The meaning of non-criteria clinical manifestations in a real-life primary antiphospholipid syndrome cohort.

OBJECTIVES: We aimed to evaluate the prevalence of non-criteria clinical features in patients with primary antiphospholipid syndrome (APS), and to assess their relationship to thrombosis and damage. METHODS: We retrospectively included 177 primary APS patients, and/or patients who only achieved the serological Sydney criteria but had thrombocytopenia and/or haemolytic anaemia. We registered demographics, serology, treatment, thrombotic/obstetric manifestations and non-criteria clinical manifestations (cutaneous, haematologic, renal, heart valve disease, and neurological). We scored the DIAPS and a modified SLICC index. We used logistic regression and reported OR with 95% CI. RESULTS: 78% were women with a median follow-up of 6.7 years. Thrombosis was found in 74% of patients, 29.3% had obstetric features, and 64% had non-criteria clinical manifestations. The frequency of the non-criteria clinical manifestation was: haematologic 40.1%, cutaneous 20.9%, neurologic 18%, cardiac 5% and renal 4.5%. Non-criteria features were associated with LA (OR 2.3, 95% 1.03-5.1) and prednisone use (OR 8.2, 95% CI 1.7-39.3). A DIAPS score ≥1 was associated with thrombosis (OR 53.1, 95% CI 17.8-15.2), prednisone use (OR 0.27, CI 95% 0.09-0.83) and neurological involvement (OR 6.4, 95% CI 1.05-39.8); whereas a modified SLICC ≥ 1 with thrombosis (OR 10.2; IC 95% 4.43-26.1), neurological involvement (OR 6.4, 95%CI 1.05-39.8), obstetric features (OR 0.32 CI 95% 0.12-0,81) and cutaneous features (OR 5.3, CI 95% 1.4-19), especially livedo reticularis (OR 5.45; IC 95% 1.49-19.8). CONCLUSIONS: Non-criteria clinical manifestations are common and associated with LA. Among them, neurologic involvement and the presence of livedo were associated with damage accrual.

Endothelial progenitor dysfunction associates with a type I interferon signature in primary antiphospholipid syndrome.

OBJECTIVES: Patients with antiphospholipid syndrome (APS) are at risk for subclinical endothelial injury, as well as accelerated atherosclerosis. In the related disease systemic lupus erythematosus, there is a well-established defect in circulating endothelial progenitors, which leads to an accrual of endothelial damage over time. This defect has been at least partially attributed to exaggerated expression of type I interferons (IFNs). We sought to determine whether these pathways are important in APS. METHODS: We studied 68 patients with primary APS. Endothelial progenitors were assessed by flow cytometry and functional assay. Type I IFN activity was determined by a well-accepted bioassay, while peripheral blood mononuclear cells were scored for expression of IFN-responsive genes. RESULTS: Endothelial progenitors from patients with APS demonstrated a marked defect in the ability to differentiate into endothelial cells, a phenotype which could be mimicked by treating control progenitors with APS sera. Elevated type I IFN activity was detected in the circulation of patients with APS (a finding that was then replicated in an independent cohort). While IgG depletion from APS sera did not rescue endothelial progenitor function, the dysfunction was successfully reversed by a type I IFN receptor-neutralising antibody. CONCLUSIONS: We describe, for the first time to our knowledge, an IFN signature in primary APS and show that this promotes impaired endothelial progenitor function. This work opens the door to novel approaches that may mitigate vascular damage in APS, such as anti-IFN drugs.

Perioperative management of patients with antiphospholipid syndrome: a single-center experience.

The objective was to describe the management and risk factors for complications of antiphospholipid syndrome (APS) patients who underwent a surgical procedure in a single center. We reviewed medical records of all patients with primary or secondary APS who underwent an elective surgery during a 6-year period. Demographical data, management of anticoagulation and complications were recorded. We identified 43 patients, mean age 37.9 ± 8.9 years, who underwent a total of 48 elective surgeries. All patients had history of at least one thrombotic event and were under vitamin K antagonists. Before surgery, all patients received bridging therapy with intravenous infusion of heparin or low molecular weight heparin (LMWH). Among the LMWH group, 36 had a full anticoagulation regimen and nine prophylactic doses. In 62% of the surgeries, we identified an optimal management of periprocedural anticoagulation according to guidelines. Overall six patients had severe bleeding and three thrombotic complications (full anticoagulation regimen n = 2 and prophylactic dose group n = 1). Patients with optimal management of anticoagulation experienced less thrombotic and hemorrhagic complications (7 vs. 33%; OR 0.14, 95% CI 0.02-0.81; p = 0.040) and patients with INR ≤1.5 at surgery had fewer episodes of major bleeding (6 vs. 29%; OR 0.19, 95% CI 0.02-0.98; p = 0.050). All three thrombotic events occurred in patients with INR ≤1.5. Proper management of anticoagulation based on guidelines is associated with less complications in patients with APS. Notwithstanding the proper use of bridging therapy, some patients may develop thrombotic complications.

