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OBJECTIVE: Clinical evidence and experimental evidence suggest that anti-Ro/La autoantibodies are necessary but not sufficient for the development of congenital complete heart block (CCHB). Maternal, fetal, and environmental factors may also contribute to heart damage in CCHB. The aim of our study was to investigate polymorphisms of transforming growth factor beta1 (TGFbeta1) and tumor necrosis factor alpha (TNFalpha) genes in twins and triplets discordant for CCHB whose mothers are anti-Ro/La positive. METHODS: We studied 2 families in which 1 of the mothers gave birth to triplets and the other gave birth to twins. Only 1 child in each family was affected by CCHB, although 1 of the triplets had incomplete heart block. We analyzed TNFalpha and TGFbeta1 polymorphisms in the 2 babies with CCHB and their siblings. TNFalpha polymorphisms at the promoter region and TGFbeta1 polymorphisms at codons 10 and 25 were determined using polymerase chain reaction-restriction fragment length polymorphism analysis. In addition, the production of TGFbeta1 and TNFalpha by resting or mitogen-stimulated peripheral blood mononuclear cells in cell culture supernatants was evaluated by enzyme-linked immunosorbent assay. RESULTS: The profibrotic TGFbeta1 genotype was detected in the twin with CCHB but not in the healthy twin, while all of the triplets displayed the same TGFbeta1 genotype at codon 10. Peripheral blood mononuclear cells from the children with CCHB displayed higher spontaneous and mitogen-stimulated TGFbeta1 secretion than was observed in their siblings. No differences regarding TNFalpha polymorphisms and secretion of TNFalpha were observed. CONCLUSION: The results of this study suggest that, besides anti-Ro/La autoantibodies, a fetal profibrotic response might contribute to the development of CCHB, but additional pathogenic mechanism(s) are also likely to play a role. [ABSTRACT FROM AUTHOR]

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombotic events and/or pregnancy morbidity in the persistent presence of antiphospholipid antibodies (aPL). aPL targeting β2 glycoprotein I (anti-β2GPI Abs) provide the main pathogenic autoantibody subset. In monocytes, platelets and endothelial cells (ECs), the interaction of circulating aPL with membrane-bound β2GPI results in cell activation, and EC perturbation provides an important player in clotting. Several receptors have been suggested to mediate β2GPI/EC binding. AnnexinA2 provides a high-affinity binding site for β2GPI but, since it does not span the cell membrane, an adaptor protein is required to trigger signal. Consistent evidence supports the role of Toll-like receptor (TLR) 4 as co-receptor for β2GPI on ECs. β2GPI was recently reported to behave as lipopolysaccharide (LPS) scavenger. In monocytes, TLR4 activation was shown to be apparent, due to LPS/β2GPI complexes. Conversely, our findings in ECs demonstrate that β2GPI interacts directly with TLR4, and that such interaction may contribute to β2GPI-dependent aPL-mediated EC activation. LPS enhanced anti-β2GPI Ab binding to EC only at cell-activating concentrations, able to up-regulate TLR4. This in vitro model may explain why LPS behaves as a second hit increasing the expression of β2GPI in vascular tissues and triggering aPL-mediated thrombosis in vivo. [ABSTRACT FROM PUBLISHER]

OBJECTIVE: Heparin-binding epidermal growth factor-like growth factor (HB-EGF) plays a role in blastocyst implantation and is down-regulated in preeclampsia and in hypertensive pregnancy disorders associated with defective extravillous trophoblast invasion. Defective placentation and severe preeclampsia are also features of the antiphospholipid syndrome (APS). The purpose of this study was to investigate whether abnormal HB-EGF expression plays a pathogenic role in antiphospholipid antibody (aPL)-mediated defective placentation. METHODS: HB-EGF expression in placental tissue was evaluated by Western blotting and messenger RNA analysis in normal and APS placentae. Polyclonal IgG fractions or monoclonal beta(2)-glycoprotein I-dependent aPL and their respective controls were investigated for the following 4 features: their binding to human trophoblast monolayers, as determined by cell enzyme-linked immunosorbent assay (ELISA); their effect on HB-EGF expression by Western blotting in trophoblast cell extracts as well as by ELISA as a protein secreted in the culture supernatants; their inhibitory effect on in vitro trophoblast invasiveness, as evaluated by Matrigel assay; and their inhibitory effect on matrix metalloproteinase (MMP) levels, as measured by gelatin zymography. Experiments were also performed in the presence of serial concentrations of heparin or recombinant HB-EGF. RESULTS: Placental APS tissue displayed reduced expression of HB-EGF. Polyclonal and monoclonal aPL bound to trophoblast monolayers and significantly reduced the in vitro synthesis and secretion of HB-EGF. Heparin inhibited aPL binding and restored HB-EGF expression in a dose-dependent manner. Addition of recombinant HB-EGF reduced the in vitro aPL-induced inhibition of Matrigel invasiveness as well as MMP-2 levels. CONCLUSION: These preliminary findings suggest that the reduction of aPL-mediated HB-EGF represents an additional mechanism that is responsible for the defective placentation associated with APS and that heparin protects from aPL-induced damage by inhibiting antibody binding. [ABSTRACT FROM AUTHOR]

The international consensus for the classification of antiphospholipid syndrome (APS) requires clinical and laboratory criteria to be considered at an equal level for diagnosing APS. Thus, detection of antiphospholipid antibodies (aPL) being a hallmark of APS has been the object of intensive investigation over the past 40 years. However, appropriate detection of aPL still remains a laboratory challenge due to their heterogeneity comprising autoantibodies reactive to different phospholipid-binding plasma proteins, such as beta-2 glycoprotein I (β2GPI) and prothrombin. The relevance of aPL interacting with phospholipids other than cardiolipin (CL, diphosphatidylglycerol), such as phosphatidylserine (PS), remains elusive with regard to the diagnosis of APS. Recently, the concept of aPL profiling has been introduced to assess the risk of thrombotic complications in patients with APS. New assay techniques, apart from enzyme-linked immunosorbent assays (ELISAs) recommended by the international consensus for the classification of APS, have been proposed for multiplexing of aPL testing. Line immunoassays (LIAs) employing a novel hydrophobic solid phase for the simultaneous detection of different aPL seem to be an intriguing alternative. We evaluated a novel multiplex LIA employing a hydrophobic membrane coated with different phospholipid (PL)-binding proteins or PLs. The performance characteristics of this new multiplexing assay technique demonstrated its usefulness for aPL profiling. [ABSTRACT FROM PUBLISHER]

Beta2 glycoprotein I (β2GPI)-dependent antiphospholipid antibodies (aPLs) are the main pathogenic autoantibody population and at the same time the laboratory diagnostic tool for the antiphospholipid syndrome (APS).These antibodies are responsible for both the vascular and the obstetric manifestations of the syndrome but the pathogenic mechanisms behind these manifestations are not the same. For example, thrombotic events do not appear to play a major role in APS miscarriages and a direct reactivity of β2GPI-dependent aPLs on decidual and trophoblast cells was reported. A local expression of β2GPI on these tissues was reported both in physiological conditions and in APS women, thus explaining the local tropism of the autoantibodies.The two hit hypothesis was suggested to explain why the vascular manifestations of APS may occur only occasionally in spite of the persistent presence of aPLs. This is not apparently the case for the obstetric variant of the syndrome, making the difference even more striking. A different pathogenesis may also provide the rationale for the well-known fact that the vascular and the obstetric manifestations may occur independently although in a minority of cases. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM PUBLISHER]