自身抗原在动脉粥样硬化形成中作用的研究进展

动脉粥样硬化（As）是一种由免疫介导的、多因素参与的炎症性疾病。流行病学调查显示,在一些自身免疫性疾病中AS有所加剧,例如系统性红斑狼疮（SLE）和抗磷脂综合征。通过研究认为,几个潜在的自身抗原,如氧化低密度脂蛋白、热休克蛋白65／60和B2糖蛋白I在As的发生和发展中发挥着重要作用。这些新的认识,为人们找到了预防和治疗AS的新靶点。     

Pathogenic roles of anti-beta2-GPI antibody in patients with antiphospholipid syndrome]

Antiphospholipid syndrome (APS) is characterized by arterial and/or venous thrombosis and pregnancy morbidity in the presence of antiphospholipid antibodies (aPL). Beta2-glycoprotein I (beta2-GPI) and prothrombin are representative autoantigens, the former more extensively investigated. Anti-beta2-GPI antibodies are not only markers of APS, but also are considered to be pathogenic. Possible roles of anti-beta2-GPI antibodies are, 1) enhancement the binding of beta2-GPI to anionic phospholipid and inhibition of protein C activation/activated protein C, 2) to form anti-beta2-GPI antibody-beta2-GPI-oxidized LDL complex and to promote uptake by sub-endothelial macrophage, resulting in atherosclerosis, 3) to dimerize beta2-GPI on the surface of platelets and to activate platelets via apoE receptor 2 and subsequent signal transduction, 4) stimulation of monocytes via p38 MAP kinase pathway and induction of tissue factor production. In pregnancy morbidity, activation of complement cascade plays an important role. These findings may provide a novel target in the management of APS.     

Accelerated atherosclerosis, immune response and autoimmune rheumatic diseases

Atherosclerosis (AT) is a chronic autoimmune inflammatory disease, characterized by lipoproteins metabolism alteration leading to formation of pro-inflammatory and pro-oxidative lipids and immune response. Identification of macrophages, T cells, pro-inflammatory cytokines, adhesion cell molecules in atherosclerotic lesions support the hypothesis that innate and adaptive immune response participate in the atherogenesis mechanism. Multiple factors such as inflammatory, infectious and immune system, among others participate in this process. The principal antigens identified in atherogenesis are: oxidized LDL (oxLDL), HSPs and beta2GPI. During LDL oxidation, multiple neoantigens are formed (anti-EO). These antibodies seem to be protective. Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) have accelerated AT. The association of both diseases with AT suggests a common pathogenic mechanism. SLE and atherosclerosis are immune-complex mediated diseases. Participation of complement activation, and CD40, CD40 ligand interactions have been demonstrated in AT and SLE. AT may be the initial presentation or the consequence of primary antiphospholipid syndrome. The similarities between AT, SLE, and APS and the identification of protective antibodies offer opportunities for new immunomodulation treatment strategies.     

Systemic Antiphospholipid Syndrome and Atherosclerosis

Atherosclerosis (AT) is a metabolic, systemic inflammatory/immune disease characterized by lipoproteins metabolism alteration that leads to immune/inflammatory system activation with the consequent proliferation of smooth-muscle cells, narrowing arteries and atheroma formation. Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombophilic state and circulating antiphospholipid antibodies (aPL) including anti β2-GPI. Experimental studies and human observations suggest that APS is associated with AT. In fact, innate and adaptive immune responses participate in the pathogenesis of both diseases. Anti-oxLDL, anti-aPL, anti β2GPI, anti-HSP antibodies, among others, has been found in patients with APS and AT. Endothelial dysfunctions, oxidative stress, increase of cell adhesion molecules, active platelets, are common findings in both diseases. Macrophages, dendritic cells, T-cell activation, CD40–CD40 ligand interaction, are considered as pathogenic mechanism of AT and APS. Premature AT may be the first symptom of APS. Thrombophilia, aPL antibodies, and APS may be present in patients with premature AT. An association between AT and venous thrombosis (a clinical hallmark of APS) has been proposed in unselected patients with deep venous thrombosis of the legs without symptomatic AT. Asymptomatic AT, defined in terms of carotid intima media thickness and lumen diameter decrease, was observed in patients with APS. Premenopausal female patients with PAPS have a higher prevalence of cerebrovascular disease in comparison with male patients. Accelerated AT and hormones could be the explanation of these findings. High levels of aCLs, significantly predict the risk of future ischemic stroke in women but not in men. AT is one of the main features of systemic APS and offer opportunities for new treatment strategies.     