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.

The role of ß2-glycoprotein I (ß2GPI) carbohydrate chains in the reactivity of anti-ß2GPI antibodies from patients with primary antiphospholipid syndrome and in the activation and differentiation of U937 cells.

Several studies have shown that conformational changes of ß(2)-glycoprotein I (ß(2)GPI) when bound to negatively charged components expose cryptic epitopes and subsequent binding of anti-ß(2)GPI from patients with antiphospholipid syndrome (APS). However, the role of the carbohydrate chains of ß(2)GPI in this anti-ß(2)GPI reactivity is poorly understood. We therefore studied the reactivity and inhibition of anti-ß(2)GPI antibodies from APS patients with native, partially glycosylated ß(2)GPI (pdß(2)GPI; without sialic acid) and completely deglycosylated ß(2)GPI (cdß(2)GPI). To determine the potential biologic importance of these glycoforms and their interaction with anti-ß(2)GPI in vitro, stimulation assays were performed with the U937 cell line. Circular dichroism (CD) and fluorescence analysis of the three ß(2)GPI forms were also studied. We found an increased reactivity of anti-ß(2)GPI against pdß(2)GPI and cdß(2)GPI compared to native ß(2)GPI. Both deglycosylated ß(2)GPI isoforms showed higher inhibition of the anti-ß(2)GPI reactivity than the native protein in soluble-phase. Likewise, the antibody/ß(2)GPI/glycoform complexes increased the synthesis of IL-6, IFNγ and TNFα and the expression of HLA-DR, CD14 and CD11c in U937 cells. CD and fluorescence studies of the glycoforms yielded considerable changes in the fluorescence signals. Our work suggests that the partial or complete removal of the carbohydrate chains uncover cryptic epitopes present in ß(2)GPI. The differentiation and increased synthesis of pro-inflammatory cytokines by U937 cells in vitro may have pathogenetic implications.

The role of lupus anticoagulant and triple marker positivity as risk factors for rethrombosis in patients with primary antiphospholipid syndrome.

OBJECTIVES: To ascertain rethrombotic risk factors in patients with primary antiphospholipid syndrome (PAPS). METHODS: We retrospectively evaluated 95 patients according to their rethrombotic status. We registered anticoagulation (OA) status, comorbidities, traditional thrombotic factors, prevalence of aCL (IgG-IgM), anti-ß2GP-I (IgG-IgM), LA and triple marker positivity (LA, aCL and anti-ß2GP-I). RESULTS: Forty-two patients had rethrombosis and 53 were rethrombosis-free. The median follow-up was 4.5 (0.3-26) years. There were no differences in comorbidities and traditional thrombotic factors. Patients with rethrombosis had more frequently LA (62% vs. 40%, p=0.04), were younger (41 vs. 47 years, p=0.01) and received less frequently OA (23% vs. 54%, p=0.002). A logistic regression analysis showed that the OA status (OR 0.17, 95% CI 0.05-0.57, p=0.004) and age (OR 0.94, 95% CI 0.90-0.98, p=0.01) remained significant. Patients who discontinued OA and developed rethrombosis (Group 1, n=32) vs. patients who discontinued OA, but remained rethrombosis-free (Group 2, n=24) were also analysed. We found a higher prevalence of LA and triple marker positivity in Group 1 (67% vs. 31%; OR= 4.5, 95% CI 1.3-14.9, p= 0.01 and 57% vs. 27%; OR 3.6, 95% CI 1.7-12; p=0.03), respectively. Both variables remained associated with rethrombosis when compared with the overall rethrombosis group vs. Group 2 (LA 62% vs. 31%, OR= 3.6 95% CI 1.1-11.2, p=0.03; triple marker 54% vs. 27%; OR 32 95% CI 1.01-10.2, p=0.05). CONCLUSIONS: LA positivity and triple aPL positivity confer a more severe risk of rethrombosis in PAPS patients, irrespective of their anticoagulation status and known conventional risk factors.

