Clinical relevance of nitrated beta 2-glycoprotein I in antiphospholipid syndrome: Implications for thrombosis risk.

Β2-Glycoprotein I (ß2GPI) is an important anti-thrombotic protein and is the major auto-antigen in the antiphospholipid syndrome (APS). The clinical relevance of nitrosative stress in post translational modification of ß2GPI was examined.The effects of nitrated (n)ß2GPI on its anti-thrombotic properties and its plasma levels in primary and secondary APS were determined with appropriate clinical control groups. ß2-glycoprotein I was nitrated at tyrosines 218, 275 and 309. ß2-glycoprotein I binds to lipid peroxidation modified products through Domains IV and V. Nitrated ß2GPI loses this binding (p < 0.05) and had diminished activity in inhibiting platelet adhesion to vWF under high shear flow (p < 0.01). Levels of nß2GPI were increased in patients with primary APS compared to patients with either secondary APS (p < 0.05), autoimmune disease without APS (p < 0.05) or non-autoimmune patients with arterial thrombosis (p < 0.01) and healthy individuals (p < 0.05).In conclusion tyrosine nitration of plasma ß2GPI is demonstrated and has important implications with regards to the pathophysiology of platelet mediated thrombosis in APS. Elevated plasma levels of nß2GPI in primary APS may be a risk factor for thrombosis warranting further investigation.

Free Thiol ß2-GPI (ß-2-Glycoprotein-I) Provides a Link Between Inflammation and Oxidative Stress in Atherosclerotic Coronary Artery Disease.

OBJECTIVE: Atherosclerotic coronary artery disease is well recognised as an inflammatory disorder that is also influenced by oxidative stress. ß2-GPI (ß-2-glycoprotein-I) is a circulating plasma protein that undergoes post-translational modification and exists in free thiol as well as oxidized forms. The aim of this study was to assess the association between these 2 post-translational redox forms of ß2-GPI and atherosclerotic coronary artery disease. Approach and Results: Stable patients presenting for elective coronary angiography or CT coronary angiography were prospectively recruited. A separate group of patients after reperfused ST-segment-elevation myocardial infarction formed an acute coronary syndrome subgroup. All patients had collection of fasting serum and plasma for quantification of total and free thiol ß2-GPI. Coronary artery disease extent was quantified by the Syntax and Gensini scores. A total of 552 patients with stable disease and 44 with acute coronary syndrome were recruited. While total ß2-GPI was not associated with stable coronary artery disease, a higher free thiol ß2-GPI was associated with its presence and extent. This finding remained significant after correcting for confounding variables, and free thiol ß2-GPI was a better predictor of stable coronary artery disease than hs-CRP (high-sensitivity C-reactive protein). Paradoxically, there were lower levels of free thiol ß2-GPI after ST-segment-elevation myocardial infarction. CONCLUSIONS: Free thiol ß2-GPI is a predictor of coronary artery disease presence and extent in stable patients. Free thiol ß2-GPI was a better predictor than high-sensitivity C-reactive protein.

Nine-test panel has superior sensitivity to detect antiphospholipid antibody syndrome in patients with or without SLE.

Anti-phospholipid antibodies (aPL) and lupus anticoagulant (LAC) represent diagnostic criteria for systemic lupus erythematosus (SLE) and underlie anti-phospholipid syndrome (APS) in patients with and without SLE. 526 healthy controls and 1633 SLE and 1835 primary APS (PAPS) patients were evaluated. LAC was assessed by hexagonal phase phospholipid neutralization assay (HPPNA), diluted Russell viper venom test (dRVVT), and platelet neutralization procedure (PNP). ß2-glycoprotein-I and cardiolipin IgG, IgM, and IgA antibodies (aCL-IgG, aCL-IgM, aCL-IgA) were measured. 222/1633 SLE patients had APS based on the nine-test panel, which afforded the highest sensitivity (74%) and negative predictive value (90%) but lowest specificity (52%). HPPNA was the most sensitive individual test at 52%. The nine-test panel yielded the greatest sensitivity for aPL detection (70%) relative to HPPNA, the most sensitive individual test (36%) in PAPS. Superior sensitivity of a nine-test aPL panel has major implications for preventing potentially fatal thrombotic events in SLE and PAPS.

Development of a certified reference material for anti-ß2-glycoprotein I IgG - commutability studies.

