Antibodies to age‐β2glycoprotein I in patients with anti‐phospholipid antibody syndrome

Anti‐phospholipid antibody syndrome (APS) is a systemic autoimmune disease characterized clinically by arterial and/or venous thromboses, recurrent abortions or fetal loss and serologically by the presence of ‘anti‐phospholipid antibodies’ (aPL). The main target antigen of the antibodies is β₂glycoprotein I (β₂GPI). Post‐translational oxidative modifications of the protein have been widely described. In this study we aimed to analyse sera reactivity to glucose‐modified β₂GPI (G‐β₂GPI). Sera collected from 43 patients with APS [15 primary APS (PAPS) and 28 APS associated with systemic lupus erythematosus (SLE) (SAPS)], 30 with SLE, 30 with rheumatoid arthritis (RA) and 40 healthy subjects were analysed by an enzyme‐linked immunosorbent assay (ELISA) using a G‐β₂GPI. Nine of 15 consecutive PAPS out‐patients (60%) and 16 of 28 SAPS (57.1%) showed serum antibodies [immunoglobulin (Ig)G class] against G‐β₂GPI (anti‐G‐β₂GPI) by ELISA. The occurrence of anti‐G‐β₂GPI was significantly higher in APS patients compared to patients suffering from SLE. No RA patients or control healthy subjects resulted positive for anti‐G‐β₂GPI. Of note, aG‐β₂GPI prompted to identify some APS patients (four PAPS and seven SAPS), who were negative in the classical anti‐β₂GPI test. Moreover, in APS patients, anti‐G‐β₂GPI titre was associated significantly with venous thrombosis and seizure in APS patients. This study demonstrates that G‐β₂GPI is a target antigen of humoral immune response in patients with APS, suggesting that β₂GPI glycation products may contain additional epitopes for anti‐β₂GPI reactivity. Searching for these antibodies may be useful for evaluating the risk of clinical manifestations.     

Immunoglobulin A anti‐phospholipid antibodies in Swedish cases of systemic lupus erythematosus: associations with disease phenotypes,vascular events and damage accrual

Immunoglobulin (Ig) G‐ and IgM‐class anti‐cardiolipin antibodies (aCL) and lupus anti‐coagulant (LA) are included in the 1997 update of the American College of Rheumatology (ACR‐97) systemic lupus erythematosus (SLE) criteria. Despite limited evidence, IgA‐aCL and IgA anti‐β₂‐glycoprotein‐I (anti‐β₂GPI) were included in the 2012 Systemic Lupus International Collaborating Clinics criteria. The present study aimed to evaluate IgG‐/IgA‐/IgM‐aCL and anti‐β₂GPI occurrence in relation to disease phenotype, smoking habits, pharmacotherapy, anti‐phospholipid syndrome (APS) and organ damage among 526 Swedish SLE patients meeting ACR‐97. Patients with rheumatoid arthritis (n = 100), primary Sjögren’s syndrome (n = 50) and blood donors (n = 507) served as controls. Anti‐phospholipid antibodies (aPL) were analysed by fluoroenzyme‐immunoassays detecting aCL/anti‐β₂GPI. Seventy‐six (14%) SLE cases fulfilled the Sydney APS‐criteria, and ≥ 1 aCL/anti‐β₂GPI isotype (IgG/IgA/IgM) occurred in 138 SLE patients (26%). Forty‐five (9%) of the SLE cases had IgA‐aCL, 20 of whom (4%) lacked IgG‐/IgM‐aCL. Seventy‐four (14%) tested positive for IgA anti‐β₂GPI, 34 (6%) being seronegative regarding IgG/IgM anti‐β₂GPI. Six (1%) had APS manifestations but were seropositive regarding IgA‐aCL and/or IgA anti‐β₂GPI in the absence of IgG/IgM‐aPL and LA. Positive LA and IgG‐aPL tests were associated with most APS‐related events and organ damage. Exclusive IgA anti‐β₂GPI occurrence associated inversely with Caucasian ethnicity [odds ratio (OR) = 0·21, 95% confidence interval (CI) = 0·06–0·72) and photosensitivity (OR = 0·19, 95% CI = 0·05–0·72). Nephritis, smoking, LA‐positivity and statin/corticosteroid‐medication associated strongly with organ damage, whereas hydroxychloroquine‐medication was protective. In conclusion, IgA‐aPL is not rare in SLE (16%) and IgA‐aPL analysis may have additional value among SLE cases with suspected APS testing negative for other isotypes of aPL and LA.     

