No description available.

An outline of the work contained in this thesis is presented. The first chapter is a critical review of the literature pertaining to the pathophysiological mechanisms operational with regards to the antiphospholipid syndrome (APS). The syndrome is characterised by venous and arterial thrombosis, and recurrent fetal loss, in association with the persistent presence of antibodies targeting the main autoantigen beta 2-glycoprotein I (β2GPI). The second chapter reviews the literature delineating the diverse physiological functions of β2GPI, and then relates them to its role in our current understanding of the pathophysiology of APS. The third chapter presents a critical review of the evidence base for the diagnosis and management of APS. The fourth chapter describes the interaction between β2GPI and the glycoprotein Ib alpha (GPIbα) subunit of the platelet receptor GPIb-IX-V. GPIbα is an important platelet adhesion receptor, which mediates multiple additional functions on the platelet surface, including binding coagulation factor XI (FXI). The implication of the interaction between β2GPI and GPIbα on platelet activation and the release of thromboxane in the presence of anti-β2GPI antibodies is explored, as well as the intracellular pathways via which this activation occurs. The relevance of these findings to understanding APS pathogenesis, in particular thrombosis, is discussed. The fifth chapter delineates the interaction between the fifth domain of β2GPI and FXI and its activated form factor XIa (FXIa). The ability of FXIa to cleave β2GPI between lysine (Lys) 317 and threonine (Thr) 318, and modulate its function is reported. The sixth chapter describes the ability of β2GPI to inhibit FXIa autoproteolytic hydrolysis at the specific FXIa residues arginine (Arg) 507, Arg532 and Lys539. This interaction with β2GPI stabilizes FXIa activity over time, and leads to enhanced FXIa mediated fibrin formation. This is a novel physiological function of β2GPI with important implications. Recent epidemiological studies by others have emphasized the critical role of FXIa in pathological thrombus propagation. The seventh chapter defines the relevance of the FXIa residues Arg507, Arg532 and Lys539 to FXIa mediated inactivation by the main FXIa inhibitor Protease Nexin 2 (PN2), and by Antithrombin III (ATIII). Insights into future directions for research are presented and discussed within each individual chapter.

An outline of the work contained in this thesis is presented. The first chapter is a critical review of the literature pertaining to the pathophysiological mechanisms operational with regards to the antiphospholipid syndrome (APS). The syndrome is characterised by venous and arterial thrombosis, and recurrent fetal loss, in association with the persistent presence of antibodies targeting the main autoantigen beta 2-glycoprotein I (β2GPI). The second chapter reviews the literature delineating the diverse physiological functions of β2GPI, and then relates them to its role in our current understanding of the pathophysiology of APS. The third chapter presents a critical review of the evidence base for the diagnosis and management of APS. The fourth chapter describes the interaction between β2GPI and the glycoprotein Ib alpha (GPIbα) subunit of the platelet receptor GPIb-IX-V. GPIbα is an important platelet adhesion receptor, which mediates multiple additional functions on the platelet surface, including binding coagulation factor XI (FXI). The implication of the interaction between β2GPI and GPIbα on platelet activation and the release of thromboxane in the presence of anti-β2GPI antibodies is explored, as well as the intracellular pathways via which this activation occurs. The relevance of these findings to understanding APS pathogenesis, in particular thrombosis, is discussed. The fifth chapter delineates the interaction between the fifth domain of β2GPI and FXI and its activated form factor XIa (FXIa). The ability of FXIa to cleave β2GPI between lysine (Lys) 317 and threonine (Thr) 318, and modulate its function is reported. The sixth chapter describes the ability of β2GPI to inhibit FXIa autoproteolytic hydrolysis at the specific FXIa residues arginine (Arg) 507, Arg532 and Lys539. This interaction with β2GPI stabilizes FXIa activity over time, and leads to enhanced FXIa mediated fibrin formation. This is a novel physiological function of β2GPI with important implications. Recent epidemiological studies by others have emphasized the critical role of FXIa in pathological thrombus propagation. The seventh chapter defines the relevance of the FXIa residues Arg507, Arg532 and Lys539 to FXIa mediated inactivation by the main FXIa inhibitor Protease Nexin 2 (PN2), and by Antithrombin III (ATIII). Insights into future directions for research are presented and discussed within each individual chapter.

No description available.

