Placental pathology in systemic lupus erythematosus with antiphospholipid antibodies

Systemic lupus erythematosus (SLE) is associated with a poor pregnancy outcome. Antiphospholipid antibodies (APL), which include lupus anticoagulant (LAC) and anticardiolipin antibodies (aCL), are frequently found in patients with SLE, and their presence has been associated with fetal loss. To examine placental pathologic features of SLE patients with APL, we performed a pathologic study on 47 placental tissue samples from 47 pregnant SLE patients with APL (15 patients; four LAC single-positive patients, seven aCL single-positive patients, four LAC and aCL double-positive patients) and without APL (32 LAC and aCL double-negative patients). The incidence of extensive infarction, decidual vasculopathy, decidual thrombosis and perivillous fibrinoid change, which have been thought to be characteristic lesions of APL placenta, was significantly higher in the LAC and aCL double-positive patients than in the patients without APL. Conversely, the above-mentioned lesions between the LAC or aCL single-positive patients and the APL negative patients did not differ significantly. Among the 15 patients with APL, two of the three patients with both decidual vasculopathy and thrombosis had extensive infarction associated with fetal death. Moreover, the patients having fetal death showed LAC and aCL double-positivity. In conclusion, this study indicated that the LAC and aCL double-positivity is an important factor for extensive infarction resulting from decidual vasculopathy and decidual thrombosis in the SLE placenta. Moreover, it was indicated that LAC and aCL double-positivity is an important risk factor for fetal death in the SLE patient.     

Fine specificities of anti-nuclear antibodies in murine models of graft-versus-host disease.

Two models of murine graft-versus-host disease (GVHD) were studied with respect to autoantibody production and development of systemic lupus erythematosus (SLE) like disease. One model was induced by injection of (B10.A(4R) x B10.A(2R]F1 mice with parental (B10.A(4R] spleen and lymph node cells (groups I GVHD), the other by injection of (DBA/2 x C57/B16)F1 mice with DBA/2 cells (group II GVHD). Group I GVHD mice remained in a seemingly healthy condition and did not show any proteinuria, in spite of high titres of anti-nuclear antibodies including antibodies to dsDNA, anti-Sm and anti-ribosomal P protein antibodies. Measured levels of these autoantibodies as well as their isotypes were comparable with those found in MRL/lpr and NZB/W mice. Group II GVHD mice developed SLE-like disease signs, including severe proteinuria. At 4 months after induction of the GVHD, almost 50% of these mice had died. At the time nephritis was present, group II mice also produced anti-dsDNA and anti-nuclear antibodies of other (unknown) specificities, but no anti-Sm or anti-P. Furthermore, the incidence of these antibodies was lower than observed in group I GVHD, MRL/lpr or NZB/W mice. It is concluded that (high avidity) anti-dsDNA as well as anti-Sm and anti-P may be present in the circulation without giving rise to the development of nephritis.     

抗核小体抗体与儿童系统型红斑狼疮的相关性

目的探讨抗核小体抗体（AnuA）在诊断儿童系统型红斑狼疮（SLE）中的敏感性和特异性，了解AnuA与儿童SLE临床特征、疾病活动性的相关性。方法用Hep-2细胞提取核小体。用酶联免疫吸附方法（ELISA）测定血清中的AnuA，分析AnuA和临床表现的相关性。结果52例SLE中18例AnuA阳性。27例疾病对照组中1例AnuA阳性，30例正常对照组AnuA均为阴性。AnuA在儿童SLE中的敏感性为35％，特异性为96％。AnuA阳性组SLE患儿100％有中枢神经系统损害，AnuA阴性组为47％（x^2=14．57，P〈0．05）。AnuA阳性组SLE患儿100％有肾脏损害，AnuA阴性组为5l％（x^2=13．31，P〈0．05）。AnuA阳性和AnuA阴性的SLE患儿SLEDAI评分高于10分者分别为100％和71％（x^2=6．56，P〈0．05）。结论AnuA对儿童SLE的诊断具有较高的特异性，有助于抗dsDNA抗体、抗心磷脂抗体阴性的儿童SLE的诊断。     

Characterization of anti-endothelial cell antibodies in systemic lupus erythematosus (SLE).