IgG2 subclass restriction of anti-β2 glycoprotein 1 antibodies in autoimmune patients

The IgG subclass and light chain distribution of antiphospholipid antibodies (aPL) occurring in autoimmune patients were determined by means of two radioimmunoassays using either cardiolipinor β₂ glycoprotein 1 (β₂GP1)-coated microtitre plates and mouse MoAbs. Of 50 sera selected for positivity of anticardiolipin antibodies (ACA) of the IgG isotype, 32 (64%) possessed anti-β₂GPl antibodies and their presence was closely associated with clinical features of the antiphospholipid syndrome. Good correlations were found between ACA and anti-β₂GP1 antibodies when considering antibody level and patterns of light chain and IgG subclass, suggesting that, overall, the same antibodies were being measured. Light chain analysis showed the polyclonal origin of these antibodies and, in most sera, a trend towards use of λ chain. Among sera positive for anti-β₂GP1 antibodies, IgG2 was the major subclass reactive with β₂GP1 and cardiolipin (87% and 74β₂ of the IgG antibody activity, respectively). In contrast, in the group of 18 sera lacking anti-β₂GP1 antibodies, ACA were largely restricted to lgG3, with a lesser contribution by IgGl. A few selected sera from the anti-β₂GP1-positive group were shown to contain mixtures of antibodies that required β₂GP1 (restricted to IgG2 present in large amounts) and did not require this cofactor (restricted to IgG3 and/or IgG1 present in low amounts) for their reactivity with cardiolipin. There was no contribution of glycosylation to the epitopes recognized by anti-β₂GP1 antibodies, even though human anti-carbohydrate antibodies are restricted to the IgG2 subclass. These findings further emphasize the intra- and interindividual heterogeneity of aPL, and should help to discriminate clinically relevant specificies.     

Anti‐citrullinated glucose‐6‐phosphate isomerase peptide antibodies in patients with rheumatoid arthritis are associated with HLA‐DRB1 shared epitope alleles and disease activity

To identify and characterize anti‐citrullinated glucose‐6‐phosphate isomerase (GPI) peptide antibodies in patients with rheumatoid arthritis (RA). Nine GPI arginine‐bearing peptides in human GPI protein were selected and cyclic citrullinated GPI peptides (CCG‐1–9) were constructed. Samples were obtained from RA (n = 208), systemic lupus erythematosus (SLE) (n = 101), Sjögren's syndrome (SS; n = 101) and healthy controls (n = 174). Antibodies against CCG‐1–9 were measured, and anti‐citrullinated α‐enolase‐1 (CEP‐1), ‐cyclic citrullinated peptides (CCP) and ‐GPI proteins antibodies were also examined. Patients with RA were genotyped for HLA‐DRB1. The numbers of shared epitope (SE) alleles were counted and compared with those of the autoantibodies. Rabbit GPI was citrullinated with rabbit peptidylarginine deiminase and immunoblot analysis of RA sera performed. The levels of autoantibodies were compared before and after treatment with TNF antagonists in 58 RA patients. Anti‐CCG‐2, ‐4 and ‐7 antibodies were detected in 25·5, 33·2 and 37·0% patients with RA, respectively, and these antibodies were very specific for RA (specificity, 98·1–99·7%). Altogether, 44·2, 86·1 and 13·9% of RA sera were positive for anti‐CEP‐1, ‐CCP and ‐GPI protein antibodies, respectively. Anti‐CCG‐2, ‐4 and ‐7 antibodies were correlated with anti‐CCP and anti‐CEP‐1 antibodies and with the presence of HLA‐DRB1 SE alleles. Citrullinated GPI protein was detected using RA sera. Treatment with tumour necrosis factor antagonists reduced significantly the levels of anti‐CCG‐2 and ‐7 but not of anti‐CEP‐1 antibodies. This is the first report documenting the presence of anti‐CCG antibodies in RA. Anti‐CCG‐2 and ‐7 antibodies could be considered as markers for the diagnosis of RA and its disease activity.     

