disease risk. Polymyositis (PM) and dermatomyositis (DM), members of idiopathic inflammatory myopathies (IIMs), a group of systemic autoimmune diseases are also associated with elevated risk of cardiovascular diseases (CVD). Up until now, no specific data is known on the mechanisms, risk factors, or possible vasculopathy leading to increased CVD risk. The aims of the present study were to assess the flow-mediated dilatation of the brachial artery by a TensioClinic arteriograph and to measure the thickness of carotid artery intima-media, the augmentation index, and the pulse wave velocity using high-resolution ultrasonography in a cohort of PM and DM patients. We also investigated the correlation of these parameters with the traditional risk factors of atherosclerosis and overall cardiovascular status within PM and DM patients. Twenty-seven patients (21 females, six males) with IIMs were enrolled in this study, and 38 healthy individuals matched for sex and age served as controls. We found a decreased flow-mediated dilatation in the brachial artery (6.36 vs. 8.39 %) with increased arterial stiffness and carotid artery thickness in our patients compared to healthy controls. We found significantly decreased flow-mediated dilatation of the brachial artery (5.57 vs. 8.39 %) in DM patients. We also detected a correlation between these parameters and the traditional cardiovascular risk factors, as well as hypertriglyceridemy, hypertension, and peripheral arterial disease. In DM, overall, more vascular abnormalities were found than in PM. Our findings suggest that flow-mediated dilatation of the brachial artery, arterial stiffness, and carotid artery thickness measurements could be beneficial for predicting the CVD risk in myositis patients. Further investigations need to find the potential differences and role of inflammation and immune mechanisms in atherosclerotic processes in DM and PM.

[Assessment of endothelial function in autoimmune diseases]

Numerous autoimmune-inflammatory rheumatic diseases have been associated with accelerated atherosclerosis or other types of vasculopathy leading to an increase in cardiovascular disease incidence. In addition to traditional cardiovascular risk factors, endothelial dysfunction is an important early event in the pathogenesis of atherosclerosis, contributing to plaque initiation and progression. Endothelial dysfunction is characterized by a shift of the actions of the endothelium toward reduced vasodilation, a proinflammatory and a proadhesive state, and prothrombic properties. Therefore, assessment of endothelial dysfunction targets this vascular phenotype using several biological markers as indicators of endothelial dysfunction. Measurements of soluble adhesion molecules (ICAM-1, VCAM-1, E-selectin), pro-thrombotic factors (thrombomodulin, von Willebrand factor, plasminogen activator inhibitor-1) and inflammatory cytokines are most often performed. Regarding the functional assessment of the endothelium, the flow-mediated dilatation of conduit arteries is a non-invasive method widely used in pathophysiological and interventional studies. In this review, we will briefly review the most relevant information upon endothelial dysfunction mechanisms and explorations. We will summarize the similarities and differences in the biological and functional assessments of the endothelium in different autoimmune diseases.

Antiphospholipid antibodies promote leukocyte-endothelial cell adhesion and thrombosis in mice by antagonizing eNOS via β2GPI and apoER2

In antiphospholipid syndrome (APS), antiphospholipid antibodies (aPL) binding to β2 glycoprotein I (β2GPI) induce endothelial cell-leukocyte adhesion and thrombus formation via unknown mechanisms. Here we show that in mice both of these processes are caused by the inhibition of eNOS. In studies of cultured human, bovine, and mouse endothelial cells, the promotion of monocyte adhesion by aPL entailed decreased bioavailable NO, and aPL fully antagonized eNOS activation by diverse agonists. Similarly, NO-dependent, acetylcholine-induced increases in carotid vascular conductance were impaired in aPL-treated mice. The inhibition of eNOS was caused by antibody recognition of domain I of β2GPI and β2GPI dimerization, and it was due to attenuated eNOS S1179 phosphorylation mediated by protein phosphatase 2A (PP2A). Furthermore, LDL receptor family member antagonism with receptor-associated protein (RAP) prevented aPL inhibition of eNOS in cell culture, and ApoER2-/- mice were protected from aPL inhibition of eNOS in vivo. Moreover, both aPL-induced increases in leukocyte-endothelial cell adhesion and thrombus formation were absent in eNOS-/- and in ApoER2-/- mice. Thus, aPL-induced leukocyte-endothelial cell adhesion and thrombosis are caused by eNOS antagonism, which is due to impaired S1179 phosphorylation mediated by β2GPI, apoER2, and PP2A. Our results suggest that novel therapies for APS can now be developed targeting these mechanisms.

