B. Giannakopoulos - Academia.edu (original) (raw)
Papers by B. Giannakopoulos
Thrombosis Journal, 2016
The antiphospholipid syndrome (APS) is an autoimmune disease characterised by a procoagulant stat... more The antiphospholipid syndrome (APS) is an autoimmune disease characterised by a procoagulant state that predisposes to recurrent thrombosis and miscarriages. Two major discoveries have advanced our understanding of the underlying complex pathogenesis of the APS. The first was the discovery that beta-2 glycoprotein-1 (β2GPI) is the major auto antigen in APS. The second was the discovery in more recent years that β2GPI contains allosteric disulphide bonds susceptible to posttranslational modification that may be involved in the development of autoantibodies in APS. The main allosteric disulphide bond in the fifth domain of β2GPI can exist in two redox states: free thiol or oxidised. It is the conformational transformation of β2GPI from its free thiol form to its more immunogenic oxidised form that exposes neo-epitopes on the first and fifth domains. The purpose of this review is to highlight the recent findings on the posttranslational forms of β2GPI in the pathogenesis of APS. We suggest that novel assays quantitating the different redox forms of β2GPI in plasma or serum may be used to supplement existing clinical and laboratory assays to more accurately stratify risk of thrombosis or miscarriage in APS patients.
Scientific reports, Jan 15, 2017
The immune responses of males and females to bacterial infections display differences. The mechan... more The immune responses of males and females to bacterial infections display differences. The mechanisms that underlie this sexual dimorphism are multifactorial. Lipopolysaccharide (LPS) contributes to the pathogenesis of endotoxaemia. We have previously demonstrated that the plasma protein beta-2 glycoprotein-1 (β2GPI) reduces LPS-induced inflammation in male mice. In the present study using a more robust infection model of septicaemia the role of β2GPI is examined in both male and female wild type (WT) and β2GPI deficient (β2GPI(-/-)) mice challenged with Escherichia coli (E. coli) intravenously. β2GPI deficiency led to an increase of E. coli colony forming units (CFU) in the circulation of both male and female mice. In male β2GPI(-/-) mice this was associated with a worse clinical severity score. This difference was not observed between female β2GPI(-/-) and female WT mice. Male WT mice had decreased levels of total and increased levels of free thiol β2GPI following administration o...
J Thromb Haemost. 2010 Aug;8(8):1754-62. doi: 10.1111/j.1538-7836.2010.03944.x.Redox control of â... more J Thromb Haemost. 2010 Aug;8(8):1754-62. doi: 10.1111/j.1538-7836.2010.03944.x.Redox control of â2-glycoprotein I-von Willebrand factor interaction by thioredoxin-1.Passam FH, Rahgozar S, Qi M, Raftery MJ, Wong JW, Tanaka K, Ioannou Y, Zhang JY, Gemmell R, Qi JC, Giannakopoulos B, Hughes WE, Hogg PJ, Krilis SA.Department of Immunology, Allergy and Infectious Diseases, University of New South Wales, St George Hospital, Sydney, Australia.AbstractBACKGROUND: â(2) -Glycoprotein I (â(2) GPI) is an abundant plasma protein that is closely linked to blood clotting, as it interacts with various protein and cellular components of the coagulation system. However, the role of â(2) GPI in thrombus formation is unknown. We have recently shown that â(2) GPI is susceptible to reduction by the thiol oxidoreductases thioredoxin-1 and protein disulfide isomerase, and that reduction of â(2) GPI can take place on the platelet surface.METHODS: â(2) GPI, reduced by thioredoxin-1, was labeled...
An outline of the work contained in this thesis is presented. The first chapter is a critical rev... more 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 func...