Objectives: In this paper, we describe the steps followed for the development of a certified reference material for immunoglobulin G antibodies against ß2-glycoprotein I (also known as apolipoprotein H). These steps include processing of the material, commutability, the impact of dilution, the appropriate reconstitution conditions, homogeneity and stability during transport and storage. Methods: We analysed 69 clinical samples from patients suffering from antiphospholipid syndrome with several commercial enzyme-linked immunosorbent assays (ELISA) purchased from in vitro diagnostic manufacturers. Results: Analysis of the results indicated that the candidate reference material can be safely freeze-dried, and that the user should carefully follow the reconstitution instructions as small changes in e.g. temperature may have unwanted effects. The statistical analysis of the commutability studies indicated that the analytical response of the reference material upon dilution is similar to that of clinical samples, and that correlation between results may differ from assay to assay. Finally yet importantly, the presented and developed candidate reference material is commutable for most assays tested, homogeneous and stable. Conclusions: Immunoglobulin G antibodies against ß2-glycoprotein I are associated with a higher risk of thrombosis and pregnancy complications. Their measurement is essential for the diagnosis and monitoring of antiphospholipid syndrome. These antibodies are detected by specific immunoassays, routinely used in clinical diagnostics, but various of these methods show enormous variability, in part due to the lack of a reference material.

New insight into antiphospholipid syndrome: antibodies to ß2glycoprotein I-domain 5 fail to induce thrombi in rats.

Clinical studies have reported different diagnostic/predictive values of antibodies to domain 1 or 4/5 of ß2glycoproteinI in terms of risk of thrombosis and pregnancy complications in patients with antiphospholipid syndrome. To obtain direct evidence for the pathogenic role of anti-domain 1 or anti-domain 4/5 antibodies, we analyzed the in vivo pro-coagulant effect of two groups of 5 sera IgG each reacting selectively with domain 1 or domain 5 in lipopolysaccharide (LPS)-treated rats. Antibody-induced thrombus formation in mesenteric vessels was followed by intravital microscopy, and vascular deposition of ß2glycoproteinI, human IgG and C3 was analyzed by immunofluorescence. Five serum IgG with undetectable anti-ß2glycoproteinI antibodies served as controls. All the anti-domain 1-positive IgG exhibited potent pro-coagulant activity while the anti-domain 5-positive and the negative control IgG failed to promote blood clot and vessel occlusion. A stronger granular deposit of IgG/C3 was found on the mesenteric endothelium of rats treated with anti-domain 1 antibodies, as opposed to a mild linear IgG staining and absence of C3 observed in rats receiving anti-domain 5 antibodies. Purified anti-domain 5 IgG, unlike anti-domain 1 IgG, did not recognize cardiolipin-bound ß2glycoproteinI while being able to interact with fluid-phase ß2glycoproteinI. These findings may explain the failure of anti-domain 5 antibodies to exhibit a thrombogenic effect in vivo, and the interaction of these antibodies with circulating ß2glycoproteinI suggests their potential competitive role with the pro-coagulant activity of anti-domain 1 antibodies. These data aim at better defining "really at risk" patients for more appropriate treatments to avoid recurrences and disability.

Antiphospholipid antibodies in patients with lupus nephritis: clinical correlations and associations with long-term outcomes.

Whether the presence or absence of antiphospholipid antibodies (aPL) in patients with lupus nephritis (LN) is associated with differences in clinical outcomes remains unclear. We reviewed LN patients at a single centre during 2000-2017, and compared the clinical features and long-term outcomes between patients who were seropositive or seronegative for aPL. aPL was detected in 53/149 (35.6%) patients with biopsy-proven LN, and anticardiolipin IgM, anticardiolipin IgG, anti-ß2 glycoprotein I and lupus anticoagulant was detected in 18.8%, 18.1%, 10.7% and 8.1%, respectively. Follow-up was 155.8 ± 61.0 months, and was similar between aPL-seropositive and -seronegative patients. aPL seropositivity persisted in 94.3% of patients during remission. aPL-seropositive patients showed inferior patient survival (91% and 85% at 10 and 15 years, respectively, compared to 99% and 95% in aPL-seronegative patients; p = 0.043). Nine (6.0%) patients died during follow-up, including six aPL-seropositive (four thrombotic events and two bleeding complications related to anticoagulation) and three aPL-seronegative patients. aPL seropositivity was associated with more rapid decline in estimated glomerular filtration rate (-1.44 mL/min/year compared to -0.38 mL/min/year in aPL-seronegative patients; p = 0.027) and inferior long-term renal survival (82% and 74% at 10 and 15 years, respectively, compared to 91% and 87% in aPL-seronegative patients; p = 0.034). aPL-seropositive patients also had a higher incidence of thrombotic events and miscarriage (32.1% and 13.2%, respectively, compared to 16.7% and 2.1% in the aPL-seronegative group; p = 0.030 and 0.006). We concluded that aPL seropositivity was associated with inferior long-term patient and renal survival and more frequent thrombotic events and miscarriage in LN patients.

