N. Del Papa

Antiphospholipid antibodies affect trophoblast gonadotropin secretion and invasiveness by binding directly and through adhered β2‐glycoprotein I

OBJECTIVE To investigate the in vitro ability of antiphospholipid antibodies (aPL) to bind human trophoblast cells and to affect gonadotropin secretion and invasiveness. METHODS Antiphospholipid antibody IgG from women with recurrent miscarriages, beta2-glycoprotein I (beta2GPI)-independent IgG aPL human monoclonal antibody (mAb) (519), and IgM anti-beta2GPI human mAb (TMIG2) were investigated for their binding to trophoblasts cultured for various amounts of time, their ability to affect invasiveness of Matrigel-coated filters, and their release of human chorionic gonadotropin (hCG). RESULTS Polyclonal IgG aPL, as well as mAb 519 and TMIG2, bound to trophoblasts, the highest binding being found when cells displayed the greatest amount of syncytium formation. TM1G2 binding was found to be betaGPI dependent. Both polyclonal and monoclonal aPL, but not the controls, significantly reduced hCG release and Matrigel invasiveness. CONCLUSION These findings suggest that aPL recognition of both anionic PL and adhered beta2GPI on trophoblast cell structures might represent a potential pathogenetic mechanism for defective placentation in women with the antiphospholipid syndrome.

Prevalence and factors associated with left ventricular dysfunction in the EULAR Scleroderma Trial and Research group (EUSTAR) database of patients with systemic sclerosis

Objectives: To measure the prevalence of, and factors associated with, left ventricular (LV) dysfunction in systemic sclerosis (SSc). Methods: The EUSTAR database was first searched. A case-control study of a patient subset was then performed to further identify independent factors associated with LV dysfunction by simple and multiple regression. Results: Of 7073 patients, 383 (5.4%) had an LV ejection fraction (EF) of <55%. By multiple regression analysis, age, sex, diffuse cutaneous disease, disease duration, digital ulcerations, renal and muscle involvement, disease activity score, pulmonary fibrosis and pulmonary arterial hypertension were associated with LV dysfunction. In the second phase, 129 patients with SSc with LVEF <55% were compared with 256 patients with SSc with normal LVEF. Male sex (OR 3.48; 95% CI 1.74 to 6.98), age (OR 1.03; 95% CI 1.01 to 1.06), digital ulcerations (OR 1.91; 95% CI 1.05 to 3.50), myositis (OR 2.88; 95% CI 1.15 to 7.19) and use of calcium channel blockers (OR 0.41; 95% CI 0.22 to 0.74) were independent factors associated with LV dysfunction. Conclusion: The prevalence of LV dysfunction in SSc is 5.4%. Age, male gender, digital ulcerations, myositis and lung involvement are independently associated with an increased prevalence of LV dysfunction. Conversely, the use of calcium channel blockers may be protective.

Anti-endothelial cell IgG fractions from systemic lupus erythematosus patients bind to human endothelial cells and induce a pro-adhesive and a pro-infiammatory phenotype in vitro

Affinity purified immunoglobulin G (IgG) fractions from systemic lupus erythematosus (SLE) patients positive for anti-endothelial cell antibodies (AECA) bind human umbilical vein endothelial cell (HUVEC) monolayers. In vitro incubation of serial protein concentrations of SLE AECA IgG induces a dose-dependent endothelial activation: i) increase of functional adhesion of the monocytic cell line U937; ii) upregulation of E-Selectin, ICAM-1, VCAM-1 expression evaluated by a cell solid-phase enzyme linked immunoassay; and iii) increased secretion of interleukin (IL)-6 in the culture supernatants. Control experiments carried out with HUVEC monolayers incubated with IgG fractions from normal healthy controls or from AECA negative SLE sera do not affect at all endothelial adhesion molecule expression or pro-inflammatory cytokine secretion. The AECA IgG effects are not related to both anti-phospholipid or anti-DNA activities. Taken together the findings suggest that these autoantibodies might be important in recruiting and in activating mononuclear leukocytes responsible for vessel wall infiltration and raise the possibility that AECA might display a pathogenic role in SLE vessel damage.