Atherosclerosis in primary antiphospholipid syndrome

Antiphospholipid syndrome (APS) is the most common cause of acquired thrombophilia, but experimental and clinical evidence accumulated over the years suggest that the clinical manifestations of APS go beyond those of a simple hypercoagulable state. Although still a controversial topic, the elevated risk of atherosclerosis in systemic lupus erythematosus seems little accounted for by the presence of antiphospholipid antibodies, whereas premature atherosclerosis has been addressed in few series of patients with primary APS. The available data in primary APS suggest that traditional risk factors for atherosclerosis are less involved in arterial disease, rather antiphospholipid antibodies appear as major players. Their effect on the coagulation system, the vessel wall and on the antioxidant/oxidant balance impairs vascular homeostasis, leading to premature arterial thickening.

Patients with antiphospholipid syndrome display endothelial perturbation

BACKGROUND

There is strong evidence that antiphospholipid antibodies (aPL) perturb endothelium both in vitro and in experimental animal models. by inducing a vasculopathy and an endothelial pro-inflammatory/coagulant phenotype. However, few contrasting studies raised the issue about the possibility to detect a comparable endothelial perturbation in anti-phospholipid syndrome (APS) patients. The aim of this observational case-control study was to evaluate several parameters of endothelial perturbation in patients with APS and without any other atherosclerosis risk factor.

PATIENTS AND METHODS

We investigated plasma levels of soluble adhesion molecules (s-ICAM-1, s-VCAM-1, s-E-selectin), soluble thrombomodulin (sTM), von Willebrand factor (vWF) and tissue plasminogen activator (t-PA) by solid-phase assays in 40 selected APS patients and 40 age- and sex-matched healthy subjects. In addition, we evaluated circulating endothelial cells by flow cytometry and brachial artery flow-mediated vasodilation. Patients and controls were free of conditions known to affect both the biological and the functional endothelial parameters.

RESULTS

Plasma levels of sTM, s-E-selectin and s-VCAM-1 did not differ from controls, while a significant increase in s-ICAM-1 (P = 0.029), t-PA (P = 0.003) and vWF titres (P = 0.002) was found. Circulating mature endothelial cells were also significantly higher in patients than in controls (P = 0.05) and decreased during both vitamin K antagonists (P = 0.001) and antiplatelet (P = 0.032) treatments. Mean brachial artery flow-mediated vasodilation responses were significantly impaired compared to healthy subjects (P = 0.0001).

CONCLUSIONS

As a whole these findings indicate that APS patients display an endothelial perturbation in the absence of other detectable traditional risk factors for atherosclerosis.

Patients with primary antiphospholipid antibody syndrome and without associated vascular risk factors present a normal endothelial function

INTRODUCTION

Primary antiphospholipid antibody syndrome (PAPS) is characterized by venous or arterial thrombosis and positive antiphospholipid antibodies. It is controversial whether PAPS patients have early atherosclerosis. Endothelial dysfunction is an early event in the natural history of atherosclerosis. Aim of our study was to compare endothelial function of patients with PAPS and no associated risk factors with that of age- and sex-matched controls.

MATERIALS AND METHODS

Patients with PAPS, carefully selected to exclude all known risk factors for cardiovascular diseases, estrogen therapy, pregnancy, intake of drugs affecting endothelial function, vitamins or antioxidants, were included in a case-control study. Controls were age- (+/-5 years) and sex-matched subjects with the same exclusion criteria but without PAPS. Flow-mediated dilation of the brachial artery and some plasmatic markers of endothelial and platelet activation were measured. Measures are expressed as mean+/-SEM.