Toll-like receptor (TLR)-4 mediates anti-β2GPI/β2GPI-induced tissue factor expression in THP-1 cells

Our previous study demonstrated that annexin A2 (ANX2) on cell surface could function as a mediator and stimulate tissue factor (TF) expression of monocytes by anti‐β₂‐glycoprotein I/β₂‐glycoprotein I complex (anti‐β₂GPI/β₂GPI). However, ANX2 is not a transmembrane protein and lacks the intracellular signal transduction pathway. Growing evidence suggests that Toll‐like receptor 4 (TLR‐4) might act as an ‘adaptor’ for intracellular signal transduction in anti‐β₂GPI/β₂GPI‐induced TF expressing cells. In the current study, we investigated the roles of TLR‐4 and its related molecules, myeloid differentiation protein 2 (MD‐2) and myeloid differentiation factor 88 (MyD88), in anti‐β₂GPI/β₂GPI‐induced TF expressing human monocytic‐derived THP‐1 (human acute monocytic leukaemia) cells. The relationship of TLR‐4 and ANX2 in this process was also explored. Along with TF, expression of TLR‐4, MD‐2 and MyD88 in THP‐1 cells increased significantly when treated by anti‐β₂GPI (10 µg/ml)/β₂GPI (100 µg/ml) complex. The addition of paclitaxel, which competes with the MD‐2 ligand, could inhibit the effects of anti‐β₂GPI/β₂GPI on TLR‐4, MD‐2, MyD88 and TF expression. Both ANX2 and TLR‐4 in THP‐1 cell lysates could bind to β₂GPI that had been conjugated to a column (β₂GPI‐Affi‐Gel). Furthermore, TLR‐4, MD‐2, MyD88 and TF expression was remarkably diminished in THP‐1 cells infected with ANX2‐specific RNA interference (RNAi) lentivirus (LV‐RNAi‐ANX2), in spite of treatment with a similar concentration of anti‐β₂GPI/β₂GPI complex. These results indicate that TLR‐4 and its signal transduction pathway contribute to anti‐β₂GPI/β₂GPI‐induced TF expression in THP‐1 cells, and the effects of TLR‐4 with ANX2 are tightly co‐operative.     

Patients with inflammatory bowel disease may have a transforming growth factor‐β‐, interleukin (IL)‐2‐ or IL‐10‐deficient state induced by intrinsic neutralizing antibodies

Ulcerative colitis (UC) and Crohn's disease (CD) are considered to be immunologically mediated disorders that share certain features with murine models of colitis. Whether any of these models are physiologically relevant to the human condition remains controversial. The hypothesis is that increased amounts of antibodies neutralizing transforming growth factor (TGF)‐β, interleukin (IL)‐2 or IL‐10 create a relative immunodeficient state in inflammatory bowel disease (IBD) that predisposes to disease. To evaluate this, serum samples from patients with UC or CD and from normal healthy individuals were studied by enzyme‐linked immunosorbent assays. Antibodies recognizing TGF‐β were most prevalent in UC (P < 0·01); anti‐IL‐10 antibodies were elevated in CD (P < 0·05), while anti‐IL‐2 antibodies were the same for all three groups. Importantly, the percentage of IBD patients with at least one of the antibody levels greater than any control value was 30% for UC and 33% for CD. To verify the presence of these antibodies, immobilized TGF‐β was exposed to UC sera and the attached proteins identified by Western blot assay. The proteins proved to be exclusively immunoglobulin (Ig) G. To evaluate the neutralizing activity of these antibodies, cytokine‐specific IgG from subjects in each group of patients was incubated with TGF‐β, IL‐2 or IL‐10 before addition to a bioassay with changes in viability determined by a colorimetric analysis. Antibodies from most individuals in all three groups neutralized the action of each cytokine. This study shows that about one‐third of IBD patients may have a relative deficiency of TGF‐β, IL‐2 or IL‐10 due to an increase in neutralizing antibodies in their sera.     