Antibodies to endothelial cells in primary vasculitides mediate in vitro endothelial cytotoxicity in the presence of normal peripheral blood mononuclear cells

Twenty-eight out of 62 patients with Wegeners granulomatosis and micropolyarteritis display circulating antiendothelial cell antibodies (AECA) detectable by a cell surface radioimmunoassay. These antibodies do not induce an in vitro endothelial damage either alone or in the presence of fresh complement; however, 50% of IgG-AECA positive sera can be cytotoxic in the presence of human normal peripheral blood mononuclear cells (PBM) at high effector/target ratios. The specificity of the PBM-mediated cytotoxicity is supported by the absence of the phenomenon in AECA negative sera, by the disappearance of the lytic effect after absorption of AECA, and by the finding that cellular-mediated cytotoxicity can be reproduced by purified IgG-AECA positive fractions. On the contrary, polymorphonuclear leukocytes or adherent mononuclear cells are not involved in such a cytotoxic activity. AECA seem to be directed against determinants consitutively expressed on the endothelial surface since the activation of endothelial cells by interleukin-1 beta or interferon-gamma affects neither the antibody binding nor their ability to mediate 51Cr release in the presence of PBM. These findings favor the hypothesis for a possible direct pathogenetic role of circulating AECA in the in vivo vascular damage.

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

PROBLEM: To investigate the role of the plasma cofactor for antiphospholipid antibodies in antibody binding to endothelial cells.

Antibody to carbonic anhydrase II is present in primary biliary cirrhosis (PBC) irrespective of antimitochondrial antibody status

Antibody to carbonic anhydrase II, an enzyme abundantly present in biliary epithelium, has been proposed as a diagnostic marker for antimitochondrial antibody‐negative PBC. In this study we determine its prevalence and clinical significance in a large series of patients with antimitochondrial antibody‐positive and ‐negative PBC. Reactivity to carbonic anhydrase II was sought by Western immunoblotting in sera from 215 consecutive patients with PBC (26 antimitochondrial antibody‐negative), 13 with autoimmune hepatitis, 25 with primary Sjögrens syndrome (pSS), 12 with systemic sclerosis, 19 with systemic lupus erythematosus and 73 healthy subjects. The prevalence of antibody to carbonic anhydrase II (titre 1:100) in PBC was 8%. No specific reactivity to carbonic anhydrase II was found in antimitochondrial antibody‐negative PBC (7% versus 8% in antimitochondrial antibody‐positive PBC). Ascites (P = 0.006) and Sjögrens syndrome (SS) (P = 0.022) in PBC were significantly associated with presence of the antibody. In patients with SS associated with PBC, the prevalence (19%) was similar to that observed in pSS (16%). At a serum dilution of 1:40, the prevalence of positive sera in PBC rose to 27% but disease specificity was reduced. Our findings in a large population of PBC patients rule out a relation between presence of antibody to carbonic anhydrase II and lack of antimitochondrial antibody. The higher prevalence of ascites found in positive patients warrants further evaluation.

Comparison between iloprost and alprostadil in the treatment of Raynaud's phenomenon