Anti-β 2 -Glycoprotein I Autoantibodies and Atherosclerosis

β-Glycoprotein I (β 2 -GPI) is a major antigen for antiphospholipid antibodies (aPL) present in patients with antiphospholipid syndrome (APS). We previously reported that β 2 -GPI specifically binds to oxidized low-density lipoprotein (oxLDL). Further, a ligand specific for β 2 -GPI, oxLig-1, purified from the extracted lipids of oxLDL was identified as 7-ketocholesterol-9-carboxynonanoate (i.e., 9-oxo-9-(7-ketocholest-5-en-3β-yloxy) nonanoic acid) OxLig-1 was recognized by β 2 -GPI and subsequently by anti-&beta 2 -GPI autoantibodies. Binding of liposomes containing oxLig-1 to macrophages were significantly enhanced in the presence of both β 2 -GPI and an anti-β 2 -GPI autoantibody derived from (NZW×BXSB) F1 mouse, an animal APS model, or from APS patients. Anti-β 2 -GPI autoantibodies derived from APS patients with episodes of arterial thrombosis were detected in ELISA, using a solid phase &beta 2 -GPI complex with oxLig-1. It was also reported that LDL-receptor-deficient mice that were fed a chow diet and immunized with β 2 -GPI had an accelerated atherosclerosis and that β 2 -GPI was abundantly expressed within subendothelial regions and intimal-medial borders of human atherosclerotic plaques. All of these observations strongly suggest that autoimmune atherogenesis linked to β 2 -GPI interaction with oxLDL and autoantibodies may be present in APS.     

Anti-beta 2-glycoprotein I autoantibodies and atherosclerosis

beta 2-Glycoprotein I (beta 2-GPI) is a major antigen for antiphospholipid antibodies (aPL) present in patients with antiphospholipid syndrome (APS). We previously reported that beta 2-GPI specifically binds to oxidized low-density lipoprotein (oxLDL). Further, a ligand specific for beta 2-GPI, oxLig-1, purified from the extracted lipids of oxLDL was identified as 7-ketocholesterol-9-carboxynonanoate (i.e., 9-oxo-9-(7-ketocholest-5-en-3 beta-yloxy) nonanoic acid) OxLig-1 was recognized by beta 2-GPI and subsequently by anti-beta 2-GPI autoantibodies. Binding of liposomes containing oxLig-1 to macrophages were significantly enhanced in the presence of both beta 2-GPI and an anti-beta 2-GPI autoantibody derived from (NZW x BXSB) F1 mouse, an animal APS model, or from APS patients. Anti-beta 2-GPI autoantibodies derived from APS patients with episodes of arterial thrombosis were detected in ELISA, using a solid phase beta 2-GPI complex with oxLig-1. It was also reported that LDL-receptor-deficient mice that were fed a chow diet and immunized with beta 2-GPI had an accelerated atherosclerosis and that beta 2-GPI was abundantly expressed within subendothelial regions and intimal-medial borders of human atherosclerotic plaques. All of these observations strongly suggest that autoimmune atherogenesis linked to beta 2-GPI interaction with oxLDL and autoantibodies may be present in APS.     