Elevation of serum oxLDL/ß2-GPI complexes was correlated with diabetic microvascular complications in Type 2 diabetes mellitus patients.

BACKGROUND: High levels of oxLDL/ß2-GPI complexes might be a consequence of LDL atherogenic modification mediated by oxidative stress. We aimed to determine whether the levels of serum oxLDL/ß2-GPI complexes were correlated with diabetic microvascular complications in type 2 diabetes mellitus (T2DM) patients. METHODS: Levels of oxLDL/ß2-GPI complexes, oxLDL, routine lipid/lipoprotein parameters were measured in 100 healthy controls, 128 T2DM patients without any microvascular complications, and 172 T2DM patients with microvascular complications. Spearman's correlation, multivariable linear regression logistic regression analysis, and receiver operating characteristic (ROC) curve were performed. RESULTS: Levels of serum oxLDL/ß2-GPI complexes and oxLDL were significantly higher in T2DM patients with microvascular complications (oxLDL/ß2-GPI complexes: 1.10 ± 0.18 U/mL; oxLDL: 48.12 ± 7.24 mmol/L) than those in T2DM patients without microvascular complications (oxLDL/ß2-GPI complexes: 0.98 ± 0.16 U/mL; oxLDL: 41.45 ± 6.81 mmol/L) and controls (oxLDL/ß2-GPI complexes: 0.79 ± 0.15 U/mL; oxLDL: 27.85 ± 5.32 mmol/L). Variables that remained significantly associated with oxLDL/ß2-GPI complexes were oxLDL (ß = 0.568, P < 0.001), TC (ß = 0.312, P = 0.013) and microvascular complications (ß = 0.205, P = 0.027), which accounted for 58.3% of the variation of the level of oxLDL/ß2-GPI complexes in T2DM patients (R2 = 0.583). Logistic regression analysis demonstrated that elevation of oxLDL/ß2-GPI complexes (OR = 3.14, 95% CI: 1.04-9.46, P = 0.042) and oxLDL levels (OR = 3.02, 95% CI: 1.16-7.83, P = 0.023) were independently associated with occurrence of microvascular complications. Cutoff value of oxLDL/ß2-GPI for the presence of microvascular complications was 1.05 U/mL, and AUC area of ROC curve was 0.783 (95%CI: 0.713-0.853), yielding a sensitivity of 86.8% and specificity of 64.9%. CONCLUSIONS: Elevation of serum oxLDL/ß2-GPI complexes was associated with microvascular complications in T2DM patients.

ß2-Glycoprotein I/IgA Immune Complexes: A Marker to Predict Thrombosis After Renal Transplantation in Patients With Antiphospholipid Antibodies.

BACKGROUND: Antiphospholipid syndrome is characterized by recurrent thrombosis and gestational morbidity in patients with antiphospholipid autoantibodies (aPLs). Predictive value of the presence of aPLs is low, and new markers are necessary to identify aPL carriers at higher risk and take preventive measures on them. The presence of circulating immune complexes of IgA bound to ß2-glycoprotein I (B2A-CIC) has been associated with occurrence of acute thrombotic events. In this work we study its possible predictive value for the appearance of acute thrombotic events in patients who are going to undergo transplant surgery, a well-known trigger of acute thrombotic events in aPL carriers. METHODS: We performed a follow-up study based on the Magnum 12+12 Cohort of patients who received a kidney transplant (n=1339). Three groups were established: group 1 patients who were positive for IgA anti-ß2-glycoprotein I (aB2GP1) and B2A-CIC (n=125); group 2 patients who were positive only for IgA aB2GP1 (n=240); and control group, patients who were negative for IgA aB2GP1 (n=974). Levels of autoantibodies and B2A-CIC were quantified immediately before the transplant surgery and patients were followed up for 6 months. RESULTS: In group 1, 46.4% of patients experienced any type of thrombosis versus 10.4% in group 2 (P<0.001) and 8.6% in the control group (P<0.001). The incidence of graft thrombosis in group 1 (31.2%) was significantly higher than that observed in group 2 (3.3%, P<0.001) and the control group (2.6%, P<0.001). In a multivariate analysis, the presence of B2A-CIC was an independent variable to experience any type of posttransplant thrombosis (hazard ratio, 6.72; 95% confidence interval, 4.81-9.37) and, prominently, for graft thrombosis (hazard ratio, 14.75; 95% confidence interval, 9.11-23.89). No significant differences were found between B2A-CIC-negative and control group patients. CONCLUSIONS: The presence of B2A-CIC is a predictor of acute thrombotic events. Patients who were positive for IgA aB2GP1 only are at risk of experiencing thrombosis if they are B2A-CIC positive. If they are B2A-CIC-negative patients, they have the same risk as the control group. Treatments to prevent acute thrombotic events should focus on B2A-CIC-positive patients.