ABSTRACT OBJECTIVE: To determine the prevalence and clinical correlates of anti-phospholipid antibodies (aPL), including anti-cardiolipin antibodies (aCL), lupus anti-coagulant (LA), anti- β2-glycoprotein 1 (aβ2GP1) and anti-prothrombin (aPT) antibodies, in Black South African patients with systemic lupus erythematosus (SLE) METHODS: A cross-sectional study of 100 SLE patients in whom clinical characteristics, including features of the anti-phospholipid syndrome (APS), disease activity, and damage were documented, and sera tested for aCL, aβ2GP, and aPT of all isotypes, and LA. RESULTS: Positive aCL, aβ2GP1 and aPT and LA were found in 53, 84, 20, and 2 patients, respectively. Immunoglobulin (Ig)A aCL and IgG aβ2GP1 were the commonest aCL (49.1%) and aβ2GP1 (47%) isotypes, respectively. IgA aβ2GP1 were associated with both a history of thrombosis alone (p<0.05) and a history of any clinical feature, thrombosis and/or spontaneous abortion of the APS (p<0.05); IgA aCL were associated with a history of any clinical APS event (p<0.05); and aβ2GPI of any isotype were associated with a history of arthritis (p<0.001). CONCLUSION: My findings provide further evidence that the screening for aβ2GP1 and IgA aCL isotype may improve the risk assessment for APS in SLE patients of African extraction. Further prospective studies are warranted to determine the clinical utility of these tests and to elucidate the genetic basis for increased IgA aPL response in SLE patients of African extraction.

Thesis (Ph. D.)--University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Includes bibliographical references (p. 116-135).

No description available.

Anti-Beta2-Glycoprotein I antibodies (anti-b2GPI) are strongly associated with thrombosis in patients with primary antiphospholipid syndrome (PAPS). Anti-b2GPI activate endothelial cells (EC) resulting in a pro-thrombotic and pro-inflammatory phenotype. In order to characterise EC gene regulation in response to anti-b2GPI, early global gene expression was assessed in human umbilical vein endothelial cells (HUVEC) in response to affinity purified anti-b2GPI. Sera were collected from patients with PAPS and IgG was purified using HiTrap Protein G Sepharose columns. Polyclonal anti-b2GPI were prepared by passing patient IgG through NHS activated sepharose coupled to human b2GPI. Anti-b2GPI preparations were characterized by confirming their b2GPI co-factor dependence, binding to b2GPI and ability to induce leukocyte adhesion molecule expression and IL-8 production in vitro. Two microarray experiments tested differential global gene expression in 6 individual HUVEC donors in response to 5 different PAPS polyclonal anti-b2GPI (50 mg/ml) compared to 5 normal control IgG (50 mg/ml) after 4 hours incubation . Total HUVEC RNA was extracted and cRNA was prepared and hybridised to Affymetrix HG-133A (Exp.1) and HG-133A_2 (Exp.2) gene chips. Data were analyzed using a combination of the MAS 5.0 (Affymetrix) and GeneSpring (Agilent) software programmes. Significant change in gene expression was defined as greater than two fold increase or decrease in expression (p<0.05). Novel genes not previously associated with PAPS were induced including chemokines CCL20, CXCL3, CX3CL1, CXCL5, CXCL2 and CXCL1, the receptors Tenascin C, OLR1, IL-18 receptor 1 and growth factors, CSF2, CSF3, IL-6, IL1b and FGF18. Downregulated genes were transcription factors/signaling molecules including ID2. Microarray results were confirmed for selected genes (CSF3, CX3CL1, FGF18, ID2, SOD2, Tenascin C) using quantitative real-time RT-PCR analysis. This study revealed a complex anti-b2GPI-regulated gene expression profile in HUVEC in vitro. The novel chemokines and pro-inflammatory cytokines identified in this study may contribute to the vasculopathy associated with PAPS.