Clinical Thrombotic Manifestations in SLE Patients With and Without Antiphospholipid Antibodies: A 5-year Follow-up

Objective To analyze the association of antiphospholipid antibodies (aPL) with the development of clinical thrombotic manifestations and to characterize the efficacy of anti-thrombotic therapies used. Methods 272 systemic lupus erythematosus (SLE) patients participated in the study. Patient files and a cumulative database were used to collect patients’ medical histories. Anti-cardiolipin (aCL), anti-beta2-glycoprotein I (aβ2GPI) antibodies, and lupus anticoagulant (LAC) were measured according to international recommendations. New thrombotic events were registered during follow-up. Results The patients were prospectively studied for 5 years, of whom 107 were aPL negative (aPL− group). Criteria for antiphospholipid syndrome (APS) were fulfilled by 84 of 165 aPL-positive patients (APS+ group) indicating that SLE patients with aPL have around 50% risk to develop thrombotic complications. The aPL+ group (n = 81) consisted of aPL+ but APS− patients. LAC was the most common aPL (n = 27, 32.1%) in patients with APS. The cumulative presence of aPL further increased the prevalence of thrombotic events. During the follow-up period, aPL developed in 8 of 107 patients (7.5%) from the aPL− group, of whom 3 (2.8%) presented with thrombotic complications. Other types of aPL developed in 7 of 165 (4.2%) aPL+ patients within 5 years. New thrombotic events occurred in 3.7% of aPL+ (n = 3) and 8.3% (n = 7) of the APS group. During follow-up, 52 of 81 aPL+ patients received primary prophylaxis, and 1 (1.9%) had transient ischemic attack (TIA). In the non-treatment group, 2 (6.9%) had stroke. Seventy-nine of 84 of the APS patients received secondary prophylaxis, and myocardial infarction occurred in 2 patients (on cumarine therapy maintaining an international normalized ratio around 2.5–3.0), and 5 suffered a stroke/TIA (1 on aspirin and 4 on aspirin + cumarine). Conclusion The findings emphasize the importance of determining both aCL and aβ2GPI antibodies and LAC in SLE patients and the need for adequate anticoagulant therapy.     

Anti-phospholipid antibodies in HIV infection and SLE with or without anti-phospholipid syndrome: comparisons of phospholipid specificity, avidity and reactivity with beta2-GPI.

Increased prevalence of anti-phospholipid antibodies (aPL) and increased levels of lipid peroxidation have been described in patients with HIV infection. To assess the binding specificity and avidity of aPL antibodies in HIV infection, sera from 44 HIV-1 infected patients were evaluated for antibodies to cardiolipin (aCL), phosphatidyl serine (aPS), phosphatidyl inositol (aPI) and phosphatidyl choline (aPC) using enzyme linked immunosorbent assay (ELISA) methods. Sera from 30 patients with systemic lupus erythematosus (SLE), but without features of anti-phospholipid syndrome (APS) (SLE/non APS), six with SLE and secondary APS, (SLE/APS) and 11 with primary APS (PAPS) were also evaluated as controls. The resistance of the aPL antibody binding to dissociating agents was evaluated by treating the ELISA wells, after serum incubation with 2 M urea or 0.6 M NaCl for 10 min. An anti-beta2-glycoprotein-I (beta2-GPI) ELISA was used to assess serum reactivity against beta2-GPI, a plasma protein considered as the true antigen of aCL antibodies occurring in APS and SLE patients. The prevalence of aCL, aPS, aPI and aPC antibodies in HIV-1 infection was 36%, 56%, 34% and 43% respectively, which was comparable to that found in SLE/APS and PAPS patients and significantly higher than that observed in SLE/non-APS patients. Anti-beta2-GPI antibodies occurred in 5% of HIV-1 infected vs. 17% in SLE/non-APS (P=0.11), 50% in SLE/APS (P=0.009) and 70% in PAPS patients (P=0.0014). A significant decrease of aPL binding after urea and NaCl treatment was observed in the sera of HIV-1-infected, compared to that of APS patients, indicating that aPL antibodies from HIV-1 infected individuals have low resistance to dissociating agents. In conclusion, aPL antibodies (1) occur in HIV-1 infection; (2) tend to recognize various phospholipids but not beta2-GPI; and (3) are of low resistance to dissociating agents-a finding probably reflecting low antibody avidity. Finally, these, like the autoimmune-type aCL antibodies, tend to recognize the oxidized CL-a finding probably indicating autoantibody generation as a result of neoepitope formation by oxidized PLs.     