Antiphospholipid-associated thrombocytopenia or autoimmune hemolytic anemia in patients with or without definite primary antiphospholipid syndrome according to the Sapporo revised classification criteria: a 6-year follow-up study.

The updated Sapporo classification criteria for antiphospholipid syndrome (APS) only include thrombosis or pregnancy morbidity as clinical criteria. To test this notion, we studied 55 patients (80% women) with hematologic manifestations. All fulfilled the laboratory criteria for primary APS. Thirty-five patients (64%) had thrombocytopenia, 14 (25%) had autoimmune hemolytic anemia, and 6 (11%) had both. Twenty-five patients (22 women, 88%) also fulfilled one clinical criterion for APS after a median follow-up of 13.2 years (range, 1.45-37 years), whereas the remaining 30 patients (22 women, 73%) have not had any thrombotic event nor pregnancy morbidity after a median follow-up of 5.4 years (range, 0.12-24 years). No patient developed systemic lupus erythematosus during follow-up. The hematologic manifestation was asynchronous with the APS onset in 84% of patients. The response to treatment was similar regardless of the APS status. Patients with definite APS were more frequently positive for the lupus anticoagulant (63%) than lupus anticoagulant-positive patients without APS (30%; odds ratio, 3.5; 95% confidence interval, 1.07-11.4; P < .02). Anticardiolipin or anti-ß(2)-glycoprotein-I antibodies were highly prevalent among the study groups. Our study suggests that, depending upon their antiphospholipid profile, patients with hemocytopenias appear to comprise a peculiar subset of patients with APS; some develop thrombotic and/or obstetric APS whereas others continue with hematologic APS.

Anti-beta(2)GP-I and anti-prothrombin antibodies generated by phage display.

This chapter describes the construction and screening of a library of single-chain variable fragments (svFv) derived from patients with autoimmune disease. The methods cover the isolation of mononuclear cells from peripheral blood, preparation of RNA, and recovery of immunoglobulin-coding sequences by polymerase chain reaction (PCR). Cloning into a phage display vector and screening of the scFv display library by a simple panning procedure are described. These methods are applicable to library construction from any patient group or (with alternative primer sets) any mammalian species.

Prevalence and associations of anti-phosphatidylserine/prothrombin antibodies with clinical phenotypes in patients with primary antiphospholipid syndrome: aPS/PT antibodies in primary antiphospholipid syndrome.

OBJECTIVE: The clinical significance of anti-phosphatidylserine/prothrombin (aPS/PT) in antiphospholipid syndrome (APS) is still controversial. We assessed the prevalence of aPS/PT antibodies, their association with other anti-phospholipid antibodies (aPL) and with different APS clinical phenotypes. METHODS: We included 95 primary APS patients according to the Sydney classification criteria, and patients with thrombocytopenia and/or hemolytic anemia who also fulfilled the serological APS criteria. We tested aCL, anti-ß2GP-I and aPS/PT antibodies (both IgG and IgM isotypes) and lupus anticoagulant (LA). We used χ2 test, Spearman's correlation coefficient, Mann-Whitney U test and logistic regression. RESULTS: Seventy-seven percent of patients had thrombosis, 50% hematologic involvement and 25% obstetric events (non-exclusive groups). Twenty patients had only hematologic features. The prevalence of IgG and IgM aPS/PT antibodies was 61% and 60%, respectively. Patients with LA+ had a higher prevalence and higher titers of IgG and IgM aPS/PT antibodies. aPS/PT antibodies correlated with aPL antibodies including LA. IgG aPS/PT antibodies were associated with thrombosis (OR 8.6 [95% CI 2.13-33.8, p = 0.002]) and pure hematologic features (OR 0.2, CI 95% 0.05-0.97, p = 0.004). IgM anti-ß2GP-I antibodies conferred high risk for both hematologic (OR 7.9, 95% CI 1.88-34.61, p = 0.006) and thrombotic involvement (OR 7.4, 95% CI 1.76-31.12, p = 0.006). CONCLUSIONS: aPS/PT antibodies were highly prevalent and correlated with other aPL antibodies. IgG aPTS/PT conferred a high risk for thrombosis, but not for pure hematologic involvement. aPS/PT antibodies may be a useful serological tool in the diagnosis and phenotypic characterization of APS patients.