Serum oxLDL-ß2GPI complex reflects metabolic syndrome and inflammation in adipose tissue in obese.

BACKGROUND/OBJECTIVES: OxLDL-ß2GPI complex has been suggested to have a role in the development of atherosclerosis and other inflammatory diseases. The aim of this study was to investigate the possible association of circulating oxLDL-ß2GPI with obesity-induced inflammatory state of adipose tissue and related comorbidities as metabolic syndrome development. SUBJECTS/METHODS: Two cohorts of subjects were examined in the study. Cohort I: 36 women with wide range of body mass index (17-48 kg m-2) and metabolic status (with or without metabolic syndrome (MS); cohort II: 20 obese women undergoing a dietary intervention (DI) consisting of 1-month very-low-calorie diet, and 5 months of weight-stabilization period. Serum levels of oxLDL-ß2GPI were measured by enzyme-linked immunosorbent assay. Insulin sensitivity was evaluated by hyperinsulinemic-euglycemic clamp and homeostasis model assessment of insulin resistance. mRNA expression of macrophage markers was determined in both subcutaneous (SAT) and visceral (VAT) adipose tissue in cohort I and in SAT in cohort II. RESULTS: Serum oxLDL-ß2GPI levels were increased in obese subjects with MS compared to lean or obese without MS (obese with MS: 26.6±5.0 vs lean: 15.17±1.97, P<0.001; vs obese without MS: 16.36±2.89, P<0.05). Serum oxLDL-ß2GPI correlated with MS indices (glucose, high-density lipoprotein, triglyceride and ureic acid) and with mRNA expression of macrophage markers in VAT. Weight-reducing DI decreased serum oxLDL-ß2GPI levels together with lipid parameters and the mRNA expression of inflammatory markers in SAT. CONCLUSIONS: OxLDL-ß2GPI seems to be an important marker of visceral adipose tissue inflammation and possibly a factor contributing to insulin resistance and metabolic syndrome development in obese patients.

Diminished expression of ß2-GPI is associated with a reduced ability to mitigate complement activation in anti-GPIIb/IIIa-mediated immune thrombocytopenia.

Anti-GPIIb/IIIa-mediated complement activation has been reported to be important in the pathogenesis of immune thrombocytopenia (ITP). However, the role of the complement system and the involved regulatory mechanism remain equivocal. Beta2-glycoprotein I (ß2-GPI), known as the main target for antiphospholipid autoantibodies, has been demonstrated as a complement regulator. Here, we investigated the complement-regulatory role of ß2-GPI in anti-GPIIb/IIIa-mediated ITP. Plasma complement activation and enhanced complement activation capacity (CAC) were found in ITP patients with anti-GPIIb/IIIa antibodies in vivo and in vitro. Diminished plasma levels of ß2-GPI were shown in patients of this group, which was inversely correlated with C5b-9 deposition. C5b-9 generation was inhibited by approximate physiological concentrations of ß2-GPI, in a dose-dependent manner. Inhibition of C3a generation by ß2-GPI and the existence of ß2-GPI/C3 complexes in plasma indicated a regulation on the level of the C3 convertase. Furthermore, ß2-GPI down-regulated the phosphorylation levels of c-Jun N-terminal kinase (JNK) and cleavage of BH3 interacting domain death agonist (Bid) and ultimately harbored platelet lysis. Our findings may provide a novel link between diminished plasma levels of ß2-GPI and enhanced complement activation, indicating ß2-GPI as a potential diagnostic biomarker and therapeutic target in the treatment of anti-GPIIb/IIIa-mediated ITP.

The Clinical Performance of a New Chemiluminescent Immunoassay in Measuring Anti-ß2 Glycoprotein 1 and Anti-Cardiolipin Antibodies.

