Flavio Allegri

Anti-beta 2-glycoprotein I antibodies: a marker of antiphospholipid syndrome?

Anticardiolipin (aCL) and anti-beta2-glycoprotein I(antiβ2GPI) antibodies have been shown in animal models as not cross-reacting antibody populations. This observation prompted us to prove if anti-β2GPI exist in human sera by using a reliable method and then to investigate if these are independent from aCl antibodies. We have developed a new ELISA for the detection of anti-β2GPI antibodies employing the coating of the protein in carbonate buffer to irradiated microtitre plates and the filtration of serum samples, that makes irrelevant the binding to the uncoated wells. IgG F(ab)2 fragments from IgG positive sera were shown bind β2GPI, providing that the binding was a specific antibody binding, mediated by the antigen binding site of the antibody molecule; moreover the antibodies were not able to differentiate native and delipidated β2GPI coated plates, making a possible role of a phospholipid contaminant unlikely. On the other hand, the phosphorus content of native as well as delipitated β2GPI was undetectable. IgG, but not IgM, anti-β2GPI antibodies were classically inhibited by the addition of soluble β2GPI, while cardiolipin liposomes appear to modify the reaction in a completely different way, possibly by the described interaction between cardiolipin and β2GPI. The application of the new ELISA to the study of patients has shown that: (1) the presence of anti-β2GPI is statistically associated with the presence of aCL antibodies (P < 0.0001), (2) anti-β2GPI antibodies are related to the classical features of antiphospholipid syndrome (thrombosis: P < 0.001; fetal loss: P < 0.001) while, in this series of patients, aCl antibodies are not (thrombosis: P < 0.126; fetal loss: P < 0.061).

Anti-DNA antibodies: a diagnostic and prognostic tool for systemic lupus erythematosus?

The clinical impact of anti-DNA antibodies lies on their diagnostic power for systemic lupus erythematosus (SLE), being a formal classification criterion. In spite of such a disease association, low-avidity anti-DNA antibodies might also be part of the natural autoantibody repertoire. Their switch to pathogenic high-avidity autoantibodies is the result of the autoimmune process leading to SLE. Anti-DNA antibodies were shown to play a role in SLE pathogenesis and particularly in kidney damage. Accordingly, antibody titres might fluctuate in relation to disease activity, but their prognostic value for flares is still debated. Several methods for anti-DNA detection were described and there is evidence that the assays identify different antibodies with different prognostic value. The results of a multicenter study on four different routine tests for anti-dsDNA antibody detection showed that: (i) Farr assay displays the best diagnostic specificity/sensitivity for SLE, followed by Crithidia luciliae method (CLIFT), (ii) the new generation of solid phase assay (EliA) shows an increased sensibility versus the classical enzyme linked immune assay (ELISA) but a decreased specificity. Antibody titre detected by EliA and Farr assay correlated with disease activity. These findings would suggest that more than one assay should be useful for SLE diagnosis and monitoring.

European registry of babies born to mothers with antiphospholipid syndrome

Objectives This study aimed to describe the long-term outcome and immunological status of children born to mothers with antiphospholipid syndrome, to determine the factors responsible for childhood abnormalities, and to correlate the childs immunological profile with their mothers. Methods A prospective follow-up of a European multicentre cohort was conducted. The follow-up consisted of clinical examination, growth data, neurodevelopmental milestones and antiphospholipid antibodies (APL) screening. Children were examined at 3, 9, 24 months and 5 years. Results 134 children were analysed (female sex in 65 cases, birth weight 3000±500 g, height 48±3 cm). Sixteen per cent had a preterm birth (<37 weeks; n=22), and 14% weighted less than 2500 g at birth (n=19). Neonatal complications were noted in 18 cases (13%), with five infections (4%). During the 5-year follow-up, no thrombosis or systemic lupus erythematosus (SLE) was noted. Four children displayed behavioural abnormalities, which consisted of autism, hyperactive behaviour, feeding disorder with language delay and axial hypotony with psychomotor delay. At birth lupus anticoagulant was present in four (4%), anticardiolipin antibodies (ACL) IgG in 18 (16%), anti-β2 glycoprotein-I (anti-β2GPI) IgG/M in 16 (15%) and three (3%), respectively. ACL IgG and anti-β2GPI disappeared at 6 months in nine (17%) and nine (18%), whereas APL persisted in 10% of children. ACL and anti-β2GPI IgG were correlated with the same mothers antibodies before 6 months of age (p<0.05). Conclusion Despite the presence of APL in children, thrombosis or SLE were not observed. The presence of neurodevelopmental abnormalities seems to be more important in these children, and could justify long-term follow-up.