RESULTS

Twenty cases (mean age 42+/-4.0 years, 11 females) and 39 controls (mean age 41+/-2.9, 22 females) were studied. FMD was 5.7+/-0.8% in cases (95% CI: 4.1 to 7.3) and 6.8+/-0.5% (5.7 to 7.9) in controls (p=NS). Plasma von Willebrand factor was 128+/-11.3% and 134.2+/-16.1% in cases and controls, respectively (p=NS). Soluble P-selectin and soluble CD40L were 94.1+/-4.9 ng/ml and 0.7+/-0.1 ng/ml in cases and 87.7+/-4.0 ng/ml and 1.0+/-0.2 in controls, respectively (p=NS). In a substudy, circulating progenitor and mature endothelial cells were comparable between the two groups.

CONCLUSIONS

Endothelial function in patients with PAPS and no associated risk factors is similar to that of age- and sex- matched controls. These data suggest that the alterations leading to thrombosis in PAPS concern primarily the clotting system.

Endothelial dysfunction in patients with antiphospholipid syndrome assessed with positron emission tomography

BACKGROUND

There is limited knowledge about endothelial dysfunction in patients with primary antiphospholipid syndrome (PAPS). The purpose of this study was to evaluate endothelial function in patients with PAPS assessed by positron emission tomography.

METHODS AND RESULTS

A 3-phase protocol--rest, cold pressor test (CPT), and adenosine positron emission tomography with nitrogen 13 ammonia--was used in 18 patients with PAPS and 18 healthy volunteers (HVs). Myocardial blood flow (MBF) was measured in each phase, with calculation of the endothelial-dependent vasodilation index, the increase in the MBF in response to CPT, and the myocardial flow reserve. An important trend was found in the myocardial flow reserve (2.76 +/- 1.04 in PAPS group vs 3.27 +/- 0.72 in HV group, P > .05), in the endothelial-dependent vasodilation index (1.19 +/- 0.31 in PAPS group vs 1.55 +/- 0.37 in HV group, P < .05), and in the percent change in the MBF in response to CPT (from rest) (19% +/- 31% in PAPS group vs 55% +/- 37% in HV group, P < .05).

CONCLUSION

The CPT results obtained in this study showed that the PAPS patients studied have endothelial dysfunction.

Role of anti-β2 glycoprotein I antibodies in antiphospholipid syndromeglycoprotein I antibodies in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by the presence of recurrent venous/ arterial thrombosis and fetal losses associated with a family of auto-antibodies directed against phospholipid (PL)-binding proteins. Among them, beta2 glycoprotein I (beta2GPI) is the most important. As a plasma cationic protein, beta2GPI binds to anionic PLs involved in several fluid-phase coagulation steps, and more importantly, it can be expressed on the surface of different cell types. Anti-beta2GPI antibodies recognize the molecule expressed on endothelial cells, platelets, monocytes, and trophoblast cells. Once bound, the antibodies trigger in vitro cell signaling that modulates biological responses potentially responsible for pathogenic mechanisms. Experimental animal models have supported the in vivo pathogenic role of anti-beta2GPI antibodies in both thrombosis and fetal loss models.

Antibodies to β2-glycoprotein I and annexin V in women with early and late idiopathic recurrent spontaneous abortions