Cerebral changes in SLE with or without antiphospholipid syndrome. a case-control MRI study.

BACKGROUND: To determine and characterize the prevalence of cerebral changes on MRI in patients with antiphospholipid syndrome (APLS) within systemic lupus erythematosus (SLE). METHODS: Seventy-one patients with SLE were prospectively studied with brain MRI: 32 with definite APLS and 39 without. Atrophy, ventricular enlargement, leukoaraiosis, interuncal distance, Evans' index, infarcts, and white matter hyperintensities (WMH) were analyzed. Demographic data, treatment, and SLE activity were analyzed. RESULTS: Groups were similar in age (32.4 vs. 32.8 years old; P= non-significant [NS]), and gender. Duration of disease was longer in patients with APLS (87.3 vs. 55.4 months; P= .064). Cortical atrophy was common in both groups (68.7% vs. 89.7%; P= NS). Leukoaraiosis was present in only 3 patients (9.4%; P= .08), all in the APLS group. WMH were found in more than 40% of the patients from both groups. Infarcts (21.9% vs. 2.6%; P= .019) and infarcts plus WHM (12.5% vs. 0; P= .037) were more common in patients with APLS. CONCLUSIONS: Although a higher prevalence of neurological involvement in SLE has been reported in APLS patients, we found gross brain changes to be similar between groups. Strokes and leukoaraiosis were more common in the APLS group, consistent with the idea of an APLS-induced prothrombotic state.

Autoimmune inflammation from the Th17 perspective.

Recent studies demonstrated an IL-17-producer CD4+ T cell subpopulation, termed Th17, distinct from Th1 and Th2. It represents a different pro-inflammatory Th-cell lineage. This notion is supported by gene-targeted mice studies. Mice lacking IL-23 (p19-/-) do not develop experimental autoimmune encephalomyelitis (EAE) or collagen-induced arthritis (CIA), while knockout mice for the Th1 cytokine IL-12 (p35-/-) strongly develop both autoimmune diseases. Disease resistance by IL-23 knockout mice correlates well with the absence of IL-17-producing CD4(+) T lymphocytes in target organs despite normal presence of antigen-specific-IFN-gamma-producing Th1 cells. This finding may thus explain previous contradictory reports showing that anti-IFN-gamma-treated mice, IFN-gamma- or IFNR-deficient mice develop CIA or EAE. TGF-beta, IL-6 and IL-1 are the differentiation factors of Th17 cells. IL-23 is dispensable for this function, but necessary for Th17 expansion and survival. The master regulator that directs the differentiation program of Th17 cells is the orphan nuclear receptor RORgammat. IL-27, a member of the IL-12/IL-23 family, potently inhibits Th17 development. Evidence suggesting rheumatoid arthritis and multiple sclerosis as primarily IL-17 autoimmune inflammatory-mediated diseases is rapidly accumulating. The IL-17/23 axis of inflammation and related molecules may rise as therapeutic targets for treating these and perhaps other autoimmune diseases.

Quality of life in patients with antiphospholipid syndrome is related to disease burden and anticoagulant therapy.

AIM: To evaluate health-related quality of life (HRQoL) in primary antiphospholipid syndrome (PAPS) and correlate it with a crude estimate of accrual organ damage, comorbidity (diabetes mellitus, hypertension and dyslipidemia) and treatment (oral anticoagulation, immunosuppressors and prednisone). METHODS: We assessed HRQoL with the Short-Form 36 (SF-36) and the Lupus Quality of Life instrument (LupusQoL) and the disease burden with a modified Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR SDI). As controls we used SF-36 data from a Mexican general population within the same age range. RESULTS: We included 50 PAPS patients (86% women), mean age 47.6 ± 14.5 years, median disease duration 9.4 years, median SLICC/ACR score of 1 point and 80% had thrombotic events. PAPS patients had lower HRQoL than controls. We found a positive correlation between SF-36 and LupusQoL (r = 0.85, P < 0.0001). The SLICC/ACR SDI correlated negatively with both LupusQoL and SF-36, specifically the peripheral vascular domain (r = -0.29, P = 0.03, for both). Patients on oral anticoagulants (n = 37) had lower LupusQoL, physical functioning, intimate relationships, burden to others and pain scores as well as a lower SF-36 physical functioning score. We did not find differences in HRQoL regarding comorbidities and other treatments. CONCLUSIONS: HRQoL in PAPS was related to burden of the disease specifically at the vascular peripheral area and use of anticoagulants.