Anticardiolipin and anti-β2GPI antibodies in a large series of European patients with systemic lupus erythematosus

Objective. To test the prevalences and the clinical associations of anticardiolipin (aCL) and anti-β2GPI (aβ2GPI) antibodies in a large series of European patients with systemic lupus erythematosus (SLE). Methods. 574 SLE patients from 7 European countries were tested for aCL and aβ2GPI by ELISA methods. Results. aCL of IgG, IgM, and IgA isotypes were detected in 22.8%, 14%, and 13.9% of the patients, respectively. IgG and IgM aβ2GPI were detected in 20% of the patients. The presence of aCL was highly associated with the presence of aβ2GPI. Medium-high titer IgG aCL and aβ2GPI were associated with thrombosis, with similar sensitivity, specificity, and positive predictive value. When present at mediumhigh titer, IgG aCL were associated with thrombocytopenia, IgM aCL with hemolytic anemia, and cerebrovascular accidents, IgA aCL with livedo reticularis and Raynauds phenomenon. Conclusion. aCL, when present at medium-high titer, are as important as ab2GPI, as a risk factor for thrombosis. Medium-high titer a...

Antinucleosome antibodies in primary antiphospholipid syndrome: A hint at systemic autoimmunity?

BACKGROUND Antinucleosome antibodies (anti-NCS) are reported to be highly sensitive and specific for systemic lupus erythematosus (SLE) and to correlate with disease activity. They may appear in early stages of the disease, in particular before anti-dsDNA antibodies, being a potential marker for identifying patients susceptible to SLE. Patients with primary antiphospholipid syndrome (PAPS) may develop full-blown SLE but there is no evidence for markers predictive for that. AIM To evaluate whether anti-NCS may be predictors for full-blown or lupus like disease (LL) in a cohort of PAPS patients. METHODS A multicentric cohort of 105 PAPS patients was tested for IgG/IgM anti-NCS by using a home made assay with H1-stripped chromatin as antigen. RESULTS Eighty-one out of 105 (77%) of the patients were positive for anti-NCS; medium-high titre results were present only in 49/105 (46%). Anti-NCS were more frequently detected in PAPS+LL, but no relationship with clinical/serological features was found, except for a weak correlation with anti-dsDNA antibodies. Two PAPS patients evolved into full-blown SLE during the follow-up and displayed high titre anti-NCS many years before. CONCLUSIONS Our findings suggest that anti-NCS might be added to the mosaic of autoimmune phenomena characterizing PAPS patients and in particular those with more chance to evolve to SLE.

Diagnostic value of anti-mutated citrullinated vimentin in comparison to anti-cyclic citrullinated peptide and anti-viral citrullinated peptide 2 antibodies in rheumatoid arthritis: An Italian multicentric study and review of the literature

In the last years, the detection of antibodies (Abs) against citrullinated peptides (ACPA) has largely replaced rheumatoid factor (RF) as the most helpful biomarker in the diagnosis of rheumatoid arthritis (RA). Current assays detect ACPA reactivity with epitopes on various different citrullinated proteins. Among these, anti-cyclic citrullinated peptide (CCP) Abs have been widely demonstrated to be an important diagnostic and prognostic tool because of their high specificity. Recently, citrullinated vimentin, a protein highly released in synovial microenvironment, has been identified as potential autoantigen in the pathophysiology of RA and an enzyme-linked immunosorbent assay (ELISA) for the detection of Abs directed against a mutated citrullinated vimentin (anti-MCV) was developed. Several recent studies evaluating the characteristics of anti-MCV in comparison to anti-CCP Abs, have given conflicting results. Anti-MCV have been demonstrated to perform better than anti-CCP as predictor of radiographic damage. Conversely, its additional diagnostic and prognostic role in comparison to anti-CCP in both early and established RA is controversial. Aim of this study was to evaluate the diagnostic performance of anti-MCV in RA and to compare it to anti-CCP and the recently developed assay targeting viral citrullinated peptide 2 (VCP2) in a large cohort of RA patients (n=285), healthy subjects and other disease controls (n=227). Anti-MCV resulted to have a sensitivity of 59% and a specificity of 92%. In comparison, anti-CCP and anti-VCP2 displayed a sensitivity of 77% and 61% and a specificity of 96% and 95%, respectively. Of interest, at the manufacturer recommended cutoff value of 20U/mL, a high percentage of healthy subjects as well as Epstein Barr (EBV) and hepatitis C (HCV) virus infected patients resulted anti-MCV positive. In our large cohort of RA patients, anti-MCV demonstrated lower sensitivity than anti-CCP and VCP2 test, thus not allowing to confirm previously published data. Moreover, the high rate of detection in infectious diseases limits its diagnostic value in undifferentiated arthritis.