Abstract 11-20

11. Six different APs and b2-GPI in pregnancy with pathology12. Domain 1-specific anti-b2-GPI antibodies from APS patients contribute to lupus anticoagulant activity13. Nodular regenerative hyperplasia (NRH) of the liver – a manifestation of organ-specific antiphospholipid syndrome?14. Practical and beneficial value of comprehensive testing for anti- phospholipid antibodies (aPL)15. Anti-b2-glycoprotein I antibodies as the sole antibodies: about 11 patients16. Frequency and specificities of antiphospholipid antibodies (aPL) in volunteer blood donors17. Interest of dRVVT in antiphospholipid syndrome18. Carboxyl-variants of cholesteryl-linoleate as a ligand for b2- glycoprotein I and a possible mechanism on autoantibody-mediated atherosclerosis19. Antiphospholipid syndrome (APS) presenting as progressive supranuclear palsy (PSP)20. Autoantibodies to cardiolipin and b2-glycoprotein-I in coronary artery disease     

Patients with atherosclerotic syndrome, negative in anti-cardiolipin assays, make IgA autoantibodies that preferentially target domain 4 of beta2-GPI

Autoantibodies targeting beta2-glycoprotein l (beta2-GPI), a component of the atherosclerotic plaque, are commonly found in patients with acute ischemic syndromes. Serum samples from APS (antiphospholipid syndrome) patients and from cardiovascular patients exhibiting acute atherosclerotic syndromes were analyzed for IgG and IgA antibodies in both anti-beta2-GPI and anticardiolipin (aCL) ELISA assays. All of the APS samples used here were positive in both assays. Serum samples from 382 atherosclerosis patients were also analyzed for IgG and IgA antibodies in the same assays. In sharp contrast to the APS samples, we found that only 1% of the samples from atherosclerosis patients were positive for IgA aCL, and 1.6% positive for IgG aCL, whereas 35.6% were positive for IgA anti-beta2-GPI and only 1.6% for IgG anti-beta2-GPI. The antigenic specificity of 29 serum samples from atherosclerosis patients was evaluated. Six different recombinant domain-deleted mutants (DM) of human beta2-GPI and full-length human beta2-GPI (wild-type) were used in competitive inhibition assays to inhibit the autoantibodies from binding in the anti-beta2-GPI ELISA assays. Domain-deleted mutants D--345 and D--45 inhibited the binding in the IgA anti-beta2-GPI assay, suggesting that these autoantibodies recognize domain 4 of the beta2-GPI molecule. These results clearly show that IgA anti-beta2-GPI autoantibodies from atherosclerotic patients are distinct from IgA autoantibodies found in APS samples.     

Detection of antiphospholipid antibodies by automated chemiluminescence assay

The laboratory diagnosis of antiphospholipid antibody syndrome (APS) requires the demonstration of antiphospholipid antibodies (aPL) by lupus anticoagulant (LAC) measured through coagulation assays, anticardiolipin IgG or IgM antibodies (aCL) and/or anti-β2-glycoprotein I IgG or IgM antibodies (anti-β2-GPI), usually detected by ELISA. In this study we tested aCL by a new automated system using the chemiluminescence principle. Our results showed that, while almost all the sera from APS patients, positive for IgG aCL and anti-β2-GPI by ELISA, were also positive for IgG aCl by chemiluminescence, only 30.13% of patients without clinical manifestations of APS, but positive for aCL and persistently negative for anti-β2-GPI (by ELISA) and LA, confirmed the positive test by chemiluminescence. This difference was highly significant (p<0.0001). Interestingly, this test also prompted to identify 20% of patients positive for LA, but persistently negative for both aCL and anti-β2-GPI IgG (ELISA). Thus, the new technology of automated chemiluminescence assay for measuring aPL may represent an useful tool to identify "true" APS patients.     