Objective: The prostanoids iloprost and alprostadil are widely used to treat ischaemic changes in patients with Raynauds phenomenon (RP), but the optimal regimen is poorly defined. We evaluated whether there are differences between iloprost and alprostadil, in terms of either clinical efficacy or of laboratory data, with the aim of assisting in the treatment of connective tissue disease (CTD)‐associated RP. Methods: Twenty‐one women with CTD‐associated RP were given intravenous iloprost (11 patients) or alprostadil (10 patients) cyclically (5 consecutive days, followed by 1 day every 30 days). Clinical efficacy (RP symptoms, skin score, digital ulcers) and circulating levels of von Willebrand factor (VWf), tissue plasminogen activator (tPA), thrombomodulin (TM) and Type III procollagen N‐terminal propeptide (PIIINP) were evaluated by enzyme‐linked immunoassay at different intervals. Results: The overall benefits of iloprost and alprostadil were similar. RP improved in 45% versus 90% of patients; ulcers in 60% versus 40% of patients (iloprost versus alprostadil). Skin score did not significantly change with either drug. Circulating VWf decreased with either drug (iloprost −6.2%, alprostadil −9.4%), while tPA, TM, and PIIINP remained unchanged. Side effects were only minor and less frequent with alprostadil. Conclusion: Iloprost and alprostadil were both of benefit in CTD‐associated RP, without significant differences in either clinical efficacy or circulating markers. However, ease of handling and the lower price favours alprostadil.

In vitro type-1 and type-2 cytokine production in systemic lupus erythematosus: lack of relationship with clinical disease activity:

Objective: to investigate the relationship between disease activity and in vitro cytokine, soluble(s)CD23 and polyclonal and anti-DNA antibody production by PBMC from patients with active systemic lupus erythematosus (SLE). Methods: cytokines, sCD23 and immunoglobulins were estimated by ELISA in unstimulated and polyclonal mitogen-stimulated culture supernatants. Results: PHA-induced IL-2 and IFN-y production were decreased, whereas spontaneous and PHA-induced IL-6 and IL-10 production were increased in cultures of SLE lympho cytes. Conversely, spontaneous and PHA-stimulated IL-4 and sCD23 production was com parable between patients and controls. Finally, we found an increase in in vitro spontaneous polyclonal and anti-DNA IgG secretion. Conclusions: We demonstrated an expanded type-2 cytokine profile with no correlation with parameters of disease activity.

β2-Glycoprotein I as a 'cofactor' for anti-phospholipid reactivity with endothelial cells

β2-glycoprotein I (β2GPI) is a cofactor for anti-phospholipid (aPL) binding to cardiolipin (CL)-coated plates. β2GPI is also able to bind to endothelial cell (EC) membranes as supported by in-vivo as well as by in-vitro studies. The PL-binding site in the fifth domain of the molecule is involved in the adhesion to endothelium. Actually, specific mutations in this molecular portion abolish endothelium binding and a synthetic peptide spanning the sequence Glu274 –Cys288 of the CL-binding site displays comparable adhesion to EC monolayers. Heparan sulphate appears to be one of the anionic EC membrane structures with which cationic β2GPI interacts, as supported by studies with heparitinase-treated EC. β2GPI binding to EC might be related to its activity as endothelial growth factor or as a lipid-carrying glycoprotein. Adhesion of β2GPI to endothelial membranes offers suitable epitopes for circulating aPL that, once bound, can induce cell activation

Modulation of Endothelial Cell Function by Antiphospholipid Antibodies

β2-glycoprotein I (β2-GP-I) the plasma cofactor for anti-phospholipid antibodies adheres on the endothelial surfaces and can be recognized by anti-β2-GP-I antibodies naturally occurring in patients with the anti-phospholipid syndrome. As for the cofactor binding to cardiolipin- or gamma irradiated-plates, the endothelial binding is mediated by the so-called phospholipid binding site, a cationic structure able to react with anionic molecules. Endothelial monolayers appear to represent a substrate able to bind β2-GP-I and to present it in a suitable manner in order to allow the binding of anti-β2-GP-I β2 antibodies. The complex between β2-GP-I and the respective antibodies induce an endothelial cell activation as demonstrated by the up-regulation of adhesion molecule expression, the secretion of proinflammatory cytokines and the modulation of arachidonic acid metabolism. Taken together these findings strongly sustain a pivotal role for β2-GP-I in allowing antibody deposition on the endothelium and in affecting endothelial cell functions potentially responsible for a procoagulant state.