Clinical Characterization of Antiphospholipid Syndrome by Detection of IgG Antibodies Against β2‐Glycoprotein I Domain 1 and Domain 4/5: Ratio of Anti–Domain 1 to Anti–Domain 4/5 As a Useful New Biomarker for Antiphospholipid Syndrome

It has been suggested that only antibodies against domain 1 (D1) of β2‐glycoprotein I (β2GPI) are pathogenic and diagnostic. The role of antibodies against other β2GPI domains is still debated. This study was undertaken to evaluate the clinical relevance of domain specificity profiling of anti‐β2GPI IgG antibodies in antiphospholipid syndrome (APS) patients and in control groups of patients with systemic autoimmune rheumatic diseases and in asymptomatic antiphospholipid antibody (aPL) carriers.

Anticardiolipin and anti-β2GPI antibodies in a large series of European patients with systemic lupus erythematosus : Prevalence and clinical associations

Objective: To test the prevalences and the clinical associations of anticardiolipin (aCL) and anti-β 2 GPI (aβ 2 GPI) antibodies in a large series of European patients with systemic lupus erythematosus (SLE). Methods: 574 SLE patients from 7 European countries were tested for aCL and aβ 2 GPI by ELISA methods. Results: aCL of IgG, IgM, and IgA isotypes were detected in 22.8%, 14%, and 13.9% of the patients, respectively. IgG and IgM aβ 2 GPI were detected in 20% of the patients. The presence of aCL was highly associated with the presence of aβ 2 GPI. Medium-high titer IgG aCL and aβ 2 GPI were associated with thrombosis, with similar sensitivity, specificity, and positive predictive value. When present at medium-high titer, IgG aCL were associated with thrombocytopenia, IgM aCL with hemolytic anemia, and cerebrovascular accidents, IgA aCL with livedo reticularis and Raynauds phenomenon. Conclusions: aCL, when present at medium-high titer, are as important as aβ 2 GPI, as a risk factor for thrombosis. Medium-high titer aCL, but not aβ 2 GPI, are associated with other clinical features of the antiphospholipid syndrome.

Laboratory criteria of the obstetrical antiphospholipid syndrome - Data from a multicentric prospective European women cohort

A debate on updating the laboratory criteria of antiphospholipid syndrome (APS) was recently opened in view to lower the risk of over diagnosis of the syndrome. Based on data related to thrombotic APS, it proposes the exclusion of anticardiolipin antibodies (aCL) and anti-beta2-glycoprotein 1 (a-beta2-GPI) IgM detection. Here, we examine this possibility in a study which focuses on obstetrical APS (OAPS). We report new data on a prospective multicenter European cohort of 109 pregnant women having APS. Among them, 73 had purely obstetrical APS, not associated to autoimmune diseases or thrombosis. Isolated antibodies and isolated aCL positivity were present in 50/109 (46%) and in 34/109 (31%) of the women, respectively. An isolated a-beta2-GPI IgM was present in three women. These results suggest that aCL and a-beta2-GPI IgM cannot be dropped for the diagnosis and classification of OAPS. The low level of some antibodies associated with severe obstetrical complications raise the issue of keeping or not the same laboratory criteria for OAPS and for thrombotic APS and whether additional criteria after large prospective studies could further improve diagnosis.

Vitamin D and antiphospholipid syndrome

Vitamin D (vitD) has been shown to have multiple immunomodulatory properties. Hypovitaminosis D has been described in many systemic autoimmune diseases. Antiphospholipid syndrome (APS), an autoimmune disease characterized by immune-mediated thrombosis and pregnancy loss, is a peculiar model for studying vitD, since these patients do not usually have a full-blown autoimmune disease, nor do they have particular restrictions regarding sun exposure. We assessed 25-OH vitD levels in 115 APS and 128 normal healthy donors (NHD) with the LIAISON® chemiluminescent immunoassay by DiaSorin (Italy). Median values were lower in APS patients than in NHD, with the greatest difference occurring during summertime (p < 0.01), suggesting that APS patients may be somehow prevented from vitD generation upon sun exposure. In our cohort, APS patients may have been instructed to use sunscreens in the presence of positive antinuclear antibodies (ANA). Comparing patients with positive and negative ANA, we found comparable vitD levels during the summer. By subdividing APS patients according to clinical features, thrombotic APS patients showed significantly lower levels than did pure obstetric APS patients (p < 0.01). In conclusion, our study confirms previous reports of hypovitaminosis D in APS patients, making them more similar to patients with other systemic autoimmune diseases than NHD. Hypovitaminosis D may be part of the mosaic of factors that determine autoimmunity, rather than a consequence of chronic disease and its treatment. The observation that patients with thrombotic APS, an aggressive phenotype, may be more deficient than those with exclusive obstetric manifestations fits well with the beneficial effects of vitD on thrombosis described both in vitro and in vivo. Therefore, there may be a rationale to assess the efficacy of vitD supplementation in APS patients.