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Biomedical subjects

A Tincani

Publications and source records attributed to A Tincani.

At least 73 records · Page 4Linked to original sources
PubMed1998

Differential effects of anti-beta2-glycoprotein I antibodies on endothelial cells and on the manifestations of experimental antiphospholipid syndrome.

BACKGROUND: The antiphospholipid syndrome (APS) entails a prothrombotic state associated with the presence of anticardiolipin antibodies (aCL). aCL were shown to promote endothelial cell and platelet activation and to induce an APS-like syndrome in mice when administered intravenously. Recent data suggest that aCL target the plasma cofactor beta2-glycoprotein I (beta2GPI) rather than negatively charged phospholipids. However, it has not been determined whether different epitope-specific anti-beta2GPI antibodies obtained from one patient possess pathogenic properties. METHODS AND RESULTS: Three beta2GPI-binding IgM monoclonal antibodies (mAbs) (ILA-1, ILA-3, and ILA-4) were cloned from a patient with APS. The three antibodies were shown to bind beta2GPI immobilized on irradiated plates, yet only ILA-1 bound beta2GPI coated onto nonirradiated plates. Furthermore, when using the anti-beta2GPI enzyme-linked immunosorbent assay, ILA-1 was the only mAb inhibited by fluid phase beta2GPI. ILA-1 and ILA-3, but not ILA-4, induced adherence of U937 cells to endothelial cells in vitro (reflecting activation of endothelial cells). mAbs ILA-1 and ILA-3 as opposed to ILA-4 induced significant expression of adhesion molecules when preincubated with human umbilical vein endothelial cells. Passive administration of ILA-1 and ILA-3 to pregnant BALB/c mice induced clinical findings consistent with APS (increased fetal resorptions, reduced platelet counts, and prolonged activated partial thromboplastin time), whereas both ILA-4 and the control human IgM did not produce similar effects. CONCLUSIONS: The results of the study demonstrate the differential effects of various populations of anti-beta2GPI antibodies on endothelial cell activation and on experimental APS.

Adult↗
PubMed1998

Apoptotic cell clearance in systemic lupus erythematosus. I. Opsonization by antiphospholipid antibodies.

OBJECTIVE: To verify whether antiphospholipid antibodies (aPL) recognize and opsonize apoptotic human cells. METHODS: Apoptosis was induced via CD95 crosslinking or ultraviolet irradiation. IgG and anti-beta2-glycoprotein I (anti-beta2-GPI) antibodies were purified from patient sera by affinity chromatography. The aPL that bound to apoptotic cells were assessed by flow cytometry, and the subdomains recognized were identified by confocal microscopy. Human macrophages were derived from monocytes, and their ability to phagocytose 3H-labeled apoptotic bodies, whether opsonized or not opsonized by aPL, was assessed. Tumor necrosis factor alpha (TNF alpha) secretion was evaluated by enzyme-linked immunosorbent assay. RESULTS: The aPL, but not control Ig or Ig from aPL-negative patients, bound to apoptotic cells, but not to viable cells. Nuclear antigens were not recognized. Opsonization of apoptotic cells by aPL substantially enhanced recognition and binding by scavenger macrophages, with massive TNF alpha secretion. CONCLUSION: Antiphospholipid antibodies facilitate apoptotic cell clearance by macrophages and trigger TNF alpha release, possibly enhancing the immunogenicity of the autoantigens they contain.

Antibodies, Antiphospholipid↗
PubMed1998

Apoptotic cell clearance in systemic lupus erythematosus. II. Role of beta2-glycoprotein I.