PloS one, 2016
Reperfusion after a period of ischemia results in reperfusion injury (IRI) which involves activat... more Reperfusion after a period of ischemia results in reperfusion injury (IRI) which involves activation of the inflammatory cascade. In cardiac IRI, IgM natural antibodies (NAb) play a prominent role through binding to altered neoepitopes expressed on damaged cells. Beta 2 Glycoprotein I (β2GPI) is a plasma protein that binds to neoepitopes on damaged cells including anionic phospholipids through its highly conserved Domain V. Domain I of β2GPI binds circulating IgM NAbs and may provide a link between the innate immune system, IgM NAb binding and cardiac IRI. This study was undertaken to investigate the role of Β2GPI and its Domain V in cardiac IRI using wild-type (WT), Rag-1 -/- and β2GPI deficient mice. Compared with control, treatment with Domain V prior to cardiac IRI prevented binding of endogenous β2GPI to post-ischemic myocardium and resulted in smaller myocardial infarction size in both WT and β2GPI deficient mice. Domain V treatment in WT mice also resulted in less neutrophil ...
Methods in Molecular Biology, 2019
Angiotensinogen mediates an important role in the pathophysiology of preeclampsia, a disorder of ... more Angiotensinogen mediates an important role in the pathophysiology of preeclampsia, a disorder of pregnancy characterized by hypertension and proteinuria usually after 20 weeks of gestation. Angiotensinogen is found in two distinct posttranslational forms in the plasma, an oxidized and a reduced (free thiol) form. Higher levels of the oxidized form are associated with an increased risk of preeclampsia. We have developed novel ELISA assays to quantitate the levels of total and free thiol angiotensinogen allowing for calculation of the amount of oxidized angiotensinogen species. We describe the methodology for performing these assays.
Internal Medicine Journal, 2017
L.Adams M.Adams P.Adamson L.Afrin W.Ahmar C.Ajaero A.Ajani C.Akin S.Aldous D.Allen D.Ames A.Anazo... more L.Adams M.Adams P.Adamson L.Afrin W.Ahmar C.Ajaero A.Ajani C.Akin S.Aldous D.Allen D.Ames A.Anazodo N.Anderson J.Andrews P.Angchaisuksiri P.Angus M.Anpalahan G.Arendts L.Arnheim-Dahlstrom A.Artero D.Askew M.Asrar ul Haq J.Atherton E.Atkins V.Atkinson J.Attia K.Auret M.Avent A.Aydogdu B.Ayres P.Badenoch T.Badrick W.Bagg A.Bajel B.Baker R.Baker D.Balakrishnan P.Bardin D.Barnes M.Barras J.Begun C.Bennett L.Berkahn N.Bett A.Bianchi T.Blackmore A.Blyth S.Bohlander L.Bolitho R.Boots M.Boughey J.Bourcier N.Bowden S.Bowler G.Braatvedt H.Brodaty P.Brooks N.Buckley K.Buising A.Butler D.Campbell P.Campbell G.Caplan S.Carney A.Catanchin F.Chahadi S.Chambers C.Chan G.Chan N.Chan R.Charlewood J.Chay T.Chemmanam D.Chipps K.Chow T.Christmas E.Chua F.Chung D.Clark K.Clark R.Climie PS.Coates PT.Coates B.Cochrane A.Cohen S.Cohney D.Cole L.Cole M.Collins P.Colman W.Connell S.Connor I.Cook J.Cook C.Cooper M.Cooper G.Corbett S.Corcoran T.Cox N.Cranswick D.Crawford G.Crawford K.Crosier B.Crotty I.Crozier K.Cuff G.Cull B.Cunha J.Curnow E.Dabscheck H.Davies B.Day R.Day T.Day P.De Cruz C.De Pasquale J.Dean G.Deed A.Delaney A.Demirkol J.Denholm E.Dent E.Denton B.Depczynski M.Deuble B.Devitt G.Devlin H.Dewey X.Diao M.Dickinson M.Doogue J.Douglass F.Doukas P.Drennan J.D’Rozario G.Duke E.Duncan A.Duncombe A.Dunlop T.Dunning J.Dunuwille D.Dwyer J.Dyer N.Eaddy O.Ed P.Edmonds D.Eisen E.Ekinci K.Ellard T.Ewer N.Ezard F.Fahrtash M.Fanning S.Faux P.Ferrari D.Fielding R.Filshie J.Fink P.Fitzharris P.Flanagan M.Flannery S.Fleming K.Fong M.Forbes A.Foy R.Francis B.Freedman A.Fu L.Gagliardi A.Gaitatzis K.Ganda P.Ganly S.Garland D.Garofalo R.Garsia P.Gatenby M.George D.Ghia B.Giannakopoulos H.Gibbs C.Gillebert L.Glenn G.Gobe M.Gold B.Goswami R.Goucke L.Gray K.Greaves