Oxidized low-density lipoprotein/beta2-glycoprotein I complexes and autoantibodies to oxLig-1/beta2-glycoprotein I in patients with systemic lupus erythematosus and antiphospholipid syndrome

Oxidized low-density lipoprotein (oxLDL) interacts with beta2-glycoprotein I (beta2-GPI) via oxLDL-derived specific ligands (oxLig-1) forming complexes. The prevalence and significance of oxLDL/alpha2-GPI complexes and antibodies to oxLig-1/alpha2-GPI were evaluated in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). The oxLDL/beta2-GPI complex was 69% positive (above mean + 3 SD of control subjects) in 97 consecutive patients with SLE, 62% in 40 patients with SLE with secondary APS, and 60% in 50 control patients with SLE without APS. IgG anti-oxLig-1/beta2-GPI antibody was positive in 31 (32%) of 97 consecutive patients with SLE, in 26 (65%) of 40 patients with SLE with secondary APS, and in 6 (19%) of 32 control patients with SLE. Anti-oxLig-1/beta2-GPI antibodies were 93.7% specific with a positive predictive value of 90.0% for APS, better than anticardiolipin antibodies (80.0% specific, 71.4% predictive value). These results confirm that oxLDL/beta2-GPI complexes are common in SLE and suggest a possible immunogenic role in APS. In contrast, IgG anti-oxLig-1/beta2-GPI antibodies not only are associated with but also are clinically useful risk factors for APS.     

The involvement of beta2-glycoprotein I (beta2-GPI) in human and murine atherosclerosis.

Atherosclerosis is a multifactorial process, the hallmark of which is fat deposition in the vessel wall. Autoimmune factors have recently been shown to play an important role in the initiation and progression of atherosclerosis; candidate autoantigens are oxidized lipids and heat shock proteins. beta2-glycoprotein I (beta2-GPI) is a highly glycosylated plasma protein that serves as a major antigenic target for autoimmune type antiphospholipid antibodies. Its major relevant property is binding to negatively charged phospholipids/surfaces. In the set of studies presented in this paper, we provide evidence pointing towards beta2-GPI as an influential determinant in murine and human atherogenesis. Thus, immunization of transgenic atherosclerosis-prone mice (apolipoprotein E and low-density lipoprotein receptor knockouts) with human beta2-GPI results in a brisk and sustained respective response that extends to cross-react with the 'self' murine beta2-GPI. Atherosclerosis is accelerated in both strains concomitant with the infiltration of CD4 lymphocytes in the aortic sinus of the mice. When human plaques were studied, it was found that beta2-GPI resides in the subendothelial regions and co-localizes with CD4 lymphocytes. Thus, the immune response towards beta2-GPI may play an important role in atherogenesis, serving as a possible target for antigen specific therapies.     

Antiphospholipid antibodies bind ATP: a putative mechanism for the pathogenesis of neuronal dysfunction

Antiphospholipid antibodies (aPL) generated in experimental animals cross-react with ATP. We therefore examined the possibility that aPL IgG from human subjects bind to ATP by affinity column and an enzyme linked immunosorbent assay (ELISA). Sera with high levels of aPL IgG were collected from 12 patients with the antiphospholipid syndrome (APS). IgG fractions from 10 of 12 APS patients contained aPL that could be affinity-bound to an ATP column and completely eluted with NaCl 0.5 M. A significant (> 50%) inhibition of aPL IgG binding by ATP 5 mM was found in the majority. Similar inhibition was obtained with ADP but not with AMP or cAMP. All the affinity purified anti-ATP antibodies also bound beta2-glycoprotein-I (beta2-GPI, also known as apolipoprotein H) suggesting that, similar to most pathogenic aPL, their binding depends on this serum cofactor. We further investigated this possibility and found that the binding of beta2-GPI to the ATP column was similar to that of aPL IgG in that most was reversed by NaCl 0.5 M. Furthermore, addition of beta2-GPI to aPL IgG significantly increased the amount of aPL binding to an ATP column. We conclude that aPL IgG bind ATP, probably through beta32-GPI. This binding could interfere with the normal extracellular function of ATP and similar neurotransmitters.     