OBJECTIVE: To analyze the contribution of beta2-glycoprotein I (beta2-GPI) to apoptotic cell recognition by antiphospholipid antibodies (aPL) and macrophages from patients with autoimmune disease. METHODS: Phosphatidylserine expression by Jurkat cells undergoing apoptosis upon CD95 crosslinking or ultraviolet irradiation was verified by confocal microscopy of cells stained with fluorescein isothiocyanate-labeled annexin V. Beta2-GPI was purified by heparin/cationic-exchange chromatography and was biotinylated or used to purify beta2-GPI-specific antibodies by affinity chromatography. Binding to apoptotic cells was assessed by flow cytometry. The clearance of 3H-labeled, apoptotic cells by macrophages was assessed by beta counting. RESULTS: The array of epitopes generated by beta2-GPI association with apoptotic cells specifically targets their recognition and is required for their opsonization by human aPL. Nevertheless, beta2-GPI is not required for apoptotic cell clearance by human macrophages in the absence of aPL. CONCLUSION: The proinflammatory clearance of aPL-opsonized apoptotic cells, but not the nonphlogistic clearance of apoptotic cells by scavenger macrophages, depends on beta2-GPI.

Antibodies, Antiphospholipid↗
PubMed1998

Dendritic cells preferentially internalize apoptotic cells opsonized by anti-beta2-glycoprotein I antibodies.

Dendritic cells (DC) are potent antigen-presenting cells involved in the initiation of immune responses, including those directed towards self antigens. Immature DC capture soluble antigens by macropinocytosis or c-type lectin receptor-mediated endocytosis and particulate by phagocytosis, including Fc receptor-mediated phagocytosis. Apoptosis is accompanied by the clustering of intracellular autoantigens, which are also selectively cleaved and phos-phorylated, and by the exposure of anionic phospholipids (phosphatidyl-serine, PS). Anti-phospholipid antibody (aPL) detection correlates with an increased risk of developing autoimmune syndromes. In this study apoptosis was induced by UV irradiation, growth factor deprivation or exposure to protein synthesis inhibitors of murine cells and verified by confocal microscopy and flow cytometry. Apoptotic cells were recognized by a panel of anti-beta2-glycoprotein I (beta2-GPI) aPL monoclonal antibodies, but not by isotype-matched antibodies. The binding restricted to membrane domains, corresponding to apoptotic blebs, was not affected by the stimulus initiating apoptosis and was specific, since it required the association of the beta2-GPI co-factor to the apoptotic membrane. aPL-binding successfully transformed apoptotic cells in an efficient phagocytic substrate for murine immature DC, possibly skewing their immunogenicity in vivo.

Animals↗
PubMed1998

Anti-mitochondrial M5 type antibody represents one of the serological markers for anti-phospholipid syndrome distinct from anti-cardiolipin and anti-beta2-glycoprotein I antibodies.

The aim of this study was to characterize the antigen specificity and to evaluate the diagnostic and prognostic value of anti-mitochondrial M5 type antibodies (AMA M5). Fifty-eight patients selected on the basis of their AMA M5 positivity were investigated in relationship to their clinical and serological profile. Cross-absorption studies, Western blotting and immunoprecipitation analysis were carried out for AMA M5 antigen specificity characterization. Most patients had a diagnosis of systemic lupus erythematosus (SLE) (65.5%) or of primary anti-phospholipid syndrome (PAPS) (24%); all the patients were positive for IgG or IgM anti-cardiolipin (anti-CL) antibodies and 49% of them also displayed lupus anticoagulant (LA) activity. Anti-beta2-glycoprotein I (beta2-GPI) IgG were detectable in 30/38 sera (78.9%) and IgM in 34/38 (89.4%). While anti-CL and anti-beta2-GPI IgG antibodies were significantly associated with history of thrombosis and fetal loss, AMA M5 displayed a statistical association only for thrombocytopenia and recurrent fetal loss. Absorption with human beta2-GPI both in free solution or in solid phase as well as with CL liposomes or CL/beta2-GPI liposome complexes did not affect AMA M5 fluorescence. While AMA M5 activity is absorbed by whole mitochondrial preparations, no specific reactivities against several human, bovine and rat mitochondrial proteins could be detected in Western blotting and immunoprecipitation studies. AMA M5 appear to be detectable in both primary and secondary APS, displaying a strong association with the presence of thrombocytopenia and fetal loss. Although strictly related to anti-phospholipid antibodies, AMA M5, anti-CL and anti-beta2-GPI antibodies represent distinct serological markers of the APS.