IgG anti-endothelial antibodies (AEA), as measured by ELISA or immunoblotting technique could be detected in serum samples of 56 out of 64 patients with SLE (88%) and mainly occurred in monomeric form. AEA were not cell specific, because the binding reactivity was absorbed partially by both fibroblasts and peripheral blood mononuclear cells. No correlation was found between the presence of AEA and anti-nuclear antibodies. Immunoblotting revealed reactivity of AEA against endothelial antigens ranging in size from 15 to 200 kD. AEA titres were significantly higher in patients with joint or skin abnormalities, compared with patients without these abnormalities. A significant correlation was found between nephritis in SLE and the presence of AEA reactivity against endothelial membrane antigens of 38, 41 and 150 kD. These data show that the pattern of AEA reactivity in serum of SLE patients is heterogeneous, and suggest that AEA against a limited number of antigens may be involved in the pathogenesis of nephritis in SLE.     

Spectrophotometric assay for the detection of antibodies to DNA

A spectrophotometric assay for the detection of anti-DNA antibodies in the sera of patients with various connective tissue diseases is described. The sensitivity of the method was compared with hemagglutination and enzyme-linked immunosorbent assay. The method is convenient, specific and suitable for use in clinical laboratories where facilities for radioimmunoassay do not exist.     

Heterogeneity of binding reactivity to different phospholipids of antibodies from patients with systemic lupus erythematosus (SLE) and with syphilis.

The binding specificities were investigated of anti-phospholipid antibodies derived from sera from 55 patients with SLE and related diseases, and from 33 patients with syphilis. Antibodies from both these groups of patients bind strongly to cardiolipin in solid-phase immunoassays, but only antiphospholipid antibodies from patients with autoimmune diseases are associated with thrombotic complications and recurrent spontaneous abortions. IgG anti-phospholipid antibodies from both groups of patients cross-reacted with a range of negatively charged phospholipids, but binding to neutral phospholipids was largely restricted to sera from patients with syphilis. A monoclonal IgM lambda anti-cardiolipin antibody, derived from a patient with autoimmunity, was used to inhibit binding of anti-phospholipid antibodies to cardiolipin and to phosphatidic acid. This antibody inhibited the binding of autoimmune sera to cardiolipin more strongly than sera from syphilis patients, but the converse pattern of inhibition of binding to phosphatidic acid was observed. The VDRL titre correlated with anti-phospholipid antibody activity in sera from syphilis patients, but not from those with autoimmunity. Lupus anti-coagulant activity correlated weakly with IgG antibody levels to each of the negatively charged phospholipids among the patients with autoimmunity. Lupus anticoagulant activity did not correlate uniquely with any anti-phospholipid antibody specificity. These results provide further documentation of the great heterogeneity of anti-phospholipid antibodies associated with autoimmune disease and syphilis.     

Lupus anti-DNA antibodies bearing the 8.12 idiotype appear to be somatically mutated

Anti-DNA antibodies in systemic lupus erythematosus (SLE) sera were analyzed using an antiidiotype designated 8.12 which recognizes a determinant on lambda light chains highly expressed in SLE sera. Eight of ten normal individuals had peripheral blood lymphocytes which produced high-titered 8.12-positive antibodies, following transformation with Epstein Barr virus, implying that the 8.12-reactive sequence originates in the germline gene (GLG). Of 58 SLE sera, 32 contained elevated titers of 8.12-reactive antibodies. Twenty-three of these sera had 8.12-reactive anti-DNA antibodies, suggesting a strong correlation between 8.12 idiotype and DNA binding. Moreover, 20 of 26 8.12-reactive IgG antibodies and only 4 of 10 8.12-reactive IgM antibodies bound DNA (P<0.05). These observations strengthen our previous findings in myeloma sera that DNA binding is associated with IgG isotype in the 8.12 idiotype system and suggest that the acquisition of anti-DNA reactivity in antibodies bearing the GLG idiotype 8.12 is achieved by somatic mutation, a feature of an antigen-driven response.     