Patients with atherosclerotic syndrome,negative in anti-cardiolipin assays,make IgA autoantibodies that preferentially target domain 4 of β2-GPI

Autoantibodies targeting β₂-glycoprotein l (β₂-GPI), a component of the atherosclerotic plaque, are commonly found in patients with acute ischemic syndromes. Serum samples from APS (antiphospholipid syndrome) patients and from cardiovascular patients exhibiting acute atherosclerotic syndromes were analyzed for IgG and IgA antibodies in both anti-β₂-GPI and anticardiolipin (aCL) ELISA assays. All of the APS samples used here were positive in both assays. Serum samples from 382 atherosclerosis patients were also analyzed for IgG and IgA antibodies in the same assays. In sharp contrast to the APS samples, we found that only 1% of the samples from atherosclerosis patients were positive for IgA aCL, and 1.6% positive for IgG aCL, whereas 35.6% were positive for IgA anti-β₂-GPI and only 1.6% for IgG anti-β₂-GPI. The antigenic specificity of 29 serum samples from atherosclerosis patients was evaluated. Six different recombinant domain-deleted mutants (DM) of human β₂-GPI and full-length human β₂-GPI (wild-type) were used in competitive inhibition assays to inhibit the autoantibodies from binding in the anti-β₂-GPI ELISA assays. Domain-deleted mutants D—345 and D---45 inhibited the binding in the IgA anti-β₂-GPI assay, suggesting that these autoantibodies recognize domain 4 of the β₂-GPI molecule. These results clearly show that IgA anti-β₂-GPI autoantibodies from atherosclerotic patients are distinct from IgA autoantibodies found in APS samples.     

Incidental discovery of high systemic lupus erythematosus disease activity associated with cytomegalovirus viral activity

We try to find the association of cytomegalovirus (CMV) infection and anti-β2 glycoprotein 1 autoantibodies (anti-β2 GP1), a key antibody in antiphospholipid syndrome (APS), among systemic lupus erythematosus (SLE) and cerebral vascular accident (CVA) patients. This retrospective study enrolled serum samples obtained from 87 SLE and 97 CVA patients who have been checked for the existence of anti-β2 GP1. First, the prevalence rate of anti-CMV IgG and IgM in patients with and without anti-β2 GP1 were compared. Second, the prevalence of anti-CMV IgG and IgM were compared between SLE and CVA patients. Last, this study analyzed the clinical characteristics and disease activity in SLE patients with positive anti-CMV IgM and IgG. No difference existed in the prevalence rate of anti-CMV IgG and IgM between positive or negative anti-β2 GP1 serum samples in both SLE and CVA patients. However, the prevalence of anti-CMV IgM was significantly higher in the SLE group than in the CVA group. Severity of clinical features and SLEDAI scores were considerably higher in patients with positive anti-CMV IgM than in SLE patients with negative anti-CMV IgM. Very impressively, all IgM-positive SLE samples (9/9) carrying highest levels of anti-CMV IgG, indicated reactivation of the latent CMV infection. Hence, it suggests that CMV reactivation might contribute toward the disease flare in some SLE patients. In future, a prospective and longitudinal study is stongly indicated.     

HLA class II alleles and genetic predisposition to the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by the presence of antiphospholipid antibodies (aPL). Its etiology is linked to genetic predisposition, which is accounted for, at least in part, by genes of major histocompatibility complex (HLA system). The association of APS with human leukocyte antigen (HLA) alleles is a consequence of the association of aPL with HLA alleles. Some HLA alleles carry the risk to produce aPL, and this is independent of the clinical context. In fact, we find the same associations between HLA and aPL in primary APS and in APS secondary to systemic lupus erythematosus (SLE). The association of HLA-DR4, -DR7, -DRw53 and -DQB1*0302 with aCL that has been demonstrated in primary APS can also be found in SLE, a disease with a completely different pattern of HLA allele association (DR2, DR3, DRw52). In addition, the various aPL (anticardiolipin antibodies, lupus anticoagulant, anti-beta2GPI antibodies, antiphosphatidylserine/prothrombin antibodies) show similar HLA association, again independent of the clinical context (primary APS or SLE), and across various ethnic groups.     