Anti-phospholipid antibodies (APA) are heterogeneous group of autoantibodies that target phospholipid or phospholipid-binding proteins. APAs were previously shown to induce several thrombotic states, including idiopathic recurrent spontaneous abortion (RSA). Unlike the contribution of the classical lupus anticoagulant (LAC) and anticardiolipin antibodies (ACA), the contribution of anti-beta2 glycoprotein 1 (beta2GPI) and anti-annexin V antibodies to RSA risk remain poorly understood. We assessed anti-beta2GPI and anti-annexin V IgM and IgG antibodies as RSA risk factors for RSA in 172 Tunisian women with >3 consecutive idiopathic pregnancy losses, together with 173 matched control women. The prevalence of anti-beta2GPI IgG (P=0.41, OR=1.64) and IgM (P=0.50, OR=1.70) were comparable between cases and controls. Higher anti-annexin V IgG (P=0.02, OR=5.28), but not IgM (P=0.25, OR=1.78), levels were seen in cases. Regression analysis showed that anti-beta2GPI IgM (OR=8.90; 95% CI=1.23-64.63) was associated with early RSA, while anti-annexin V IgG (OR=9.35, 95% CI=1.44-60.86) was associated with late RSA. For combined early + late RSA, the only variable selected was BMI (OR=0.93; 95% CI=0.87-0.99), and neither anti-annexin V nor anti-beta2GPI IgM and IgG were associated with early + late RSA. Anti-annexin V and anti-beta2GPI appear to be independent risk markers of RSA.

A case-control study on the association of idiopathic recurrent pregnancy loss with autoantibodies against β2-glycoprotein I and annexin V

Whereas antiphospholipid antibodies (aPL) are associated with thrombotic events and recurrent spontaneous abortion (RSA), the contribution of anti-β2 glycoprotein 1 (β2GP1) and anti-annexin V antibodies as risk factors for RSA remain poorly understood. We investigated anti-β2-GPI and anti-annexin V IgM and IgG antibodies as potential risk factors for RSA in 200 women with more than three consecutive idiopathic RSA, and 200 age-matched, healthy, parous women. Pearson’s chi squared test analysis showed that while anti-β2-GPI IgG (P= 0.416) and IgM (P= 0.72) were comparable between patients and controls, elevated anti-annexin V IgG (P= 0.006), but not IgM (P= 0.084), was more pronounced in patients. Higher frequencies of elevated IgG-only (P= 0.005), but not IgM-only (P= 1.000; OR = 6.66), anti-annexin V antibodies were noted among patients. Multinomial regression analysis showed that body-mass index (overweight and obesity;P= 0.008), education status (P< 0.001) and anti-β2-GPI IgM (P= 0.033), but not IgG (P= 0.723), were associated with early abortion, while anti-β2-GPI IgG (P= 0.030) and anti-annexin V IgG (P= 0.004) were associated with late RSA. For combined early-late RSA, the only variable selected was education status (P< 0.001), and neither anti-annexin V nor anti-β2-GPI IgM and IgG was associated with early-late RSA. Accordingly, anti-annexin V and anti-β2-GPI should be regarded as independent risk markers of RSA.

Endothelial function is impaired in patients with primary antiphospholipid syndrome

INTRODUCTION

The aim of this study was to evaluate endothelial function in patients with primary antiphospholipid syndrome (PAPS).

PATIENTS AND METHODS

Flow mediated (FMD) and glyceryl trinitrate (GTN) induced dilation of the right brachial artery were studied in 25 patients with PAPS and 25 controls matched by age, sex and conventional risk factors for atherosclerosis. Fibrinogen, D-dimer, adhesion molecules, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) antigens and activities were measured.

RESULTS

Mean (SD) FMD was significantly lower in PAPS than in controls (8+/-5% vs. 15+/-6%, P<0.001); GTN-induced dilation did not differ between the groups. There was a correlation between the baseline diameter of the brachial artery and duration of the disease (-0.56, P<0.05) and between GTN induced dilation and duration of the disease (0.51, P<0.05). Concentrations of vascular cell adhesion molecule-1 (P<0.001), intracellular adhesion molecule-1 (P<0.001) and fibrinogen (P<0.05) were higher in patients than in controls but no differences were observed for D-dimer, t-PA and PAI-1 antigens and activities. There was correlation between concentration of vascular cell adhesion molecule-1 and FMD (-0.35, P<0.05) and between intracellular adhesion molecule-1 and FMD (-0.41, P<0.05).

CONCLUSIONS

This study shows that endothelial function is impaired in patients with primary APS, possibly contributing to accelerated atherosclerosis and thromboembolic complications in these patients.