Antineutrophil cytoplasmic antibodies and other immunologic abnormalities in patients with habitual abortion.

PROBLEM: The immunologic mechanisms of pregnancy loss in habitual aborters with antiphospholipid and antinuclear antibodies have not been fully clarified. The possible association of antineutrophil cytoplasmic antibodies (ANCAs) with recurrent miscarriage was examined. METHOD OF STUDY: In a prospective, controlled trial of 59 women with recurrent abortion, the prevalence of pANCA (antimyeloperoxidase), cANCA (antiproteinase-3), and immunoserologic abnormalities of systemic lupus erythematosus (SLE) anti double-stranded DNA, anti-SSA, anti-SSB, anti-U1RNP, anti-Sm, anticardiolipin and antinuclear antibodies, LE-cell, lupus anticoagulant, and complement-3 were investigated. RESULTS: pANCA occurred in 2, and cANCA in 6 of 59 case patients, but neither was observed in the controls (P = 0.09 for cANCA). cANCA levels were significantly higher in patients than in controls (P = 0.028). Six recurrent aborters were identified as having a group of immunoserologic abnormalities characteristic of SLE. CONCLUSIONS: Immunologic mechanisms detectable in SLE may operate in a subgroup of habitual aborters with suspected immunologic cause. ANCAs occur more frequently in patients with recurrent miscarriage than in controls.     

Anti-ribosomal antibodies bind the Sm proteins D and B/B′

In order to analyse the specificity of human anti-ribosomal P protein antibodies, anti-ribosomal P protein antibodies were affinity-purified from the sera of lupus patients. Their binding capacity towards recombinant SmD protein and recombinant SmB/B′ protein was evaluated by immunoblot and ELISA. Epitope mapping of SmD was performed by means of synthetic peptides. Anti-ribosomal P protein antibodies bound recombinant SmD (5/10) and SmB/B′ (4/10) on immunoblot; 6/10 showed binding capacity to SmD on ELISA. Inhibition experiments using ELISA confirmed the specificity of this binding. Our data indicate the cross-reactivity of spontaneously developed anti-ribosomal P protein antibodies with the B/B′ and D constituents of the Sm complex. The coexistence of anti-Sm and anti-ribosomal antibodies in lupus sera may therefore be due, at least in part, to the reactivity of a single autoantibody population.     

Detection of anti-RNA antibodies in systemic lupus erythematosus by ELISA using nylon as solid support

A highly sensitive and reproducible enzyme-linked immunosorbent assay (ELISA) for the detection of anti-RNA antibodies is described. The assay procedure involves adsorption of total cellular RNA on nylon beads which could be conveniently stored for a considerable period of time without loss in antigenicity. Sixty-four percent of systemic lupus erythematosus (SLE) sera were positive for anti-RNA antibodies with fluorogenic substrate against 48% with colorigenic substrate.     

Human anti-fibronectin antibodies in systemic lupus erythematosus: occurrence and antigenic specificity.

Sera from patients with connective tissue diseases exhibit autoantibodies to a spectrum of extracellular matrix proteins. Antibodies binding to solid phase bovine fibronectin (Fn) were investigated by ELISA in patients with systemic lupus erythematosus (SLE). Sera showing binding of 2 s.d. above the mean of the normal human control were considered positive and 43/150 SLE sera (28.7%) demonstrated such binding. These antibodies were mainly IgG and IgA as determined by isotype-specific ELISA. Specificity studies on selected positive sera revealed that binding was inhibited by preincubation with soluble Fn, but not with thyroglobulin or type 1 collagen. The binding was demonstrated not to be related to interactions with rheumatoid factor, complement components or immune complexes. Additional studies to determine which Fn fragment is bound by naturally occurring anti-Fn antibodies demonstrated that the binding was predominantly to the 30-kD collagen binding domain (CBD) of Fn molecule. Inhibition studies using 120-kD, 40-kD and 30-kD Fn fragments confirmed that this binding site was the 30-kD CBD.     