Bakgrund: Eculizumab (Solirisâ) är en monoklonal antikropp som är riktad mot C5 i komplementsystemet. Bindning av eculizumab till C5 förhindrar proteinets klyvning och därmed också aktivering. Eculizumab är godkänt för behandling av atypiskt hemolytiskt uremiskt syndrom och paroxysmal nokturn hemoglobinuri. Sedan behandlingen blivit godkänd för dessa tillstånd har även ”off-label use” vid andra tillstånd varit betydande. En tidigare studie har visat att uppemot 50 % av behandling med eculizumab är off-label use, det vill säga behandling utanför de idag godkända indikationerna. Ett av dessa tillstånd är katastrofalt antifosfolipidsyndrom (KAPS), ett mycket allvarligt tillstånd som karaktäriseras av multipla tromboser som utvecklas under kort tid i flera organ vid vilket eculizumab visat sig ha en potentiellt positiv effekt. KAPS kan uppstå om man har bakomliggande antifosfolipid syndrom (APS) och kan utlösas vid en så kallad ”second hit”, en inflammatorisk stressreaktion orsakad av exempelvis en infektion eller kirurgiskt ingrepp. Eculizumab är ett särläkemedel och är en av de dyraste läkemedelsbehandlingarna i världen. Syfte: Syftet med denna studie var att analysera fall där KAPS behandlats med eculizumab för att utvärdera om eculizumab bör vara standarbehandling vid detta tillstånd. Likheter och olikheter mellan fallen studerades för att utvärdera när det kan vara lämpligt att behandla med eculizumab. Syftet var också att utvärdera detta utifrån ett ekonomiskt perspektiv. Metod: Detta är en litteraturstudie där sökningar i PubMed gjorts efter rapporter som beskriver fall där patienter med KAPS eller som ansetts haft en risk att utveckla KAPS behandlats med eculizumab. Åtta rapporter med totalt tio fall inkluderades och analyserades. Resultat: De rapporter som analyserades visade övergripande en tydlig effekt av behandling med eculizumab. Eculizumab tolkades också i vissa fall som ett kostnadseffektivt alternativ genom bland annat förkortad intensivvård och dialysbehov. Slutsats: Eculizumab har i de fall som analyserats visat sig ha en avgörande betydelse för att reversera ett livshotande tillstånd och skulle kunna vara standardbehandling vid KAPS och förebyggande av KAPS. För att eculizumab, eller en annan komplementhämmare, ska kunna bli standardbehandling krävs ytterligare forskning på KAPS och dess relation till komplementsystemet. / Catastrophic antiphospholipidsyndrome (CAPS) is a rare but highly fatal condition characterized by thrombosis in multiple organs, often associated with a rapid progression of disease and serious complications for the patient. A rapid diagnosis and treatment is therefore a key to manage this condition. The conventional treatment, which consists of anticoagulation, steroids, plasma exchange and intravenous immunoglobulins, reduces mortality but CAPS is still associated with high mortality. To find the mechanism of how and why this condition evolves is therefore important. There has been progress to find out the pathogenesis and one clue appears to be the complement system. Therefore, a new type of treatment has been used in patients who have been diagnosed with antiphosphlipidsyndrome (APS) and have had a risk of developing CAPS, or have been diagnosed with definitive or probable CAPS. This treatment is aimed at inhibiting parts of the complement system and consists of a monoclonal antibody called eculizumab. Lately eculizumab has been used off label in patients diagnosed with CAPS and in patients that has been at risk of developing CAPS. The results of this treatment have been positive and have therefore been considered as a possible alternative for treating CAPS. The aim of this study was to evaluate if eculizumab can be an alternative to treat patients with CAPS and patients diagnosed with APS who have a risk of developing CAPS. In order to evaluate treatment with eculizumab in patients with CAPS, searches on cases were done in the database PubMed for reports of patients with CAPS or at risk of developing CAPS who have been treated with eculizumab. Eight reports with a total of ten cases were found and used in order to answer the hypothesis of this study. In the ten cases that were analyzed there was a clear connection between the treatment and the recovery. In both patients with CAPS and patients at risk of developing CAPS the treatment with eculizumab was considered of significant importance. Because of the rarity of this condition, every case makes significant impact into the understanding of this potentially fatal condition. For future new cases, the present report will stand as an important source for making decisions about treatment with eculizumab. With time and more cases with positive results eculizumab has the potential to become conventional treatment for CAPS.

Hypermetabolism, observed in Sydenham's chorea (SC); a complication of acute rheumatoid fever (ARF) involving binding of streptococcal M protein antibodies in the brain, may result from an increase in glutamate release. The interaction of mAb 1 OF5, a specific M protein antibody subtype, with brain proteins (e.g. Rabphilin-3A), synaptic vesicles (SVs) and synaptosomal fraction (SF) was examined. Rat brain slices immunostained with mAb l OF5 revealed an interaction with choroid plexus and elements appearing to be neuropils. Dot blotting demonstrated an interaction of mAb I OF5 with both SVs and SFs. Western blotting revealed a smear from mAb 10F5 against the SF fraction. However, both modified SVs and pure liposomes examined by fluorescent and confocal microscopy bound mAbl0F5 suggesting a direct interaction with phospholipids. ELISA demonstrated binding of mAb1OF5 with negatively charged phospholipids involved in antiphospholipid syndrome (APS). Hypermetabolism and binding at the choroid plexus is observed in SC and APS supporting the connection between these disorders. / Department of Physiology and Health Science