Cellular immune response to ß2-glycoprotein-I valine/leucine247 phenotypes in Mexican patients with primary antiphospholipid syndrome.

Homozygote genotype V247 of the ß2-glycoprotein-I (ß2GP-I) gene has been associated with anti-ß2GP-I and thrombosis in patients with primary anti-phospholipid syndrome APS (PAPS). However, the cellular immune response to ß2GP-I247 has been little studied. OBJECTIVE: To evaluate the immune cellular proliferation in response to native and non-native ß2GP-I247 valine/leucine phenotype from Mexican patients with PAPS. METHODS: We studied 10 patients with PAPS and 10 healthy control subjects (HC). The polymorphism at position 247 of the ß2GP-I gene was determined by PCR-RFLP and the corresponding ß2GP-I protein was subsequently purified from normal human plasma by affinity chromatography. PBMC purified from patients and controls were stimulated with ß2GP-I under native and in non native (reduced) conditions. We also determined the anti-ß2GP-I production in vitro by B cell clones (EBV) generated in cocultures experiments. Differential Scanning Calorimetry (DSC) was studied to determine the structural differences between the ß2GP-I247 valine/leucine isoforms. Cytokine profile (IL-2, IL-4, IL-6, TNFα, INFγ) was evaluated in culture supernatants. RESULTS: PAPS and healthy control PBMCs had a higher proliferative response when stimulated with ß2GP-I under reduced cultures conditions compared to non-denatured conditions. PBMCs response from PAPS patients was higher. We observed more cell proliferation in response to ß2GP-I247 valine/leucine or valine isoforms in non-native conditions. In contrast, this response was not significant against ß2GP-I247 leucine. These findings were T CD4+-dependent. Similar results were obtained with B cell clones derived from PAPS patients, which showed more pronounced proliferation in non native conditions and higher against ß2GP-I247 valine. No differences were found in anti-ß2GP-I production, but high levels of IL-6 in vitro were identified. The structural analysis of both ß2GP-I247 isoforms by DSC showed a major conformational change due to a single mutation in the ß2GP-I variants. CONCLUSIONS: PAPS PBMCs had a higher cellular response against ß2GP-I247 in non-native culture conditions preferentially to the ß2GP-I247 valine phenotype. This effect is T CD4+ dependent and appears to be driven by tertiary structural changes adopted by ß2GP-I247 polymorphism.

The amount of citrullinated proteins in synovial tissue is related to serum anti-cyclic citrullinated peptide (anti-CCP) antibody levels.

The objective of this study was to determine the relationship between citrullinated proteins in synovial tissue with peripheral anti-citrullinated peptides autoantibodies (ACPA) and peptidylarginine deiminase (PADI) PADI2, PADI3, and PADI4 messenger RNA (mRNA) expressions in synovial tissue and fibroblast-like synoviocytes in rheumatoid arthritis (RA) patients. Eleven RA and 12 osteoarthritis (OA) patients who underwent knee replacement surgery were studied. We detected citrullinated proteins in synovial tissue homogenates by western blot and serum ACPA by ELISA to anti-cyclic citrullinated peptide (anti-CCP) antibodies, and PADI2, PADI3, and PADI4 mRNA expressions in synovial tissue and in fibroblast-like synoviocytes. Patients with high amount of citrullinated proteins in synovial tissue (3 out of 7) have high levels of anti-CCP in serum. However, in the remaining 4 patients, the amount of synovial citrullinated proteins was minimal and their sera showed low levels of anti-CCP antibodies. Furthermore, we observed an increase in PADI2 mRNA expression in RA synovial tissue compared with OA patients (p = 0.02). We detected PADI3 mRNA in the synovial tissue of RA patients, but not in the tissue of OA patients. Even though fibroblast-type synoviocytes in RA are not the main source of PADs in the synovial tissue, they express PADI2 mRNA moderately, PADI4 mRNA weakly, while there is no detectable expression of PADI3 mRNA. In conclusion, we found a variety of citrullinated proteins in the synovial tissue of RA patients and the amount of such proteins is related to serum concentration of anti-CCP antibodies. We identified the presence of PADI3 mRNA expression in synovial tissue and PADI2 and PADI4 mRNA expressions in fibroblast-like synoviocytes from patients with RA.