狼疮肾炎小鼠肾脏的比较蛋白质组学研究

目的探讨狼疮肾炎(LN)小鼠肾脏和正常小鼠肾脏蛋白质组的差异。方法应用双向凝胶电泳技术(two-dimensional gel electrophoresis,2-DE)分离肾组织总蛋白质,凝胶用银染显色,扫描仪获取凝胶图像并对其进行软件分析。结果同组实验重复3次,其中正常对照组3张图找到蛋白质点平均573±52个,匹配率为83%;LN组找到蛋白质点平均658±43个,匹配率为87%。经软件分析,LN组和对照组比较表达增加大于2倍的点有119个;降低大于0.5倍的点有140个。结论LN小鼠肾脏蛋白质表达发生了显著变化,这可能和LN的发生发展有着密切关系。     

Anti-endothelial cell antibodies in systemic vasculitis and systemic lupus erythematosus (SLE): effects of heat inactivation on binding and specificity

Heating sera is used to inactivate complement but may affect the binding characteristics of autoantibodies. We studied the effect of heating sera from patients with systemic vasculitides and SLE on antibody binding to cultured human umbilical vein endothelial cells. Sera from 32 patients with systemic vasculitides, eight with SLE and 10 healthy controls were studied for anti-endothelial cell antibodies (AECA) using an ELISA before and after heating sera to 56 degrees C for 30 min. The median (range) AECA binding index in the patient group increased from 20% (0-153%) to 71.5% (10-259%) (P < 0.0001). The AECA binding index in the control group also increased from 14% (0-52%) to 90% (42-154%) (P < 0.0001). The increased binding was unaffected by the addition of fresh complement or removal of immune complexes and the increased binding after heating persisted even after cooling to 4 degrees C. Specificity experiments showed that after heating, the binding specificity of sera was lost. Removal of immunoglobulin with Protein A abolished the increased binding seen after heating. Heating sera increases AECA binding in both patient and control sera. The mechanism is probably non-specific damage to the immunoglobulin molecule, and heating sera should thus be avoided.     

Specificity and immunochemical properties of antibodies to bacterial DNA in sera of normal human subjects and patients with systemic lupus erythematosus (SLE)

To elucidate the mechanisms of anti-DNA production, we assessed the binding of sera of normal human subjects (NHS) and patients with SLE to a panel of bacterial and mammalian DNA. Using single-stranded DNA as antigens in an ELISA, NHS showed significant binding to some but not all bacterial DNA, while lacking reactivity to calf thymus DNA. Among bacterial DNA, the highest levels of binding were observed with DNA from Micrococcus lysodeikticus and Staphylococcus aureus. In contrast, SLE sera showed high levels of binding to all DNA tested. To evaluate further immunochemical properties of the anti-DNA antibodies, the subclass distribution of these responses was evaluated by subclass-specific reagents. While NHS showed a predominance of IgG2 antibodies to bacterial DNA, SLE sera had a predominance of IgG1 antibodies to these antigens. Together, these results provide further evidence for the antigenicity of bacterial DNA and suggest that NHS and SLE anti-DNA differ in the patterns of epitope recognition as well as mechanisms of induction.     

Adsorption of anti-dsDNA antibodies by immobilized polyanionic compounds.

Antibodies to dsDNA are characteristically present in serum from patients with systemic lupus erythematosus (SLE), and have been shown to have the capacity to react with various molecules bearing repeating negative charges. After a number of polymeric or monomeric molecules with differently charged groups and hydrophobic molecules had been coupled covalently as ligands on cellulose gel, the adsorption capacities of the ligands for anti-dsDNA antibodies were evaluated. It was found that gels coupled with polyanionic dextran sulphate (DXS) and polyacrylic acid (PA) and monoanionic sulphanilic acid (SA) absorbed anti-dsDNA antibodies effectively. DXS gel also adsorbed antibodies to ssDNA and heparan sulphate, antigens with repeating negatively charged moieties, while no ligand was able to adsorb anti-nRNP antibodies. The finding that DXS gels adsorbed anti-dsDNA antibody in proportion to their charge density, and that the interaction between anti-dsDNA and DXS gel is broken readily by an increase in ionic strength, indicated that the binding is ionic in nature. Moreover, virtually all F(ab')2 anti-dsDNA became adsorbed onto the DXS gels, suggesting that the binding occurred via specific antigen-binding sites on the antibody molecule. Binding of these polyanion-binding autoantibodies with anionic sites in the glomerular basement membrane may therefore cause the tissue damage observed in SLE.     