Effect of Antiphospholipid Antibodies on β2Glycoprotein I-Phospholipid Interaction

PROBLEM: β₂ glycoprotein I (β₂GPI) physiologically binds to negatively charged phospholipids (PLs) and is a natural regulator of the coagulation cascade. Thrombotic clinical complications and recurrent fetal loss associated with autoimmune antiphospholipid (aPL) antibodies are thought to be related to their binding to β₂GPI-PL complex and interference with the physiological function of β₂GPI. METHOD OF STUDY: To investigate the effect of aPL on β₂GPI-PL interaction, we studied the binding of biotinylated β₂GPI to cardiolipin (CL) by enzyme-linked immunosorbent assay (ELISA) in the presence and absence of purified aPL immunoglobulin G (IgG) antibodies. RESULTS: Adding five different aPL IgG antibodies with different levels of aPL activity isolated from the sera of five patients with aPL-associated recurrent fetal death greatly increased the binding of biotinylated β₂GPI to CL-coated plates. The optical densities (ODs) were 0.635, 0.890, and 1.265 in the presence of three aPL IgG antibodies, compared to 0.425 in the absence of aPL IgG. In contrast, normal human IgG had no enhancing effect. The OD was 0.480 and 0.425, respectively. The enhancement of β₂GPI binding to CL by aPL IgG correlated with the titers of aPL antibodies. The use of phosphate-buffered saline with increasing salt concentrations as a washing buffer for the ELISA resulted in more stable binding of β₂GPI to PL in the presence of aPL IgG. CONCLUSIONS: These findings suggest that the binding of autoimmune aPL antibodies to β₂GPI-PL complex results in abnormally tighter interaction between β₂GPI and PLs, which may lead to physiological dysfunction of β₂GPI as a regulator of coagulation.     

Behcet's disease and pregnancy—a case report and literature review

This case study reports on a rare case of a woman with Behcet's disease (BD), uterine malformation and antiphospholipid syndrome, who successfully delivered a baby without any complications during the perinatal period. The woman, who was diagnosed with BD with relapsing oral, ocular, and genital involvement 8 years ago, registered in our clinic with a history of two inevitable miscarriages. Laboratory findings were positive for anti‐β₂‐glycoprotein I antibodies (anti‐β₂‐GP‐I). Three‐dimensional ultrasound showed that her uterus was unicornuate, with only a normal left side. After treatment, the woman had a cesarean section for breech presentation of a healthy male infant weighing 2700 g. The postpartum period was uneventful. The possible effects of BD on pregnancy outcomes and how to manage BD patients are discussed with a review of the literature.     

APhL antibody ELISA as an alternative to anticardiolipin test for the diagnosis of antiphospholipid syndrome

Background

Persistent levels of antiphospholipid (aPL) antibodies [lupus anticoagulant (LA), anticardiolipin (aCL), anti-beta 2 glycoprotein I (aβ₂GPI) IgG and/or IgM] in association with clinical features of thrombosis and/or pregnancy associated morbidity are indicative of antiphospholipid syndrome (APS). Of the aPL antibodies, aCL is the most sensitive for APS, however, their lack of specificity constitute a laboratory and clinical challenge. IgG/IgM antibodies directed against APhL (a mixture of phospholipids) has been reported to predict APS more reliably than aCL tests. The main objective of this study was to evaluate the performance characteristics of the APhL IgG/IgM ELISA, relative to the aCL and aβ₂GPI tests.

Methods

Sixteen (16) clinically confirmed APS and 85 previously tested serum (PTS) samples for aCL and aβ₂GPI IgG/IgM antibodies were evaluated with the APhL IgG/IgM ELISA. Clinical specificity was determined in 100 serum samples (50 healthy and 50 infectious disease controls [parvo- and syphilis-IgG/IgM positive]).