Adolescent↗
PubMed1998

Beta2-glycoprotein I as a 'cofactor' for anti-phospholipid reactivity with endothelial cells.

Beta2-glycoprotein I (beta2GPI) is a cofactor for anti-phospholipid (aPL) binding to cardiolipin (CL)-coated plates. Beta2GPI is also able to bind to endothelial cell (EC) membranes as supported by in-vivo as well as by in-vitro studies. The PL-binding site in the fifth domain of the molecule is involved in the adhesion to endothelium. Actually, specific mutations in this molecular portion abolish endothelium binding and a synthetic peptide spanning the sequence Glu274-Cys288 of the CL-binding site displays comparable adhesion to EC monolayers. Heparan sulphate appears to be one of the anionic EC membrane structures with which cationic beta2GPI interacts, as supported by studies with heparitinase-treated EC. Beta2GPI binding to EC might be related to its activity as endothelial growth factor or as a lipid-carrying glycoprotein. Adhesion of beta2GPI to endothelial membranes offers suitable epitopes for circulating aPL that, once bound, can induce cell activation

Amino Acid Substitution↗
PubMed1998

Anti beta2-glycoprotein I antibodies: clinical significance.

The introduction of anticardiolipin antibody (aCL) assay, described in 1983, was able to focus much attention on the study of patients suffering from thrombosis, repeated fetal loss and thrombocytopenia, and allowing the identification of the so called antiphospholipid syndrome (APS). The identification of beta2 glycoprotein I (beta2GPI) as an essential component of the antigenic complex recognized by aCL suggested that this molecule could be a direct target of the antibody response. Since then, different groups have described ELISAs for the detection of anti beta2GPI antibodies, applied to the clinical evaluation of patients with APS, and showing an overall better specificity. Recently, anti beta2GPI were also shown to bind apoptotic bodies resulting in an alteration of their physiological clearance with the triggering of TNFalpha release. This observation suggests that anti beta2GPI may also modify the immunogenicity of apoptotic bodies and of the autoantigens that they contain.

Antibodies, Anticardiolipin↗
PubMed1997

Endothelial cells as target for antiphospholipid antibodies. Human polyclonal and monoclonal anti-beta 2-glycoprotein I antibodies react in vitro with endothelial cells through adherent beta 2-glycoprotein I and induce endothelial activation.

OBJECTIVE: To investigate the ability of human anti-beta 2-glycoprotein I (anti-beta 2 GPI) antibodies to recognize the cofactor adherent on endothelial cells (EC) and to modulate endothelial functions. METHODS: Six human affinity-purified polyclonal anti-beta 2 GPI IgG and 2 IgM monoclonal antibodies (MAb) were obtained from patients with the antiphospholipid syndrome. The antibodies were tested for their ability to 1) bind to endothelial monolayers through the adherent beta 2 GPI and 2) modulate endothelial adhesion molecule expression and interleukin-6 (IL-6) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) secretion. RESULTS: The affinity-purified IgG and the MAb with anti-beta 2 GPI activity, but not the respective controls, displayed EC binding, which declined on cells incubated in serum-free medium and was restored in a dose-dependent manner by exogenous human beta 2 GPI. After EC binding, both polyclonal and monoclonal antibodies up-regulated adhesion molecule expression. Anti-beta 2 GPI MAb also significantly increased IL-6 and 6-keto-PGF1 alpha secretion. CONCLUSION: These findings support the hypothesis that anti-beta 2 GPI antibodies bind and activate EC through the adherent cofactor beta 2 GPI, likely leading to a procoagulant state.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Anti-beta 2 glycoprotein I antibodies in a general obstetric population: preliminary results on the prevalence and correlation with pregnancy outcome. Anti-beta2 glycoprotein I antibodies are associated with some obstetrical complications, mainly preeclampsia-eclampsia.