BACKGROUND Laboratory criterion is needed for the classification of antiphospholipid syndrome (APS), which contain anticardiolipin antibodies (aCL) and anti-ß2-glycoprotein 1 antibodies (aß2GP1). They are commonly identified by enzyme-linked immunosorbent assay (ELISA), but lack standardized kits, resulting in substantial variations in the antibody positivity between different laboratories. The emergence of chemiluminescence automated -BIO-FLASH may improve the situation. MATERIAL AND METHODS We selected 185 patients with APS, systemic lupus erythematosus (SLE), infertility, connective tissue disease (CTD), and other conditions in Peking University Third Hospital. We tested the aCL and aß2GP1 levels by EUROIMMUN ELISA and 105 patients had at least one positive result for aCL and aß2GP1, while the others had negative results. We retested them by chemiluminescence assay (CIA) and analyzed the result and compared the coincidence rate. The IgM levels were retested by AESKU ELISA. Data were analyzed using SPSS. RESULTS Our result suggested that CIA had good performance for IgG isotype of aCL and aß2GP1 in the coincidence rate. The positive coincidence rate of aCL IgM between CIA and EUROIMMUN ELISA was only 41.67%, but two ELISA kits showed good coincidence, CIA and AESKU ELISA had an obviously higher positive rate. CIA and AESKU had a higher coincidence than that of AESKU and EUROIMMUN in aß2GP1-IgM. CONCLUSIONS The new automated CIA BIO-FLASH is suitable for detecting aCL and aß2GP1 antibodies, especially IgG isotype, which may provide an alternative to time-consuming conventional ELISA method.

Elevated Levels of Serum ß2-Glycoprotein I/Oxidized Low-Density Lipoprotein Complexes Are Associated with Cerebral Infarction in Patients with Type 2 Diabetes Mellitus.

BACKGROUND To determine whether the levels of b2-glycoprotein I (b2-GPI)/oxidized low-density lipoprotein (oxLDL) complexes are correlated with cerebral infarction in patients with type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS The levels of ß2-GPI/oxLDL complexes, oxLDL, routine lipid/lipoprotein parameters, oxidative stress molecules, and inflammatory factors were measured in 78 healthy controls, 82 diabetics without cerebral infarction, and 79 diabetics with cerebral infarction. Correlation, multiple linear regression, and logistic regression analyses were performed. RESULTS Serum ß2-GPI/oxLDL complexes and oxLDL levels were significantly elevated in cerebral infarction in patients with T2DM (ß2-GPI/oxLDL: 1.09±0.16 U/mL; oxLDL: 47.83±8.17 mmol/L) compared with T2DM without cerebral infarction (b2-GPI/oxLDL: 0.95±0.13 U/mL; oxLDL: 41.24±7.12 mmol/L) and healthy controls (ß2-GPI/oxLDL: 0.81±0.12 U/mL; oxLDL: 27.97±4.57 mmol/L). The levels of ß2-GPI/oxLDL complex in lacunar infarction (1.16±0.15 U/ml) were significantly higher than atherothrombotic infarction (1.07±0.19 U/ml) and cardioembolic infarction (1.00±0.23 U/ml). In all patients with T2DM, the ß2-GPI/oxLDL levels were positively correlated with total cholesterol (r=0.474, p=0.001) and triglycerides (r=0.431, p=0.003). oxLDL levels were positively correlated with total cholesterol (r=0.445, p=0.002). The logistic regression analysis indicated that elevated b2-GPI/oxLDL and oxLDL levels were independently associated with diabetic cerebral infarction. CONCLUSIONS Elevated levels of serum b2-GPI/oxLDL complexes are associated with cerebral infarction in patients with T2DM, especially in those with lacunar infarction.

[The comparative analysis of immunologic techniques of detection of anti-phospholipid antibodies].

