Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02749 (beta2-glycoprotein I)
 836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The laboratory diagnosis of antiphospholipid antibody syndrome currently requires two consecutive positive results in either lupus anticoagulant or anticardiolipin antibody assays. Antibodies against beta-2-glycoprotein I (abeta2-GPI) are suggested as a new marker for the syndrome. The inclusion of abeta2-GPI in the official diagnostic criteria has so far been precluded owing to lack of an international standard and also technical difficulties. Samples from 5367 consecutive patients sent to a national reference laboratory mainly because of various thrombotic events were studied. An IgG abeta2-GPI ELISA assay was performed in addition to lupus anticoagulant (dRVVT and PTT-LA) and IgG anticardiolipin antibody determinations to evaluate patient groups in which the new assay might be of value. From a total of 90 patients, 2.2% of the samples were abeta2-GPI positive; 51 patients had abeta2-GPI as the only positive antiphospholipid antibody marker; 20 patients had had a venous thrombosis and 14 an arterial thrombosis, 4 had pregnancy complications and 2 had thrombocytopenia. Relatively young patients with cerebrovascular ischaemic events seemed especially to present sole abeta2-GPI positivity. The abeta2-GPI positivity remained fairly constant in the 23 patients from whom follow-up samples were taken. It is concluded that the IgG abeta2-GPI assay seems to be a potentially important additional diagnostic tool for the antiphospholipid antibody syndrome.
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PMID:Beta-2-glycoprotein I antibodies in patients with thrombosis. 1275 92

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.
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PMID: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. 1502 48

Beta-2-glycoprotein I (beta(2)GPI) is mainly produced by the liver and is found in plasma partially associated to lipoproteins. Although various properties have been attributed to this protein, its physiological role remains still unclear. We investigated its expression in cultured liver cells and in regenerating liver. Expression studies in HepG2 cells demonstrate that beta(2)GPI mRNA is regulated in a cell cycle-dependent manner, with very low expression in low cycling conditions and increasing levels in proliferating cells. p21 WAF-dependent growth arrest, induced by butyrate treatment, down-regulate beta(2)GPI mRNA levels. Immunolocalization in normal rat liver shows a non-homogeneous pattern, being mainly present in the centrolobular area; post-hepatectomy regenerating rat liver is uniformly immunostained and mitotic elements show the highest protein expression. Albumin gene expression, studies as control liver specific product, was not affected by sodium butyrate induced growth arrest. As previously reported for endothelial cells, beta(2)GPI behaves as survival factor for HepG2 cells: when increasing amounts of the protein (10-50 microg) have been added to serum deficient cultured liver cells a progressive reduced cell loss was observed. In conclusion, the present data demonstrate that beta(2)GPI gene expression is strictly related to the proliferative status of hepatic cells and that this protein could play a role in maintaining liver cells vitality when exposed to different stress factors such as regeneration after partial hepatectomy or growth factors depletion.
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PMID:Beta-2-glycoprotein I is growth regulated and plays a role as survival factor for hepatocytes. 1510 73

The study of IgG and IgM anti-cardiolipin antibodies (IgG/IgM aCL) is now well accepted and is routinely used in the risk assessment of various conditions associated with thrombosis. The aim of the study was to define whether the investigation of aCL is sufficient by itself to evaluate a risk of ischemic stroke. Frequency of aCL and anti-beta2-glycoprotein I (beta2-GPI) antibodies was prospectively investigated in 96 patients with ischemic stroke and in 119 controls by ELISA. In ischemic stroke patients IgG aCL were found in 36%, the IgM-aCL were found in 58%, the IgG-IgM-aCL were found in 43%. The levels of both antibodies were higher in patients with ischemic stroke than in controls (p < 0.01). In controls, IgM-aCL were positive in 2% and IgG-aCL antibodies were negative. IgG-beta-GPI Abs were found in ischemic patients in 19% and IgM-beta2-GPI Abs in 37%. The IgG-IgM-anti-beta2-GPI Abs were found in 24% patients. They were negative in controls. There was a correlation between levels of aCL and anti-beta2-GPI Abs for both isotypes (r = 0.728) but not between IgG- and IgM-beta2-GPI Abs. IgG-aCL test was more sensitive for ischemic stroke than the IgG-beta2-GPI Abs test (71.4%, respectively 65.7%) but less specific (66.8%, respectively 88.6%). The sensitivity of anti-beta2-GPI Abs for ischemic stroke was increased when both isotypes were tested. These results showed that aCL and anti-beta2-GPI Abs could be pathogenetically important for ischemic stroke and that anti-beta2-GPI Abs testing might contribute to a better evaluation of ischemic stroke.
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PMID:Study of anti-cardiolipin and anti-beta2-glycoprotein I antibodies in patients with ischemic stroke. 1552 3