OBJECTIVE: To evaluate the prevalence in normal pregnancies of anti-32 glycoprotein I (anti-beta2GPI) antibodies, and their association with obstetrical complications. STUDY DESIGN: Prospective study of anti-beta2GPI and anticardiolipin (CL) antibodies in 510 healthy pregnant women at 15-18 weeks. According to the results, women were categorized into three groups: group I, negative for both antibodies; group II, positive for anti-beta2GPI antibodies; group III, positive for aCL only. The rates of fetal loss, abruptio placentae, preeclampsia-eclampsia, and fetal growth retardation were compared in the three groups. RESULTS: Anti-beta2GPI antibodies were found in 20 women (3.9%) and aCL in 8 patients (1.6%). Obstetrical complications were more frequent, even if not significantly different, in group II, 15%, than in group I, 4.1% (difference 10.9%; 95% confidence interval (CI): 1.6-20.2%; p=0.0575), while no complications were seen in group III. Preeclampsia-eclampsia were significantly more frequent in group II (10%) than in group I (0.8%; difference 9.2%; 95% CI: 4.4-14%; p=0.021). The prevalence of fetal growth retardation was not significantly different in the two groups (5% vs. 2%, respectively). COMMENT: Our findings indicate that anti-beta2GPI antibodies are associated with some obstetrical complications, mainly preeclampsia-eclampsia, even if more conventional antiphospholipid antibodies are not present. This observation suggests that these antibodies should be investigated in such cases, in order to improve the outcome of subsequent pregnancies, as well as in women with a history of early and/or recurrent severe preeclampsia in order to start a prophylactic treatment (i.e. low-dose aspirin or heparin).

Abruptio Placentae↗
PubMed1997

Endothelial cells as a target for antiphospholipid antibodies: role of anti-beta 2 glycoprotein I antibodies.

PROBLEM: To investigate the role of the plasma cofactor for antiphospholipid antibodies in antibody binding to endothelial cells. METHOD OF STUDY: a) Evaluation of endothelial cell binding of polyclonal and monoclonal anti-beta 2 glycoprotein I antibodies; and b) study of the effects of antibody binding: adhesion molecule expression, leukocyte adhesion, and interleukin-1 beta secretion. RESULTS: Anti-beta 2 glycoprotein I antibodies bind endothelial cell monolayers in vitro by reacting with the cofactor adhered to the cell membranes. Antibody binding induces an up-regulation of adhesion molecules, favours leukocyte adherence, and increases interleukin-1 beta secretion. Interleukin-1 beta plays an active role to mediate adhesion molecule expression through an autocrine loop, as shown by the inhibitory effect of interleukin 1 receptor antagonist. CONCLUSIONS: Antiphospholipid antibodies do react with endothelium through the co-factor adhered to their cell membranes and induces a pro-adhesive cell phenotype.

Animals↗
PubMed1997

Utilization of dilute Russell's viper venom time to detect autoantibodies against beta 2-glycoprotein I which express anticoagulant activity in the presence but not in the absence of exogenous phospholipids.

Lupus anticoagulant (LA) is a general term to define immunoglobulins interfering with phospholipid-dependent coagulation tests. It is now clear that the phospholipid-dependence of some LA is related to the presence of the phospholipid-binding plasma protein beta 2-glycoprotein I (beta 2-GPI) and that autoantibodies to beta 2-GPI might represent a specific category of LA. To verify this hypothesis we have purified IgG autoantibodies to beta 2-GPI from plasma of 6 patients with antiphospholipid antibody syndrome, by means of agarose-immobilized human beta 2-GPI. All 6 preparations tested positive in anti-beta 2-GPI IgG antibody ELISA and showed a marked LA activity by prolonging dilute Russell Viper Venom Time (dRVVT) from a minimum of 5.3 s in patient # 1 to a maximum of 41.1 s in patient # 3. These IgG preparations behaved as typical LA, with this activity tending to disappear in the presence of increasing phospholipid (PL) concentrations. Moreover, the LA activity of the IgG preparations was not detectable in the absence of PL, in which case the ratio between dRVVT obtained in the presence and absence of IgG autoantibodies to beta 2-GPI was close to 1. This pattern was confirmed by using plasma from patients with antiphospholipid antibody syndrome testing positive for anti-beta 2-GPI IgG antibodies. These findings suggest that dRVVT performed both in the presence and absence of PL might constitute a sensitive screening test to detect specific antibodies with LA activity.