The laboratory diagnostic of anti-phospholipid syndrome consists in detection of anti-phospholipid antibodies using technique of enzyme-linked immunosorbent assay namely in detection of anti-cardiolipin antibodies and antibodies to ß2-glycoprotein. In spite of the fact that serological diagnostic plays a key role in diagnosing anti-phospholipid syndrome application of laboratory tests s complicated by their insufficient standardization. The new approach to detection of anti-phospholipid antibodies became application of immune blotting on the basis of polyvinylidenfluoride membrane. As compared with enzyme-linked immunosorbent assay, the advantage of the mentioned technique is in using hydrophobic solid phase for sorption of antigens. The porous structure of polyvinylidenfluoride membrane orientates hydrophilic areas of phospholipids and by that ensures their more dense distribution imitating bi-lipid layer of membranes of living organism. To specify and compare value of different techniques the comparison was implemented concerning the results of measurement of anti-phospholipid antibodies in enzyme-linked immunosorbent assay test-systems of various manufacturers and reagents kits for immune blotting. The collection was assembled including bio-materials from 47 patients with non-cardioembolic ischemic strokes, 20 patients with recurrent thrombosis of deep veins of lower extremities and 50 patients with obstetrics pathology and also 30 healthy donors. In the given serums aKlaIgG, aKlaIgM, aß2glycoprotein I were measured using enzyme-linked immunosorbent assay technique assisted by test-systems of Euroimmun and Orgentes Diagnostica and the samples with the highest titre using immune blotting technique with reagents manufactured by Medipan. On the basis of measurement of anti-phospholipid antibodies by various enzyme-linked immunosorbent assay test-systems the rate of aß2glycoprotein I amounted to 31% in case of Euroimmun reagents kits for enzyme-linked immunosorbent assay, 78% in case of Orgentec Diagnistica test-systems for enzyme-linked immunosorbent assay, aKlaIgG - 2% and 30%, aKlaIgM - 31% and 54% correspondingly. The measurement of anti-phospholipid antibodies using immune blotting technique on Medipan test-systems in bio-samples with the highest titres detected aß2glycoprotein I in all patients, aKlaIgG in 70% and aKlaIgM in 30% of patients. The convergence between three commercial reagents kits varies from 20% to 88%. The standardization of commercial test-systems still to be achieved. The new technique of immune blotting can be appliedjointly with classic techniques ofserological diagnostic of anti-phospholipid syndrome. The absence of algorithms of diagnostic and standardization of different test-systems for detection of anti-phospholipid antibodies prejudices reliability of serological diagnosis of anti-phospholipid syndrome and therefore existence of anti-phospholipid syndrome as a nosologic unit.

The role of clinically significant antiphospholipid antibodies in systemic lupus erythematosus.

The objective is to investigate the role of clinically significant antiphospholipid antibodies (aPL) in a cohort of systemic lupus erythematosus (SLE) patients. All SLE patients followed for at least 5 years and with available aPL profile at the beginning of the follow-up in our center were studied. Clinically significant aPL were defined as: positive lupus anticoagulant test, anti-cardiolipin and/or anti- ß2Glycoprotein I IgG/IgM >99th percentile on two or more occasions at least 12 weeks apart. Patients with and without clinically significant aPL were compared by univariate (Chi square or Fisher's exact test for categorical variables and Student's t or Mann-Whitney test for continuous variables) and multivariate analysis (logistic regression analysis). P values <0.05 were considered significant. Among 317 SLE patients studied, 117 (37%) had a clinically significant aPL profile at baseline. Such patients showed at univariate analysis an increased prevalence of deep venous thrombosis, pulmonary embolism, cardiac valvular disease, cognitive dysfunction and antiphospholipid syndrome (APS), but a reduced prevalence of acute cutaneous lupus and anti-extractable nuclear antigens (ENA) when compared with patients without clinically significant aPL. Multivariate analysis confirmed the association between clinically significant aPL and reduced risk of acute cutaneous lupus [p=0.003, odds ratio (OR) 0.43] and ENA positivity (p<0.001, OR 0.37), with increased risk of cardiac valvular disease (p=0.024, OR 3.1) and APS (p<0.0001, OR 51.12). Triple positivity was the most frequent profile and was significantly associated to APS (p<0.0001, OR 28.43). Our study showed that one third of SLE patients had clinically significant aPL, and that this is associated with an increased risk, especially for triple positive, of APS, and to a different clinical and serological pattern of disease even in the absence of APS.

[OxLDL/ß2-glycoprotein I complex as a pro-atherogenic autoantigen. Is atherosclerosis an autoimmune disease?] / Komplex oxLDL/ß2-glykoprotein I jako proaterogenní autoantigen. Je ateroskleróza autoimunitní onemocnení?

Oxidation of atherogenic low-density lipoproteins (LDL) plays a key role in the pathogenesis of atherosclerosis. Oxidation stress and inflammation are closely interrelated and they can potentiate one another. In the subendothelial space of the arterial intima, monocytes/macrophages become activated and phagocyte oxidized LDL (oxLDL) via scavenger receptors. It has been demonstrated that oxLDL forms complex with plasma ß2-glycoprotein I (ß2GPI) and becomes autoantigenic triggering synthesis of specific antiphosholipid antibodies. It has been documented that oxLDL/ß2GPI in immune complex with IgG autoantibody is internalized by macrophages through the Fcγ receptor. Increased levels of oxLDL/ß2GPI were first observed in patients with systemic lupus erythematodes (SLE) and antiphospholipid syndrome (APS), further in individuals with coronary heart disease (CHD) and type 2 diabetes mellitus (DM2T). In a prospective study, initial plasma concentrations of oxLDL/ß2GPI correlated with the number and severity of cardiovascular events in patients with chronic CHD over a 2-year period.Key words: atherosclerosis - ß2-glycoprotein I - inflammation - oxidative stress - oxLDL.