Anti-beta 2-glycoprotein-I antibodies in scFv format.

Phage display was introduced almost 20 years ago. It has been used to produce large amounts of diverse proteins, to analyze protein-ligand interactions, to improve the affinity of proteins for their binding receptors, and to characterize antibody binding sites. The recombinant version of the antibody Fv is termed single-chain variable fragment (scFv). Many large phage libraries have been developed that have yielded antibodies to several hundred antigens, but only 5 human anti-beta2-glycoprotein-I and three anti-prothrombin antibodies in scFV have been so far characterized. Antibodies to beta2GP-I thus generated show 92-94% homology with their nearest germ line genes. Their mutations frequently appear to be independent of antigen. Two anti-prothrombin antibodies show strong crossreactivity with beta2GP-I. Four mouse anti-beta2GP-I scFV show less binding properties than their original counterparts, but had the same capacity of inducing experimental antiphospholipid syndrome. This pathogenicity appears to reside in the V(H)DJ(H)C(H) region of the scFv since the V(H)DJ(H)C(H) regions of pathogenic scFV combined with irrelevant V(L) J(L)C(L) regions retained their pathogenicity while the opposite failed to do so.

Activated protein C resistance and lupus anticoagulant activity induced by plasma and purified monospecific human IgG anti-beta2-glycoprotein-I antibodies.

INTRODUCTION: We investigated the activated protein C resistance (APCR) phenotype and the lupus anticoagulant (LA), activity induced by anti-beta2-glycoprotein-I (anti-beta2GP-I) antibodies. PATIENTS AND METHODS: We studied plasma and sera samples from 29 patients with persistently positive anti-beta2GP-I: 22 with thrombosis (12 with primary APS, 10 with APS secondary to SLE) and seven without thrombosis (all with SLE); 25 healthy subjects were studied as controls. We detected anticardiolipin antibodies (ACA); IgG (and its subclasses) and IgM anti-beta2GP-I, on irradiated and non-irradiated plates by ELISA. APCR was assessed by the activated partial thromboplastin time (APTT)-based assay and by the modified test. The FV Leiden mutation was studied by PCR. LA determination included screening and confirmatory dRVVT. Serum anti-2 GP-I were affinity purified on sepharose columns and their isotype, subclass, and reactivity against various antigens were studied by ELISA. RESULTS: We found that titers of IgG anti-beta2GP-I on irradiated plates were higher than on non-irradiated plates (p = 0.002), IgG2 was the predominant subclass. Fifteen patients (13 with thrombosis) had LA and 15 (also 13 with thrombosis) induced the APCR phenotype. Eleven (all with thrombosis) had both. Two patients were heterozygous for the Leiden mutation. Two purified antibodies, monospecific for beta2GP-I, induced an in vitro APCR phenotype and LA activity. CONCLUSIONS: Our results seem to indicate that the inhibition of the APC anticoagulant function by IgG2 anti-beta2GP-I with LA activity may be one of the responsible mechanisms of thrombophilia in patients with APS.

Release of neutrophil extracellular traps by neutrophils stimulated with antiphospholipid antibodies: a newly identified mechanism of thrombosis in the antiphospholipid syndrome.