Systemic Lupus Erythematosus, 2007
Lupus, 2012
AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) ... more AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) is the first-ever international research network that has been created specifically to design and conduct well-designed, large-scale, multi-center clinical trials in persistently antiphospholipid antibody (aPL)-positive patients. The founding principle of the APS ACTION is that it is an internationally collaborative effort, open to qualified investigators across the globe who are committed to furthering our understanding of APS and its management. Due to the hard work and collaborative spirit of APS ACTION members, in early 2012, APS ACTION launched two important collaborative international projects: 1) a randomized controlled trial of hydroxychloroquine in the primary thrombosis prevention of persistently aPL-positive but thrombosis-free patients without other systemic autoimmune diseases; and 2) a web-based registry of aPL-positive patients with or without systemic autoimmune diseases,...
Arthritis & Rheumatism, 2009
The autoantigens 60-kd Ro/SSA (Ro 60) and beta(2)-glycoprotein I (beta(2)GPI) are both displayed ... more The autoantigens 60-kd Ro/SSA (Ro 60) and beta(2)-glycoprotein I (beta(2)GPI) are both displayed on the surface membrane of apoptotic cells. Epitope-spreading experiments have suggested that these autoantigens may be present as a complex on the apoptotic cell surface. This study was undertaken to investigate whether beta(2)GPI interacts with Ro 60 on apoptotic cells and alters the binding of anti-Ro 60 IgG. The interaction between soluble recombinant Ro 60 fragments and beta(2)GPI was investigated in vitro by direct and saturation binding assays using native human beta(2)GPI and recombinant domain deletion mutants. Binding of beta(2)GPI to early and late apoptotic cells was assessed by multiparameter flow cytometry, and specificity of binding was determined by competitive inhibition with soluble recombinant Ro 60 and anti-Ro 60 IgG. The Ro 60 fragment expressing a surface-exposed epitope (apotope) bound with high affinity (K(d) = approximately 15 nM) to domain V of beta(2)GPI in vitro. Beta(2)-glycoprotein I bound to the surface of apoptotic cells in a dose-dependent manner and was blocked by the Ro 60 apotope fragment. In reciprocal competitive inhibition studies, beta(2)GPI blocked the binding of anti-Ro 60 autoantibodies to apoptotic cells in a dose-dependent manner, and anti-Ro 60 IgG inhibited the binding of beta(2)GPI. Moreover, beta(2)GPI showed a 2-fold increase in binding to apoptotic cells that overexpress Ro 60 on the surface. These results demonstrate that Ro 60 functions as a novel receptor for beta(2)GPI on the surface of apoptotic cells. The formation of Ro 60-beta(2)GPI complexes may protect against anti-Ro 60 autoantibody-mediated tissue injury.
Current rheumatology reports, 2011
β2-glycoprotein I (β2GPI) is the major autoantigen in the antiphospholipid syndrome. The central ... more β2-glycoprotein I (β2GPI) is the major autoantigen in the antiphospholipid syndrome. The central importance of understanding β2GPI physiology from the perspective of the rheumatologist is that it forms the foundation for understanding the pathophysiology underlying autoantibody generation, and the diverse mechanisms by which anti-β2GPI antibodies in complex with β2GPI may predispose an individual to the antiphospholipid syndrome clinical phenotype. This review examines some of the latest novel findings in this area.