Autoantibody-mediated atherosclerosis

Beta2-glycoprotein I (beta2-GPI) is a major antigen for antiphospholipid antibodies (aPL) present in patients with antiphospholipid syndrome (APS). Oxidized low-density lipoprotein (oxLDL) is subsequently targeted by beta2-GPI and anti-beta2-GPI autoantibodies. Ligands specific for beta2-GPI derived from oxLDL have been characterized as oxidized forms of cholesteryl linoleate, such as 7-ketocholesterol-9-carboxynonanoate, i.e. 9-oxo-9-(7-ketocholest-5-en-3beta-yloxy) nonanoic acid, (namely oxLig-1). The in vitro phenomenon that it is significantly increased in binding of oxLig-1 containing liposomes to macrophages via an interaction with beta2-GPI and an anti-beta2-GPI autoantibody (via the Fcgamma receptor) may propose a novel mechanism on 'autoantibody-mediated atherosclerosis'. Furthermore, autoantibodies against a complex of beta2-GPI and oxLig-1 are detected in sera of APS patients and appearance of the antibodies is associated with episodes of thrombosis, especially, arterial thrombosis. Thus, autoimmune atherogenesis linked to beta2-GPI interaction with oxLDL and autoantibodies may be present in APS.     

New developments in viral peptides and APL induction

The associations of antiphospholipid antibodies (aPL) with thrombosis and fetal death are well recognized, but the mechanism(s) that induce their production are not. We demonstrated induction of pathogenic aPL antibodies by immunization with foreign beta(2)-GPI, or synthetic peptides representing the PL-binding site of the beta(2)-GPI. These antibodies caused intrauterine fetal death and transverse myelopathy due to spinal cord infarction in mice, and activated endothelial cells in vitro. We also introduced aPL in mice by immunization with PL-binding viral peptides and observed their pathogenic effects. This study demonstrated that pathogenic effects of aPL antibodies induced by immunization with a human CMV-derived PL-binding synthetic peptide. We hypothesize that in APS patients aPL is induced by beta(2)-GPL-like PL-binding products of human common bacteria or viruses.     

Inhibition of ras by farnesylthiosalicylate significantly reduces the levels of autoantibodies in two animal models of the antiphospholipid syndrome

BACKGROUND: Stimulation and proliferation of lymphocytes require activation of Ras. S-farnesylthiosalicylic acid (FTS) is a synthetic substance that detaches Ras from the inner cell membrane and induces its rapid degradation. Antiphospholipid antibodies (aPL) are a heterogeneous group of antibodies detected in patients with antiphospholipid syndrome (APS), which is associated with thrombosis, pregnancy losses, and thrombocytopenia. OBJECTIVE: To examine the effect of FTS treatment on aPL levels in a genetic autoimmune model (the MRL/lpr mice) and in an induced model of APS. METHODS: Female Balb/C mice immunized once with beta2-glycoprotein I (beta2-GPI) in complete Freund's adjuvant (CFA) and female MRL/lpr mice were treated intraperitoneally with either FTS (5 mg/Kg/day) or saline 3-5 times a week. aPL and anti-beta2-GPI antibodies were measured by ELISA. RESULTS: FTS treatment 3 times a week resulted in significant decreases of aPL and anti-beta2-GPI antibodies in both animal models. In contrast, more frequent treatment (5 times a week) had no significant effect on autantibody levels in both animal models. We further compared 2 protocols in the induced APS model, one for alternate day treatment and the other for daily treatment on the first 3 days each week, and found a decrease in autoantibody levels only in the alternate day protocol. CONCLUSIONS: Inhibition of Ras activation by FTS is effective in decreasing autoantibody levels in models of APS. The differential modulation of immune function by alternate day compared to daily treatment may provide better understanding of the role of Ras activation in this system.