Screening and identification of potential predictive biomarkers for Down's syndrome from second trimester maternal serum.

OBJECTIVE: In this study, we aimed to search for noninvasive predictive biomarkers for prenatal diagnosis of Down's syndrome (DS). METHODS: Maternal serum samples from five DS-affected pregnant women and five DS-unaffected women were analyzed by 2D gel electrophoresis and MALDI-TOF mass spectrometry to screen for potential predictive biomarkers of DS. Then, differential levels of dGTPase, ß2-glycoprotein I (ß2-GPI), complement factor H-related protein 1 precursor (CFHR1) and kininogen 1 isoform 2 were further verified by western blotting tests in another independent group. RESULTS: Statistical analysis results revealed 29 protein spots whose levels differed significantly in the DS-affected pregnancies group. Of these, the eight most differentially expressed in DP were identified successfully. Among these, levels of dGTPase, CFHR1 and kininogen 1 were elevated significantly, whereas ß2-GPI was reduced in DP. DISCUSSION: These preliminarily verified proteins might serve as potential predictive biomarkers for DS-affected pregnancies.

Elevated expression of platelet-derived chemokines in patients with antiphospholipid syndrome.

OBJECTIVE: Platelet factor 4 tetramers (CXCL4 chemokine) form complexes with ß2glycoprotein I (ß2GPI), recognized by anti-ß2GPI antibodies leading to platelet activation in antiphospholipid syndrome (APS), either primary (PAPS) or secondary (SAPS). Increased plasma levels of CXCL4 may favor this process; therefore we measured plasma levels of CXCL4, a CXCL4 variant (CXCL4L1) and as controls, platelet-derived chemokines CXCL7 (NAP-2) and CCL5 (RANTES), in APS, and disease controls such as patients with systemic lupus erythematosus (SLE) coronary artery disease (CAD) and healthy donors (HDs). METHODS: Plasma samples and platelets were isolated from patients with APS (n = 87), SLE (n = 29), CAD (n = 14) and 54 HDs. Plasma levels of CXCL4, CXCL4L1, CXCL7 and CCL5 as well as intracellular platelet CXCL4 and CXCL4L1 were measured using ELISA. Platelet CXCL4 and CXCL4L1 RNA levels were determined by RT-PCR. RESULTS: CXCL4, CXCL7 (NAP-2) and CCL5 (RANTES) plasma levels were significantly higher in patients with APS compared to both control groups (SLE, CAD) and HDs. CXCL4L1 plasma levels were also significantly higher in APS than in SLE and HDs, but lower from that of CAD patients. Statistically significant concordance was detected between CXCL4 and CXCL7 (p < 0.0001) or CCL5 (p < 0.0001) plasma levels in patients with APS, either PAPS or SAPS. CXCL4L1 plasma levels were inversely correlated with CXCL4 (P = 0.0027), CXCL7 (p = 0.012) and CCL5 (p = 0.023) in PAPS and positively with CXCL4 (p = 0.0191), CCL5 (p < 0.0001) and CXCL7 (P < 0.0001), in SAPS. Levels of CXCL4, CXCL4L1, CXCL7 and CCL5 were divided in "high" (exceeding a level defined as the mean of HDs and 3 SD) and "low" (below this level); The "CXCL4L1 high" group was characterized by increased IgG aCL, (p = 0.0215), double antibody positivity (either aCL or anti-ß2GPI plus LA), (p = 0.0277), triple antibody positivity (aCL plus anti-ß2GPI plus LA), (p = 0.0073) and thrombocytopenia (p = 0.0061), as well as with at least 1 thrombotic event or the last 5 years (p = 0.0001), or more than 3 thrombotic events ever (p = 0.0151). CONCLUSIONS: Chemokines associated with platelet activation and immune cell chemotaxis were found to be elevated in APS patients' plasma and may contribute to the pathogenesis of the syndrome. High CXCL4L1 plasma levels are associated with the clinical expression of APS and should be prospectively evaluated as a biomarker.

Examining the prevalence of non-criteria anti-phospholipid antibodies in patients with anti-phospholipid syndrome: a systematic review.