Results

The IgG antibody prevalence for aCL and APhL in the APS and PST groups was comparable with marginal differences in clinical specificities. In contrast to the aCL IgM ELISA, the APhL test showed improved clinical specificities (72% aCL vs 94% APhL in the healthy controls; 38% aCL vs 78% APhL in the infectious disease controls) with implications for increased reliability in the diagnosis of APS. The overall agreement of the APhL with the aCL or aβ₂GPI for the IgG tests was 89% and 85% respectively, and that of the APhL IgM to the aCL or aβ₂GPI IgM tests was 72% and 86% respectively.

Conclusion

Routine use of the APhL IgG/IgM ELISA may substantially reduce the high number of false positives associated with the aCL test without loss in sensitivity for APS.     

Correlation Between β2-Glycoprotein Antibodies and Antiphospholipid Antibodies in Patients with Reproductive Failure

PROBLEM: Antiphospholipid antibodies (APAs) are important in the etiology of reproductive failure. Studies have shown that binding proteins are necessary for the detection of APAs. One of these, β₂-glycoprotein, has been shown to be necessary for detection of anticardiolipin antibodies. It is felt that some APAs may be directed to the binding protein itself, or to a combination of the binding protein and phospholipid. METHOD OF STUDY: In this study, a comparison of APAs vs. anti β₂-glycoprotein antibodies was performed on the sera of 123 women younger than 40 years of age with a history of reproductive failure. Antibodies to six phospholipid epitopes, cardiolipin, phosphatidyle-thanolamine, phosphatidylserine, phosphatidylinositol, phosphatidic acid, phosphatidylglycerol, and phosphatidylserine, were measured. RESULTS: Of the 123 women tested, 33 had one or more positive immunoglobulin (Ig)G antibodies to phospholipids, of which 9 were to cardiolipin. However, only 1 of 123 women had IgG antibodies to β₂-glycoprotein and she was APA negative. Thirty-eight of 123 women had one or more IgM antibodies to phospholipids, with none directed to cardiolipin IgM. In contrast, only 8 of the 123 women had IgM antibodies to β₂-glycoprotein. Five of the eight patients had IgM APA; 4 of 5 had IgM antibodies to PE, 1 to PI. CONCLUSIONS: There is no correlation between β₂-glycoprotein antibodies and APA status in this population. To date, our most sensitive test for detecting phospholipid autoimmune-mediated in vitro fertilization failure still appears to be the ELISA assay for APA.     

Antibodies to β2-glycoprotein I—a specific marker for the antiphospholipid syndrome

The antiphospholipid syndrome is a disorder characterized by recurrent thrombosis and the presence of antibodies specific to phospholipids. However, the diagnosis of this syndrome is hampered by the lack of a specific laboratory test. In this study an ELISA for the measurement of antibodies to solid-phase β₂-glycoprotein I (β₂-GPI) was established and compared with anticardiolipin antibodies for diagnosis of antiphospholipid syndrome. Significantly elevated levels of antibodies to β₂-GPI were found in all patients with definite antiphospholipid syndrome (median = 91 AU). Marginally elevated levels of antibodies to β₂-GPI were observed in 5% of patients with systemic lupus erythematosus (SLE; median = 4 AU), 1% with stroke (median = 3 AU), 13% with infectious mononucleosis (median = 3 AU), 10% with HIV infection (median = 3 AU) and 8% with VDRL false-positive serology for syphilis (median = 4 AU), but not in patients with rheumatoid factor, syphilis or carotid artery stenosis. In contrast, significantly raised levels of anticardiolipin antibodies were observed in 100% of patients with definite antiphospholipid syndrome, 30% with SLE, 88% with HIV infection, 94% with syphilis, 62% with infectious mononucleosis, 9% with rheumatoid factor-positive sera, 74% VDRL false-positive serology for syphilis, 47% with stroke and 0% with carotid artery stenosis. This solid-phase assay for antibodies to β₂-GPI is highly specific for the antiphospholipid syndrome and represents an advance in the laboratory diagnosis of this disorder.     