The aim of this study was to evaluate the heterogeneity of IgGanti-beta2-glycoprotein I antibodies (IgG-abeta2GPI) as regarding their reactivity pattern against different sources of human beta2 GPI, their avidity and their association with clinical events of antiphospholipid syndrome (APS). Three thousand six hundred and eighty-four consecutive patient sera were routinely tested for IgGabeta2 GPI over 1 year using an in-house ELISA with 2 different commercial preparations of human purified beta2GPI. Of the 340 sera found positive, all those clinically documented were included in this study; 61 were positive with only one preparation (S1) and 59 with both (S2). The results of ELISA were confirmed by Western blot. Heterogeneity was stressed by testing sera with a human recombinant protein and 3 beta2GPI-related peptides. No contribution of glycosylation in the binding to beta2GPI was found. The avidity indices for each protein were significantly higher in S1 than in S2 (p=0.0021). S2 were more associated with antiphospholipid antibodies than S1 (75% versus 21% ; p<0.0001). A similar frequency of the main clinical features of APS was found in S1 and S2 sera (69% and 71%, respectively). In conclusion, our data show a heterogeneity in the antigenic reactivity pattern of IgG- abeta2 GPI and a relationship between a binding profile and antibody avidity. This heterogeneity could represent a crucial factor of variability in test results and underlines the difficulty of getting standardisation.
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PMID:Heterogeneity of anti-beta2-glycoprotein I antibodies. A factor of variability in test results. 1563 Apr 95

Annexins (Anx) are a family of structurally related proteins that all bind to anionic phospholipids in a Ca(2+)-dependent manner. Some biological properties of beta-2-glycoprotein I (beta(2)-GPI) are similar to those of Anx IV and Anx V. Urinary trypsin inhibitor (UTI) helps to maintain normal pregnancy and prevent preterm delivery by inhibiting uterine contraction. However, plasma beta(2)-GPI and UTI levels have not been measured in normal pregnancy. The aim of this study is to clarify the levels of these parameters. Subjects were nonpregnant women (n=50), 120 pregnant women, and maternal subjects just after delivery (n=53) or postpartum (n=67). All of the subjects were healthy. Plasma levels of beta(2)-GPI, UTI, Anx IV, Anx V and other coagulation and fibrinolysis markers were measured by ELISA. The mean plasma level of beta(2)-GPI was significantly increased during the third trimester of pregnancy and 3 to 5 days after delivery. The mean plasma level of UTI was unchanged from the first trimester of pregnancy to the postpartum period. The mean plasma UTI level in vaginal delivery group was significantly higher than that in cesarean section group. beta(2)-GPI protein was expressed in some of the syncytiotrophoblasts. These data suggest that beta(2)-GPI might act to prevent blood clotting on the placental surfaces and also prevents disseminated intravascular coagulation in the microcirculation and maternal plasma. UTI levels might be kept constant by increased urinary excretion despite overproduction during pregnancy.
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PMID:Beta-2-glycoprotein I and urinary trypsin inhibitor levels in the plasma of pregnant and postpartum women. 1591 97

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.
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PMID:Antiphospholipid antibodies bind ATP: a putative mechanism for the pathogenesis of neuronal dysfunction. 1629 22