Β2-Glycoprotein I (β2GPI) is an important anti-thrombotic protein and is the major auto-antigen i... more Β2-Glycoprotein I (β2GPI) is an important anti-thrombotic protein and is the major auto-antigen in the antiphospholipid syndrome (APS). The clinical relevance of nitrosative stress in post translational modification of β2GPI was examined.The effects of nitrated (n)β2GPI on its anti-thrombotic properties and its plasma levels in primary and secondary APS were determined with appropriate clinical control groups. β2-glycoprotein I was nitrated at tyrosines 218, 275 and 309. β2-glycoprotein I binds to lipid peroxidation modified products through Domains IV and V. Nitrated β2GPI loses this binding (p < 0.05) and had diminished activity in inhibiting platelet adhesion to vWF under high shear flow (p < 0.01). Levels of nβ2GPI were increased in patients with primary APS compared to patients with either secondary APS (p < 0.05), autoimmune disease without APS (p < 0.05) or non-autoimmune patients with arterial thrombosis (p < 0.01) and healthy individuals (p < 0.05).In conc...
Arthritis & Rheumatology, 2014
The BXSB.Yaa mouse strain is a model of systemic lupus erythematosus that is dependent on duplica... more The BXSB.Yaa mouse strain is a model of systemic lupus erythematosus that is dependent on duplication of the Toll-like receptor 7 gene. The objective of this study was to systematically describe the amplified autoimmune phenotype observed when the soluble plasma protein β2 -glycoprotein I (β2 GPI) gene was deleted in male BXSB.Yaa mice. We generated BXSB.Yaa and NZW mouse strains in which the β2 GPI gene had been knocked out by backcrossing the wild-type strains with C57BL/6 β2 GPI(-/-) mice for 10 generations. Sex- and age-matched mice of the various strains were housed under identical conditions and were killed at fixed time intervals. Serum and tissue specimens were collected at various time points. Lupus-associated autoantibodies, inflammatory cytokines, and the type I interferon (IFN) gene signature were measured. Flow cytometric analyses of lymphocyte populations were performed. The severity of glomerulonephritis was graded by 2 independent renal histopathologists. Male BXSB.Yaa β2 GPI(-/-) mice developed significant lymphadenopathy and splenomegaly compared with age-matched controls. Male BXSB.Yaa β2 GPI(-/-) mice also had significantly higher levels of autoantibodies, increased levels of inflammatory cytokines including tumor necrosis factor α, interleukin-6, and BAFF, and more severe glomerulonephritis. The type I IFN gene signature in male BXSB.Yaa β2 GPI(-/-) mice was significantly higher than that in control mice. Male BXSB.Yaa β2 GPI(-/-) mice also had marked dysregulation of various B cell and T cell populations in the spleens and lymph nodes and a disturbance in apoptotic cell clearance. Deletion of β2 GPI accelerates and potentiates the autoimmune phenotype in male BXSB.Yaa mice.
Heart, Lung and Circulation
PLOS ONE, 2015
Objective Angiotensinogen exists in two distinct redox forms in plasma, the oxidized sulfhydryl-b... more Objective Angiotensinogen exists in two distinct redox forms in plasma, the oxidized sulfhydryl-bridge form and the reduced, unbridged, free thiol form. The oxidized form of angiotensinogen compared to the free thiol form preferentially interacts with renin resulting in increased generation of angiotensin. The predictive potential of the ratio of free-thiol to oxidized angiotensinogen in the plasma for pre-eclampsia was first suggested by the Read group in ref 10. We propose an improved method for determining the ratio and validate the method in a larger cohort of pregnant women.