Anti‐transglutaminase antibodies in non‐coeliac children suffering from infectious diseases

Anti‐transglutaminase antibodies are the diagnostic markers of coeliac disease. A role is suggested for infectious agents in the production of anti‐transglutaminase antibodies. The aim was to measure positive anti‐transglutaminase antibody levels in children with infectious diseases and to compare immunological and biological characteristics of the anti‐transglutaminase antibodies derived from these children with that from coeliac patients. Two hundred and twenty‐two children suffering from infectious diseases were enrolled prospectively along with seven biopsy‐proven coeliacs. Serum samples were tested for anti‐transglutaminase antibodies and anti‐endomysium antibodies; positive samples were tested for coeliac‐related human leucocyte antigen (HLA)‐DQ2/8 and anti‐viral antibodies. Purified anti‐transglutaminase antibodies from the two study groups were tested for urea‐dependent avidity, and their ability to induce cytoskeletal rearrangement and to modulate cell‐cycle in Caco‐2 cells, using phalloidin staining and bromodeoxyuridine incorporation assays, respectively. Nine of 222 children (4%) tested positive to anti‐transglutaminase, one of whom also tested positive for anti‐endomysium antibodies. This patient was positive for HLA‐DQ2 and was diagnosed as coeliac following intestinal biopsy. Of the eight remaining children, two were positive for HLA‐DQ8. Levels of anti‐transglutaminase returned to normal in all subjects, despite a gluten‐containing diet. Purified anti‐transglutaminase of the two study groups induced actin rearrangements and cell‐cycle progression. During an infectious disease, anti‐transglutaminase antibodies can be produced temporarily and independently of gluten. The infection‐triggered anti‐transglutaminase antibodies have the same biological properties as that of the coeliacs, with the same in‐vivo potential for damage.     

Antiphospholipid Antibodies in Patients With Preeclampsia

PROBLEM: To determine the incidence of anticardiolipin and antiphosphatidylserine antibodies in women with preeclampsia. METHODS: Sera from 100 women with preeclampsia and 100 normotensive pregnant women in the third trimester were assayed for anticardiolipin and antiphosphatidylserine antibodies. RESULTS: Antiphosphatidylserine antibodies were positive for IgM in 1 patient (1%) and for IgG in 4 patients (4%). IgM antibodies to cardiolipin were positive in two patients (2%) while IgG antibodies to cardiolipin were positive in nine patients (9%). Only 3% of the control women were positive for antiphospholipid antibodies. None of the patients or controls had positive levels of IgA anticardiolipin or antiphosphatidylserine antibodies. CONCLUSIONS: Elevated levels of IgG or IgM antibodies to cardiolipin and phosphatidylserine were detected in 11/100 (11%) of women diagnosed with preeclampsia in the third trimester compared to only 3/100 (3%) positive in controls (P < 0.05). These findings suggest that antiphospholipid antibodies may play a pathogenic role in some women with preeclampsia.     

Anti‐C1q autoantibodies are linked to autoimmune thyroid disorders in pregnant women

Anti‐C1q antibodies (anti‐C1q) have been implicated in the pathogenesis of autoimmune diseases, including autoimmune thyroid disorders (AITD). The aim of this study was to evaluate the association between anti‐C1q and thyroid function in pregnancy‐associated AITD. In 96 pregnant women screened positive for AITD (thyroid dysfunction and/or antibodies against thyroperoxidase – TPOAb), anti‐C1q were measured during the 9‐11th gestational week and after delivery (median 16 months after delivery), and compared to the corresponding serum levels of thyroid hormones. As controls, 80 healthy pregnant women, 72 non‐pregnant AITD patients and 72 blood donors were included. In the non‐pregnant AITD group, two serum samples ≥ 6 months apart were analysed. Compared to blood donors, anti‐C1q levels were substantially higher in all pregnant women analysed. In pregnancy, anti‐C1q levels were higher in the TPOAb‐positive women than in controls (37 versus 17·5%, P < 0·0001). Anti‐C1q‐positive pregnant women screened positive for AITD had higher thyroid‐stimulating hormone (TSH) levels than anti‐C1q‐negative women (2·41 versus 1·94 mU/l, P = 0·01), and TSH correlated positively with anti‐C1q (r = 0·226, P = 0·045) in the TPOAb‐positive women. After delivery, serum levels of anti‐C1q decreased in the positively screened TPOAb‐negative women (8·8 versus 5·9 U/l, P = 0·002), but not in the TPOAb‐positive ones, and they no longer correlated with TSH. Anti‐C1q antibody levels increase during pregnancy in general and even more in the context of AITD, where they correlate with thyroid stimulating hormone levels.     