Relationship between natural and infection‐induced antibodies in systemic autoimmune diseases (SAD): SLE,SSc and RA

Infection or vaccine‐induced T cell‐dependent immune response and the subsequent high‐affinity neutralizing antibody production have been extensively studied, while the connection between natural autoantibodies (nAAbs) and disease‐specific antibodies has not been thoroughly investigated. Our goal was to find the relationship between immunoglobulin (Ig)M and IgG isotype nAAbs and infection or vaccine‐induced and disease‐related autoantibody levels in systemic autoimmune diseases (SAD). A previously described indirect enzyme‐linked immunosorbent assay (ELISA) test was used for detection of IgM/IgG nAAbs against citrate synthase (anti‐CS) and F4 fragment (anti‐F4) of DNA topoisomerase I in 374 SAD samples, with a special focus on systemic lupus erythematosus (SLE) (n = 92), rheumatoid arthritis (n = 73) and systemic sclerosis (n = 157) disease groups. Anti‐measles IgG and anti‐dsDNA IgG/IgM autoantibodies were measured using commercial and in‐house indirect ELISA tests. In all SAD groups the anti‐measles IgG‐seropositive cases showed significantly higher anti‐CS IgG titers (P = 0·011). In anti‐dsDNA IgG‐positive SLE patients, we detected significantly higher levels of anti‐CS and anti‐F4 IgG nAAbs (P = 0·001 and < 0·001, respectively). Additionally, we found increased levels of IgM isotypes of anti‐CS and anti‐F4 nAAbs in anti‐dsDNA IgM‐positive SLE patients (P = 0·002 and 0·016, respectively). The association between IgG isotypes of pathogen‐ or autoimmune disease‐related antibodies and the IgG nAAbs may underscore the immune response‐inducible nature of the diseases investigated. The relationship between protective anti‐dsDNA IgM and the IgM isotype of anti‐F4 and anti‐CS may provide immunoserological evidence for the beneficial roles of nAAbs in SLE patients.     

Inhibition of histone/anti-histone reactivity by histone-binding serum components; differential effect on anti-H1 versus anti-H2B antibodies.

IgG fractions were purified on a protein G-agarose column from sera of both systemic lupus erythematosus (SLE) patients and healthy donors. All IgG fractions, after elution with 0.5 M acetic acid, reacted with histones in an anti-histone ELISA assay, and IgG anti-histone activity was in all instances higher in the IgG fraction than in the corresponding whole serum. This was shown to be due to the presence in serum of histone-binding components that inhibited IgG binding to histones. Both normal human and SLE patients' sera had these histone-binding components, and disparity between serum-positive and -negative anti-histone antibody (AHA) tests was not dependent on differences in the blocking capacity but on IgG antibody levels and avidity. Interaction of normal serum IgG fraction with all five histones was of low avidity, whereas interaction of IgG from AHA-positive SLE sera with both H1 and H2B had high avidity. Low-affinity antibodies to every histone fraction, but also high-affinity anti-H1 antibodies, were preferentially inhibited. Our data indicate that several serum protein components are inhibiting histone/anti-histone interaction and may play a protective role against both high-affinity anti-H1 antibodies present in SLE patients, and natural, low-affinity, anti-histone antibodies. As some acute phase proteins, notably C-reactive protein, bind to histones, it is conceivable that they play such a role. High-affinity anti-H2B antibodies, present in some SLE patients, and not inhibited by these serum components, may, on the other hand, participate in the pathogenesis of the disease.     