OBJECTIVE: To systematically review and establish the prevalence of antibody positivity in assays not currently included in the APS classification criteria to detect antibodies directed against other phospholipids (PLs), PL binding proteins, coagulation factors and a mechanistic test for resistance of Annexin A5 (AnxA5) anticoagulant activity in APS and control populations. METHODS: We searched PubMed and EMBASE using the key words APS, antiphospholipid antibodies, non-criteria, new assays, IgA anticardiolipin antibodies, lupus anticoagulant, anti-Domain I, IgA anti-ß2-glycoprotein I antibodies, antiphosphatidylserine, anti-phosphatidylethanolamine, anti-phosphatidic acid, antiprothrombin, antiphosphatidylserine-prothtombin, anti-vimentin/cardiolipin complex and Annexin A5 resistance. Studies that met inclusion criteria to describe prevalence of non-criteria aPLs in APS patients (n > 10), disease and healthy control subjects were systematically examined. RESULTS: We selected 16 retrospective studies of 1404 APS patients, 1839 disease control and 797 healthy controls. The highest prevalence of non-criteria aPLs in the largest number of patients with APS was found in IgA anti-ß2GPI studies (129/229, 56.3%), AnxA5R (87/163, 53.4%) and IgG anti-Domain I (241/548, 44.0%). CONCLUSION: Our finding of a significantly high prevalence of all non-criteria aPLs studied in patients with APS compared with controls was tempered by wide variation in sample size, retrospective collection, assay methodology and different determination of positivity. Therefore, prospective studies of sufficient size and appropriate methodology are required to evaluate the significance of these assays and their utility in the management of patients with APS.

Plasma apolipoprotein H limits HCV replication and associates with response to NS3 protease inhibitors-based therapy.

BACKGROUND & AIMS: Chronic infection with HCV remains a public health problem with approximately 150 million people infected worldwide. HCV intersects with lipid metabolism for replication and entry; and plasma concentrations of apolipoproteins have been identified as predictors for response to therapy. Herein, we conducted a screen of plasma proteins, including all apolipoproteins, to identify correlates of response to pegylated-interferon/ribavirin (PR) and HCV non-structural protein 3 (NS3) inhibitors (i.e., telaprevir/boceprevir) therapy in treatment-experienced cirrhotic patients from the ANRS CUPIC cohort. METHODS: We analysed 220 baseline plasma protein concentrations in 189 patients using Luminex technology and analyzed results. RESULTS: We identified baseline levels of apolipoprotein H (apoH) as a surrogate marker for sustained virological response (SVR). Notably, increased plasma concentration of apoH, used in combination with known clinical parameters, established a robust model with improved classification of patients as likely to achieve SVR (AUC = 0.77, Se = 66%, Sp = 72%, NRI = 39%). Moreover, we provide mechanistic information that indicates a previously unidentified role for apoH during viral entry. Using a human liver slices HCV infection model, we demonstrate that apoH limits replication. CONCLUSION: These data support testing of new biomarker strategies for the management of cirrhotic HCV patients and expand our understanding of how apoH may intersect with HCV infection.

Thrombotic microangiopathy and poor renal outcome in lupus patients with or without antiphospholipid syndrome.

OBJECTIVES: To assess the presence of acute thrombotic microangiopathy (aTMA) and chronic vascular lesions (cTMA) in lupus nephropathy, and to evaluate their association with extrarrenal lupus features, aPL positivity, antiphospholipid syndrome (APS) and renal survival. METHODS: We studied lupus patients with renal biopsy, ≥1 year of post-biopsy follow-up and at least two aCL (IgG-IgM), anti-ß2GP-I (IgG-IgM) and/or lupus anticoagulant (LAC) determinations. A blinded nephropathologist evaluated all biopsies. We retrospectively collected clinical, serological, treatment and renal survival data. We plotted survival curves and used Cox regression analysis. RESULTS: A total of 90 biopsies were included with a median disease duration 5.9 years and median follow-up 2.4 years. Eleven patients (12.2%) had cTMA and 3 (3%) aTMA. There was no difference in age, lupus duration, hypertension, drugs, APS, non-renal lupus features, low C3 or C4 aCL IgG, anti-ß2GP1-IgG or IgM and LAC between cTMA and non-cTMA groups. The cTMA group had aCL-IgM less frequently (27% vs. 66%, p=0.02), more class IV nephropathy (100% vs. 40%, p=0.01), higher activity index scores (7.5 vs. 2, p=0.03) and a tendency to need chronic dialysis (54.5% vs. 24% p=0.06). At four years of follow-up, 28% of the cTMA group and 62% of the non-cTMA group were free of dialysis (log rank p=0.03). cTMA was associated with chronic dialysis (RR 2.9, CI 95% 1.1-8.1, p=0.03). CONCLUSIONS: cTMA conferred a poor renal outcome. We found a low frequency of TMA that was not associated with with APL positivity or APS, suggesting that other factors hitherto not studied are involved in its pathogenesis.