Anti‐fibrotic mechanisms of angiotensin AT2‐receptor stimulation

The angiotensin AT₂‐receptor is a main receptor of the protective arm of the renin‐angiotensin system. Understanding of this unconventional G‐protein coupled receptor has significantly advanced during the past decade, largely because of the availability of a selective non‐peptide AT₂‐receptor agonist, which allowed the conduct of a multitude of studies in animal disease models. This article reviews such preclinical studies that in their entirety provide strong evidence for an anti‐fibrotic effect mediated by activation of the AT₂‐receptor. Prevention of the development of fibrosis by AT₂‐receptor stimulation has been demonstrated in lungs, heart, blood vessels, kidney, pancreas and skin. In lungs, AT₂‐receptor stimulation was even able to reverse existing fibrosis. The article further discusses intracellular signalling mechanisms mediating the AT₂‐receptor‐coupled anti‐fibrotic effect, including activation of phosphatases and subsequent interference with pro‐fibrotic signalling pathways, induction of matrix‐metalloproteinases and hetero‐dimerization with the AT₁‐receptor, the TGF‐βRII‐receptor or the RXFP1‐receptor for relaxin. Knowledge of the anti‐fibrotic effects of the AT₂‐receptor is of particular relevance because drugs targeting this receptor have entered clinical development for indications involving fibrotic diseases.     

Anti-prothrombin antibodies are associated with adverse pregnancy outcome

Citation Marozio L, Curti A, Botta G, Canuto EM, Salton L, Tavella AM, Benedetto C. Anti‐prothrombin antibodies are associated with adverse pregnancy outcome. Am J Reprod Immunol 2011; 66: 404–409 Problem Women with antiphospholipid antibodies (aPL) such as lupus anticoagulant, anticardiolipin antibodies, and anti‐β₂ glycoprotein‐1 antibodies are at high risk of late pregnancy complications, such as severe pre‐eclampsia, placental insufficiency, and fetal loss. It has been observed that aPL consists of a heterogeneous group of antibodies targeting several phospholipid‐binding plasma proteins, including also anti‐prothrombin (anti‐PT), anti‐protein S (anti‐PS), and anti‐protein C (anti‐PC) antibodies. Their potential role in late pregnancy complications is not known. The aim of this work was to investigate the association between those autoantibodies and histories for adverse pregnancy outcome. Method of study Anti‐PT, anti‐PS, and anti‐PC antibodies were evaluated in 163 patients with previous severe pre‐eclampsia, fetal death, and/or placental abruption and in as many women with previous uneventful pregnancies, negative for aPL. Results The prevalence of anti‐PT antibodies was higher in cases than in controls (OR, 95% CI: 10.92, 4.52–26.38). The highest prevalence was observed in subjects with fetal death. Conclusion Anti‐PT antibodies appear to be associated with adverse pregnancy outcome, irrespectively of aPL.     

Anti-annexin II Antibodies in Systemic Autoimmune Diseases and Antiphospholipid Syndrome

Objectives

The objective of this study were (1) to evaluate the prevalence of anti-annexin II antibodies in patients with various autoimmune diseases and antiphospholipid syndrome and (2) to correlate anti-annexin II antibodies with anti-phospholipid antibodies.

Materials and Methods

Anti-annexin II antibodies and anti-phospholipid were detected, using an enzyme-linked immunosorbent assay, in the serum of patients with primary antiphospholipid syndrome (n?=?16), systemic lupus erythematosus (n?=?53), primary Sjögren syndrome (n?=?71), systemic sclerosis (n?=?17), systemic vasculitis (n?=?18), and rheumatoid arthritis (n?=?119). Healthy blood donors (n?=?99) were used as controls.