Antioxidants & redox signaling, 2015
Age-related macular degeneration (AMD) affects the region of the retina responsible for high reso... more Age-related macular degeneration (AMD) affects the region of the retina responsible for high resolution vision. It is a major cause of blindness in the ageing population. This is the first study to examine the association of redox modified, cysteine based, post-translational forms of beta 2-glycoprotein I (β2GPI) in the plasma of individuals with early and late stages of patients with AMD compared to controls. Exploration is also undertaken to assess whether the free thiol form of β2GPI versus the oxidized disulfide form have distinct functional properties in the setting of hydrogen peroxide mediated cell death of an immortalized human retinal pigment epithelium (RPE) cell line. We demonstrate β2GPI in the retina and choroid of patients with AMD. Free thiol β2GPI is shown to protect the immortalized human RPE cell line against H2O2 induced cell death, whereas the oxidized form of β2GPI and free thiol bovine serum albumin were not protective. Free thiol β2GPI levels were significantl...
Hematology, 2014
This chapter reviews several important themes pertaining to the antiphospholipid syndrome (APS), ... more This chapter reviews several important themes pertaining to the antiphospholipid syndrome (APS), including a description of the clinical features, a discussion of the main autoantigen, beta 2-glycoprotein I (β2GPI), and insights into the characteristics of the pathogenic anti-β2GPI autoantibodies. Evidence-based considerations for when to test for APS are explored, along with the clinical significance of patients testing positive on multiple APS assays, so-called triple positivity. A detailed review of recently published laboratory guidelines for the detection of lupus anticoagulant and the solid-phase anticardiolipin and anti-β2GPI ELISAs is undertaken. Finally, a brief review of nonclassification criteria laboratory assays with potential future diagnostic utility is presented.
Thrombosis Research, 2004
Beta-2 glycoprotein I (β2GPI) is the principal target of autoantibodies in the antiphospholipid s... more Beta-2 glycoprotein I (β2GPI) is the principal target of autoantibodies in the antiphospholipid syndrome (APS). It is abundant in human plasma and shares high homology between different mammalian species. Although the exact physiological function of β2GPI has not been fully elucidated, several interactions have been described with other proteins and with negatively charged surfaces, such as anionic phospholipids, dextran and heparin. β2GPI is involved in the coagulation pathway, exerting both procoagulant and anticoagulant activities. Plasma from β2GPI-deficient mice exhibits impaired thrombin generation in vitro. Recently, it has been demonstrated that β2GPI binds factor (F) XI in vitro at concentrations lower than those of the protein in human plasma, and this binding inhibits FXI activation to FXIa by thrombin and FXIIa. Proteolytic cleavage of the fifth domain of β2GPI abolishes its inhibition of FXI activation and results in reduced ability of the cleaved β2GPI to bind phospholipids. It retains its ability to bind FXI. In vivo activation of FXI by thrombin is thought to be an important mechanism by which coagulation is accelerated via components of the contact activation pathway. Thus β2GPI may attenuate the contact activation pathway by inhibiting activation of FXI by thrombin. Moreover, because β2GPI is the dominant autoantigen in patients with APS, dysregulation of this pathway by autoantibodies may be an important mechanism for thrombosis in patients with APS.
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](Rheumatology, 2010
ANCA antibodies were negative. Polyclonal increase in gamma globulins. A diagnosis of primary Sjö... more ANCA antibodies were negative. Polyclonal increase in gamma globulins. A diagnosis of primary Sjö gren's syndrome was made. Case 3: A 66 year old female with an established diagnosis of Sjö gren's syndrome presented with breathlessness. Hitherto her chief symptoms had been xerostomia with episodic salivary gland swelling. She was known to have positive ANA, anti-SSA, anti-SSB and cardiolipin antibodies, as well as rheumatoid factor. A salivary gland biopsy had demonstrated changes consistent with Sjö gren's syndrome. Chest CT showed a number of uniform thin-walled cysts evenly scattered throughout both lungs, with subtle subpleural interstitial changes only and no pulmonary infiltrate. Conclusions: Estimates of the frequency of lung cysts in primary Sjö gren's range from 8 to 46%. However, in most reports cysts are described in conjunction with ground glass changes and bronchiectasis; these two are generally viewed as the most typical lung changes in Sjö gren's syndrome. However, our experience suggests that cystic disease as the predominant lung finding in Sjö gren's is not uncommon. Moreover, as these cases demonstrate, the presence of cysts can assist both in making the diagnosis (case 1) and in differentiating Sjö gren's from other connective tissue diseases (case 2). Primary Sjö gren's syndrome should be considered when cystic lung disease is found.