OBJECTIVE: Antiphospholipid antibodies (aPL), especially those targeting ß2 -glycoprotein I (ß2 GPI), are well known to activate endothelial cells, monocytes, and platelets, with prothrombotic implications. In contrast, the interaction of aPL with neutrophils has not been extensively studied. Neutrophil extracellular traps (NETs) have recently been recognized as an important activator of the coagulation cascade, as well as an integral component of arterial and venous thrombi. This study was undertaken to determine whether aPL activate neutrophils to release NETs, thereby predisposing to the arterial and venous thrombosis inherent in the antiphospholipid syndrome (APS). METHODS: Neutrophils, sera, and plasma were prepared from patients with primary APS (n = 52) or from healthy volunteers and characterized. No patient had concomitant systemic lupus erythematosus. RESULTS: Sera and plasma from patients with primary APS had elevated levels of both cell-free DNA and NETs, as compared to healthy volunteers. Freshly isolated neutrophils from patients with APS were predisposed to high levels of spontaneous NET release. Further, APS patient sera, as well as IgG purified from APS patients, stimulated NET release from control neutrophils. Human aPL monoclonal antibodies, especially those targeting ß2 GPI, also enhanced NET release. The induction of APS NETs was abrogated with inhibitors of reactive oxygen species formation and Toll-like receptor 4 signaling. Highlighting the potential clinical relevance of these findings, APS NETs promoted thrombin generation. CONCLUSION: Our findings indicate that NET release warrants further investigation as a novel therapeutic target in APS.

Anticardiolipin and anti-beta2-glycoprotein-I antibodies in hypertensive disorders of pregnancy.

BACKGROUND: This study was undertaken in order to determine the frequency of anticardiolipin (aCL) and anti-beta2-glycoprotein-I antibodies (anti-beta2 GP-I) in patients with hypertensive disorders of pregnancy. METHODS: We studied aCL (IgG and IgM) and IgG anti-beta 2 GP-I by ELISA in the serum and IgG aCL and anti-beta 2 GP-I in the urine of 125 women with hypertensive disorders of pregnancy (cases) (75 had preeclampsia, 25 had eclampsia, and 25 had chronic hypertension). One hundred and twenty seven normal women were used as controls. Antibody positivity was defined as above the 90(th) percentile of the controls. RESULTS: We found no differences in frequency of serum anti-beta 2 GP-I or serum and urinary aCL between cases and controls. In contrast, we found that frequency of IgG anti-beta 2 GP-I was higher in the urine of cases (26.1%) compared to controls (9.4%, p = 0.001). Strength of association was stronger for urinary anti-beta2-glycoprotein-I in women with preeclampsia (odds ratio [OR] = 4.3, 95% confidence limit [CI 95%] = 1.95-9.62, p <0.0001). Cases and the subgroup of preeclamptic patients also had higher titers of urinary IgG anti-beta 2 GP-I than control women (p <0.0001). CONCLUSIONS: Our work suggests that urine testing is necessary in order to ascertain whether antibodies to beta(2)GP-I are associated with preeclampsia.

Anti-cardiolipin, anti-cardiolipin plus bovine, or human beta(2)glycoprotein-I and anti-human beta(2)glycoprotein-I antibodies in a healthy infant population.

BACKGROUND: Pathogenic antiphospholipid antibodies studies are usually conducted on populations of adults. Studies involving normal children are scant. METHODS: Antibody reactivity against CL alone (true aCL), CL-complexed to bovine beta(2)GP-I (aCL-bovine beta(2)GP-I), or human (aCL-human beta(2)GP-I) beta(2)GP-I, or to phospholipid-free human beta(2)GP-I (anti-human beta(2)GP-I) was determined by ELISA in serum samples from 360 Mexican children ranging from 1 month through 8 years of age. RESULTS: Statistical analysis of variance and rankings of Kruskal-Wallis demonstrated no significant difference in all tested antibody activities between ages and genders of the study population. Values are presented as a percentile distribution included between 5 and 99, corresponding to the percentages of the studied population. Normal arbitrary units (AU) for IgG, IgA, and IgM true aCL that correspond to the 95 and 99 percentiles are as follows: 2.15 and 3.5; 2.35 and 5.0, and 3.15 and 4.5, respectively. IgG, IgA, and IgM aCL-bovine beta(2)GP-I activities are 2.6 and 5.0, 3.0 and 5.0, and 2.7 and 6.0 AU, respectively, while IgG activities of aCL-bovine and human beta(2)GP-I are 1.45 and 1.80, respectively. Normal values for IgG anti-human beta(2)GP-I are 1.85 AU. CONCLUSIONS: While elevated serum levels of antibodies to CL and/or beta(2)GP-I have been associated with thrombotic and hematologic manifestations, the majority of reports deal with adult populations. We report the cut-off values (in AU, international PL units, and international units for beta(2)GP-I) of the specific serologic response of true aCL, aCL-bovine beta(2)GP-I, aCL-human beta(2)GP-I, and anti-human beta(2)GP-I in healthy Mexican children.