The presence of lupus anticoagulant (LA) predisposes to fetal loss and to venous and arterial thrombosis; however, a subgroup of women is unaffected by pregnancy loss. Currently, no predictive markers are available for the identification of women positive for LA at increased risk for pregnancy loss. It was the aim of our study to investigate whether increased anti-beta2-GPI-antibodies predict pregnancy loss in women positive for LA. We performed a cross-sectional study in a cohort of 39 women with persistent LA, who had in total 111 pregnancies. Fifteen women had exclusively normal pregnancies (30 pregnancies) and 24 women had pregnancy losses (81 pregnancies). Anti-beta2-GPI-antibodies were determined using a semiquantitative enzyme linked immunoassay (QUANTA Lite beta2 GPI IgG and IgM; Inova Diagnostics). Increased levels of anti-beta2-GPI antibodies were significantly associated with pregnancy loss [odds ratio (OR) 9.6, 95% confidence interval (CI) 1.6-56.4]. This risk was even higher in the subgroup of women (n = 16) with more than two miscarriages or fetal loss after the first trimester [OR 13.1, 95% CI 1.4-126.3]. There was no significant association between anticardiolipin antibodies and pregnancy loss [OR 3.5, 95% CI 0.7-17.6]. The co-existence of anti-beta2-GPI and anticardiolipin antibodies was also predictive for pregnancy loss [OR 6.1, 95% CI 1.3-29.7]. Interestingly, the prevalence of thrombosis was similar between women with normal pregnancy (87%) and those with pregnancy loss (75%). We conclude that increased levels of anti-beta2-GPI antibodies are predictive for pregnancy loss among women positive for LA, and that prophylactic treatment should be considered in these women even without a history of previous pregnancy loss.
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PMID:Anti-beta2-glycoprotein I antibodies are associated with pregnancy loss in women with the lupus anticoagulant. 1667 70

We clarified the clinical significance of IgG anti-phosphatidylserine-prothrombin complex (PS-PT) antibodies in the antiphospholipid syndrome (APS). The study population consisted of 122 patients with SLE and lupus-like disease. IgG anti-PS-PT antibodies were detected in 44% of 59 patients according to the diagnostic criteria by Harris and Hughes. This frequency was significantly (p < 0.005) higher than the 14% seen in patients without APS. IgG anti-PS-PT antibodies were strongly (p < 0.005) associated with thrombosis. In addition, IgG anti-PS-PT antibodies were positive in 64% of IgG beta2-GPI dependent anti-cardiolipin antibody negative APS patients under the Sapporo criteria. The above findings indicate that IgG anti-PS-PT antibodies as well as beta2,-GPI dependent anti-cardiolipin antibodies should be examined in the diagnosis of APS.
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PMID:[Clinical significance of anti-phosphatidylserine-prothrombin complex antibodies in antiphospholipid syndrome]. 1670 13

Oxidized low-density lipoprotein (oxLDL) is thought to promote atherosclerosis through complex inflammatory and immunologic mechanisms that lead to lipid dysregulation and foam cell formation. Recent findings suggested that oxLDL forms complexes with beta2-glycoprotein I (beta2GPI) and/or C-reactive protein (CRP) in the intima of atherosclerotic lesions. Autoantibodies against oxLDL/beta2GPI complexes occur in patients with systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS) and significantly correlate with arterial thrombosis. IgG autoantibodies having similar specificity emerged spontaneously in non-immunized NZWxBXSB F1 mice, an animal model of APS, and a monoclonal autoantibody (WB-CAL-1; IgG2a) against complexed beta2GPI (oxLDL/beta2GPI complexes) was derived from the same mice. WB-CAL-1 significantly increased the in vitro uptake of oxLDL/beta(2)GPI complexes by macrophages. This observation strongly suggests that such IgG autoantibodies are pro-atherogenic. In contrast, IgM anti-oxLDL natural antibodies found in the atherosclerosis-prone mice (ApoE(-/-) and LDL-R(-/-) mice) have been proposed to be anti-atherogenic (protective). The presence of IgG anti-oxLDL antibodies in humans has been documented in many publications but their exact clinical significance remains unclear. In this article, we review recent progress in our understanding of the mechanisms involved in oxidation of LDL, formation of oxLDL complexes, and antibody mediated-immune regulation of atherogenesis.
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PMID:Oxidative modification of low-density lipoprotein and immune regulation of atherosclerosis. 1679 Feb 79


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