Autoantibodies↗
PubMed1996

The anti-beta2-glycoprotein I activity in human anti-phospholipid syndrome sera is due to monoreactive low-affinity autoantibodies directed to epitopes located on native beta2-glycoprotein I and preserved during species' evolution.

To characterize the reactivity pattern of Abs directed to beta2-glycoprotein I (anti-beta2GPI) in patients with anti-phospholipid syndrome, we have purified anti-beta2GPI Abs by affinity chromatography using the IgG fractions from sera of five different anti-phospholipid syndrome patients. Affinity-purified anti-beta2GPI were shown to be representative of Abs found in human sera because their activity could be virtually abolished from the IgG preparations after repeated absorptions on immobilized human beta2GPI column. Our results show that affinity-purified anti-beta2GPI: 1) do react with beta2GPI in the absence of any phospholipid, as demonstrated by the lack of phosphorus contaminant in the employed reagents, as well as by their comparable binding activity before and after extensive delipidation procedure; 2) can recognize beta2GPI regardless of its origin from different animal species; 3) are able to bind soluble beta2GPI with a mean Kd value of 4.65 x 10(-6) M (range 3, 4-7, 2 x 10(-6) M); 4) significantly enhance their binding avidity when beta2GPI is linked to a solid support; and 5) appear to be mainly monoreactive autoantibodies. In conclusion, we have shown that human polyclonal anti-beta2GPI are low affinity, mainly monoreactive autoantibodies directed to an epitope located on native beta2GPI, preserved along the species evolution.

Adolescent↗
PubMed1996

Anti-endothelial cell IgG antibodies from patients with Wegener's granulomatosis bind to human endothelial cells in vitro and induce adhesion molecule expression and cytokine secretion.

OBJECTIVE: To elucidate the role of anti-endothelial cell antibodies (AECA) in vascular inflammation in patients with Wegener's granulomatosis (WG). METHODS: IgG fractions from 3 AECA-positive WG patients, IgG from 3 AECA-negative WG patients, and IgG from healthy donors were tested for their ability to: a) bind to endothelial cells and to display complement-dependent or antibody-dependent cellular cytotoxicity, b) modulate cell membrane expression of adhesion molecules, as evaluated by cytofluorometry and by immunoenzymatic assay, and c) induce the secretion of interleukin-1 beta (IL-1 beta), IL-6, IL-8, and monocyte chemotactic protein 1 (MCP-1). RESULTS: We found that AECA IgG from WG patients do not display any significant cytotoxicity but are able to up-regulate the expression of E-selectin, intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 and to induce the secretion of IL-1 beta, IL-6, IL-8, and MCP-1. CONCLUSION: AECA in patients with WG could play a potential pathogenetic role by activating endothelial cells, and thus facilitating leukocyte recruitment and adhesion to endothelial surfaces, rather than by displaying a cytotoxic activity.

Autoantibodies↗
PubMed1996

Aspirin-interleukin-3 interrelationships in patients with anti-phospholipid syndrome.