Results

Anti-annexin II antibodies were significantly more prevalent in patients with connective tissue diseases (8.5%), especially antiphospholipid syndrome (14.8%) and rheumatoid arthritis (10%), than in controls (2%). An inverse correlation was observed between anti-annexin II antibodies and antiphospholipid antibodies.

Conclusion

Annexin II can be recognized by antibodies in serum from patients with systemic autoimmune disorders. Further studies are required to determine the clinical significance of anti-annexin II antibodies in rheumatoid arthritis and to determine their diagnostic value in discriminating clinical subgroups of patients with antiphospholipid syndrome.     

Diagnostic and prognostic values of anti glucose-6-phosphate isomerase antibodies in community-recruited patients with very early arthritis

The objective of this study was to determine the diagnostic and prognostic values of antiglucose‐6‐phosphate isomerase (GPI) antibodies in patients with very early arthritis. Anti‐GPI antibodies were measured by ELISA using purified GPI from rabbit muscle in: (i) 383 sera from healthy blood donors (n = 120), well‐established rheumatoid arthritis (RA) (n = 99) and non‐RA differentiated arthritis (NRADA) (n = 164) patients; (ii) 195 sera obtained from community‐recruited patients with very early inflammatory arthritis (VErA cohort) that were studied for 1 year and classified as having RA (n = 116), NRADA (n = 41), and undifferentiated arthritis (UA) (n = 38) after the follow‐up period. The criterion for severity was the progression of radiographic damage. Prevalence of anti‐GPI antibodies was significantly higher in well‐established RA patients (45·4%) compared to healthy subjects (2·5%). Anti‐GPI antibodies were also present in sera from NRADA: systemic lupus erythematosus 53%, polymyositis 45·4%, adult‐onset Still's disease 44%, systemic sclerosis 42·8%, spondylarthropathies 25% and primary Sjögren’s syndrome 5·8%. No significant association was found between the presence of anti‐GPI antibodies and the 3 diagnostic groups from the VErA cohort. No correlation was observed between anti‐GPI and autoantibodies usually associated with RA. Anti‐GPI antibodies were not predictive of radiological progression in patients with very early arthritis. Thus, anti‐GPI antibodies are not useful for discriminating RA from non‐RA rheumatic diseases and do not constitute a predictive factor of structural damage.     

Submandibular gland morphogenesis: Stage‐specific expression of TGF‐α/EGF,IGF, TGF‐β, TNF,and IL‐6 signal transduction in normal embryonic mice and the phenotypic effects of TGF‐β2, TGF‐β3, and EGF‐r null mutations

Branching morphogenesis of the mouse submandibular gland (SMG) is dependent on cell‐cell conversations between and within epithelium and mesenchyme. Such conversations are typically mediated in other branching organs (lung, mammary glands, etc.) by hormones, growth factors, cytokines, and the like in such a way as to translate endocrine, autocrine, and paracrine signals into specific gene responses regulating cell division, apoptosis, and histodifferentiation. We report here the protein expression in embryonic SMGs of four signal transduction pathways: TGF‐α/EGF/EGF‐R; IGF‐II/IGF‐IR/IGF‐IIR; TGF‐βs and cognate receptors; TNF, IL‐6, and cognate receptors. Their in vivo spatiotemporal expression is correlated with specific stages of progressive SMG development and particular patterns of cell proliferation, apoptosis, and mucin expression. Functional necessity regarding several of these pathways was assessed in mice with relevant null mutations (TGF‐β2, TGF‐β₃, EGF‐R). Among many observations, the following seem of particular importance: (1) TGF‐α and EGF‐R, but not EGF, are found in the Initial and Pseudoglandular Stages of SMG development; (2) ductal and presumptive acini lumena formation was associated with apoptosis and TNF/TNF‐R1 signalling; (3) TGF‐β2 and TGF‐β3 null mice have normal SMG phenotypes, suggesting the presence of other pathways of mitostasis; (4) EGF‐R null mice displayed an abnormal SMG phenotype consisting of decreased branching. These and other findings provide insight into the design of future functional studies. Anat Rec 256:252–268, 1999. © 1999 Wiley‐Liss, Inc.     

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.