Thrombosis Journal, 2016
The antiphospholipid syndrome (APS) is an autoimmune disease characterised by a procoagulant stat... more The antiphospholipid syndrome (APS) is an autoimmune disease characterised by a procoagulant state that predisposes to recurrent thrombosis and miscarriages. Two major discoveries have advanced our understanding of the underlying complex pathogenesis of the APS. The first was the discovery that beta-2 glycoprotein-1 (β2GPI) is the major auto antigen in APS. The second was the discovery in more recent years that β2GPI contains allosteric disulphide bonds susceptible to posttranslational modification that may be involved in the development of autoantibodies in APS. The main allosteric disulphide bond in the fifth domain of β2GPI can exist in two redox states: free thiol or oxidised. It is the conformational transformation of β2GPI from its free thiol form to its more immunogenic oxidised form that exposes neo-epitopes on the first and fifth domains. The purpose of this review is to highlight the recent findings on the posttranslational forms of β2GPI in the pathogenesis of APS. We suggest that novel assays quantitating the different redox forms of β2GPI in plasma or serum may be used to supplement existing clinical and laboratory assays to more accurately stratify risk of thrombosis or miscarriage in APS patients.
Scientific reports, Jan 15, 2017
The immune responses of males and females to bacterial infections display differences. The mechan... more The immune responses of males and females to bacterial infections display differences. The mechanisms that underlie this sexual dimorphism are multifactorial. Lipopolysaccharide (LPS) contributes to the pathogenesis of endotoxaemia. We have previously demonstrated that the plasma protein beta-2 glycoprotein-1 (β2GPI) reduces LPS-induced inflammation in male mice. In the present study using a more robust infection model of septicaemia the role of β2GPI is examined in both male and female wild type (WT) and β2GPI deficient (β2GPI(-/-)) mice challenged with Escherichia coli (E. coli) intravenously. β2GPI deficiency led to an increase of E. coli colony forming units (CFU) in the circulation of both male and female mice. In male β2GPI(-/-) mice this was associated with a worse clinical severity score. This difference was not observed between female β2GPI(-/-) and female WT mice. Male WT mice had decreased levels of total and increased levels of free thiol β2GPI following administration o...
J Thromb Haemost. 2010 Aug;8(8):1754-62. doi: 10.1111/j.1538-7836.2010.03944.x.Redox control of â... more J Thromb Haemost. 2010 Aug;8(8):1754-62. doi: 10.1111/j.1538-7836.2010.03944.x.Redox control of â2-glycoprotein I-von Willebrand factor interaction by thioredoxin-1.Passam FH, Rahgozar S, Qi M, Raftery MJ, Wong JW, Tanaka K, Ioannou Y, Zhang JY, Gemmell R, Qi JC, Giannakopoulos B, Hughes WE, Hogg PJ, Krilis SA.Department of Immunology, Allergy and Infectious Diseases, University of New South Wales, St George Hospital, Sydney, Australia.AbstractBACKGROUND: â(2) -Glycoprotein I (â(2) GPI) is an abundant plasma protein that is closely linked to blood clotting, as it interacts with various protein and cellular components of the coagulation system. However, the role of â(2) GPI in thrombus formation is unknown. We have recently shown that â(2) GPI is susceptible to reduction by the thiol oxidoreductases thioredoxin-1 and protein disulfide isomerase, and that reduction of â(2) GPI can take place on the platelet surface.METHODS: â(2) GPI, reduced by thioredoxin-1, was labeled...