PROBLEM: Previously we reported on the generation of experimental anti-phospholipid syndrome (APS) in mice. These models were employed to evaluate the efficacy of various novel therapeutic modalities including interleukin-3 (IL-3) and low dose aspirin. The efficacy of the latter was found to be interrelated. Low dose aspirin is capable of inhibiting the activity of the enzyme cyclooxygenase which is responsible for the metabolism of arachidonic acid towards the production of prostaglandins. This shifts the metabolism of arachidonic acid to the other pathway and leads to an overproduction of leukotrienes. The leukotrienes act as stimulators of IL-3 production, a positive cytokine in pregnancy which enhances placental and fetal development. In the current study we evaluated the IL-3 levels in pregnant women with APS and expanded our knowledge on the interrelationships between aspirin, arachidonic acid metabolites and IL-3 in the human system. METHODS: IL-3 levels were recorded in the serum of pregnant women with APS and compared to a control pregnant group. In addition peripheral blood mononuclear cells from healthy subjects were incubated with different concentrations of aspirin or with arachidonic acid metabolites (Leukotriene B4, C4 or PGE2), and IL-3 production in the culture fluids was evaluated. RESULTS: Serum level of IL-3 in pregnant patients with primary APS, APS secondary to SLE and SLE was lower in comparison to the control group. The in vitro studies revealed that only low dose aspirin (10 mg/microliters) stimulated IL-3 production while higher doses of the drug failed to induce the cytokine generation. Leukotriene B4 and C4 were stimulatory whereas PGE2 acted as inhibitor of IL-3 production. CONCLUSIONS: The serum level of IL-3 is decreased to pregnant women with primary or secondary APS. Low dose aspirin is capable of stimulating IL-3 production in vitro most probably through an elevation of leukotriene production, which may explain its beneficial activity in preventing the manifestations of APS.

Antiphospholipid Syndrome↗
PubMed1996

Modulation of endothelial cell function by antiphospholipid antibodies.

beta 2-glycoprotein I (beta 2-GP-I) the plasma cofactor for anti-phospholipid antibodies adheres on the endothelial surfaces and can be recognized by anti-beta 2-GP-I antibodies naturally occurring in patients with the anti-phospholipid syndrome. As for the cofactor binding to cardiolipin- or gamma irradiated-plates, the endothelial binding is mediated by the so-called phospholipid binding site, a cationic structure able to react with anionic molecules. Endothelial monolayers appear to represent a substrate able to bind beta 2-GP-I and to present it in a suitable manner in order to allow the binding of anti-beta 2-GP-I beta 2 antibodies. The complex between beta 2-GP-I and the respective antibodies induce an endothelial cell activation as demonstrated by the up-regulation of adhesion molecule expression, the secretion of proinflammatory cytokines and the modulation of arachidonic acid metabolism. Taken together these findings strongly sustain a pivotal role for beta 2-GP-I in allowing antibody deposition on the endothelium and in affecting endothelial cell functions potentially responsible for a procoagulant state.

Antibodies, Antiphospholipid↗
PubMed1995

Transfer of experimental antiphospholipid syndrome by bone marrow cell transplantation. The importance of the T cell.

OBJECTIVE: To investigate the potential of bone marrow cells from mice with primary antiphospholipid syndrome (APS) to transfer the disease to naive mice, and to determine the importance of the role of T cells in the APS. METHODS: Experimental primary APS was induced in naive mice following active immunization with anticardiolipin (aCL) monoclonal antibody (MAb). Whole-population or T cell-depleted bone marrow cells from mice with experimental primary APS were infused into total body-irradiated naive BALB/c recipients. RESULTS: Bone marrow cells (in the presence of T cells) had the potential to induce experimental APS in naive mice, which resulted in high serum titers of aCL, antiphosphatidylserine, and antiphosphatidylinositol antibodies; an increased number of antibody-forming cells specific for each of the above phospholipids; a positive lymph node cell proliferative response to aCL MAb; and clinical features of primary APS, including thrombocytopenia, prolonged activated partial thromboplastin time (indicating the presence of lupus anticoagulant), and a high frequency of fetal resorptions (the equivalent of human fetal loss). T cell-depleted bone marrow cells did not transfer the disease. CONCLUSION: This study demonstrates the important role of T cells in the development and transfer of experimental primary APS and raises the possibility of T cell manipulations in treatments to prevent this condition.

Animals↗