Peripheral blood serum from healthy donors contains antibodies against the fragment of transcribed region of ribosomal repeat

Enzyme immunoassay showed that blood serum from healthy donors contains specific high-affinity antibodies (apparent association constant ≥5×10⁹ M^–1) against a fragment of transcribed region of ribosomal DNA repeat of human serum, which are present in a free form or are bound to extracellular DNA. Preheating of the serum at 55°C and high ionic strength (1.5 M NaCl) had no effect on the interaction of antibodies with this fragment. Competitive binding assay showed that these antibodies recognize DNA epitopes, which differ from the epitopes recognized by most anti-DNA antibodies in systemic lupus erythematosus. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 9, pp. 277–281, September, 2007     

IgM anti-myeloperoxidase antibody-secreting lymphocytes are present in the peripheral repertoire of lupus mice but rarely differentiate into IgG-producing cells.

Two IgM, kappa anti-myeloperoxidase (MPO) monoclonal antibodies, 6D6 and 9B5, bound to MPO in a solid-phase enzyme-linked immunosorbent assay were derived from the splenocytes of (NZB x NZW) F1 and MRL/lpr-lpr mice, respectively. 6D6 gave a characteristic perinuclear immunofluorescence staining pattern on ethanol-fixed human neutrophils, bound to the native form of MPO by immunoblotting and had a high constant affinity for MPO as demonstrated by real-time specific interaction. 9B5 produced a cytoplasmic immunofluorescence staining pattern, reacted with the heavy chain of MPO and had a low constant affinity for MPO. The heavy-and light-chain variable region genes of monoclonal antibodies (mAb) 6D6 and 9B5 were sequenced and found to be highly homologous to germline genes and to contain negatively charged amino acids in the complementarity determining regions. IgM MPO-binding activity was observed in most BW and MRL/lpr-lpr mouse sera, which may correspond to polyclonal activation of B cells, whereas IgG anti-MPO antibodies could be rarely detected. Thus, this study indicates that (i) BW and MRL/lpr-lpr mice do not delete IgM anti-MPO secreting B cells, do not maintain these B cells in a state of anergy, but most individuals are not able to spontaneously induce the class-switching of this autoantibody population; (ii) IgM anti-MPO antibodies can recognize different epitopes on MPO and produce different immunofluorescence staining pattern on ethanol-fixed human neutrophils, as demonstrated by the immunochemical properties of the two lupus-mouse derived mAb.     

Decreased levels of autoantibodies against apolipoprotein B‐100 antigens are associated with cardiovascular disease in systemic lupus erythematosus

Increased production of autoantibodies is a characteristic feature of systemic lupus erythematosus (SLE) and there is evidence that several of these autoantibodies may contribute to increased cardiovascular disease (CVD) in SLE. Autoantibodies against the apolipoprotein (apo) B‐100 peptides p45 and p210 have been associated with a lower CVD risk in non‐SLE cohorts. The aim of the present study was to investigate how SLE affects the occurrence of these potentially protective autoantibodies. The study cohort consisted of 434 SLE patients and 322 age‐ and sex‐matched population controls. Antibodies against native and malondialdehyde (MDA)‐modified p45 and p210 were measured by enzyme‐linked immunosorbent assay (ELISA). SLE patients had significantly lower levels of p210 immunoglobulin (Ig)G and p45 IgM (both the native and malondialdehyde (MDA)‐modified forms). SLE patients with manifest CVD (myocardial infarction, ischaemic cerebrovascular disease or peripheral vascular disease) had lower levels p210 IgG and p45 IgM than SLE patients without CVD. Decreased levels of these autoantibodies were also observed in SLE patients with permanent organ damage, as assessed by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (ACR) Damage Index (SDI). The present findings show that patients with SLE, a condition generally characterized by abundance of autoantibodies of multiple specificities, have reduced levels of antibodies against the apo B‐100 antigens p45 and p210 and that the levels of these antibodies are reduced further in SLE patients with CVD. These observations suggest the possibility that an impaired antibody‐mediated removal of damaged LDL particles may contribute to the development of vascular complications and organ damage in SLE.