An outline of the work contained in this thesis is presented. The first chapter is a critical rev... more 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 func...
PloS one, 2016
Reperfusion after a period of ischemia results in reperfusion injury (IRI) which involves activat... more Reperfusion after a period of ischemia results in reperfusion injury (IRI) which involves activation of the inflammatory cascade. In cardiac IRI, IgM natural antibodies (NAb) play a prominent role through binding to altered neoepitopes expressed on damaged cells. Beta 2 Glycoprotein I (β2GPI) is a plasma protein that binds to neoepitopes on damaged cells including anionic phospholipids through its highly conserved Domain V. Domain I of β2GPI binds circulating IgM NAbs and may provide a link between the innate immune system, IgM NAb binding and cardiac IRI. This study was undertaken to investigate the role of Β2GPI and its Domain V in cardiac IRI using wild-type (WT), Rag-1 -/- and β2GPI deficient mice. Compared with control, treatment with Domain V prior to cardiac IRI prevented binding of endogenous β2GPI to post-ischemic myocardium and resulted in smaller myocardial infarction size in both WT and β2GPI deficient mice. Domain V treatment in WT mice also resulted in less neutrophil ...
Methods in Molecular Biology, 2019
Angiotensinogen mediates an important role in the pathophysiology of preeclampsia, a disorder of ... more Angiotensinogen mediates an important role in the pathophysiology of preeclampsia, a disorder of pregnancy characterized by hypertension and proteinuria usually after 20 weeks of gestation. Angiotensinogen is found in two distinct posttranslational forms in the plasma, an oxidized and a reduced (free thiol) form. Higher levels of the oxidized form are associated with an increased risk of preeclampsia. We have developed novel ELISA assays to quantitate the levels of total and free thiol angiotensinogen allowing for calculation of the amount of oxidized angiotensinogen species. We describe the methodology for performing these assays.
Internal Medicine Journal, 2017
L.Adams M.Adams P.Adamson L.Afrin W.Ahmar C.Ajaero A.Ajani C.Akin S.Aldous D.Allen D.Ames A.Anazo... more L.Adams M.Adams P.Adamson L.Afrin W.Ahmar C.Ajaero A.Ajani C.Akin S.Aldous D.Allen D.Ames A.Anazodo N.Anderson J.Andrews P.Angchaisuksiri P.Angus M.Anpalahan G.Arendts L.Arnheim-Dahlstrom A.Artero D.Askew M.Asrar ul Haq J.Atherton E.Atkins V.Atkinson J.Attia K.Auret M.Avent A.Aydogdu B.Ayres P.Badenoch T.Badrick W.Bagg A.Bajel B.Baker R.Baker D.Balakrishnan P.Bardin D.Barnes M.Barras J.Begun C.Bennett L.Berkahn N.Bett A.Bianchi T.Blackmore A.Blyth S.Bohlander L.Bolitho R.Boots M.Boughey J.Bourcier N.Bowden S.Bowler G.Braatvedt H.Brodaty P.Brooks N.Buckley K.Buising A.Butler D.Campbell P.Campbell G.Caplan S.Carney A.Catanchin F.Chahadi S.Chambers C.Chan G.Chan N.Chan R.Charlewood J.Chay T.Chemmanam D.Chipps K.Chow T.Christmas E.Chua F.Chung D.Clark K.Clark R.Climie PS.Coates PT.Coates B.Cochrane A.Cohen S.Cohney D.Cole L.Cole M.Collins P.Colman W.Connell S.Connor I.Cook J.Cook C.Cooper M.Cooper G.Corbett S.Corcoran T.Cox N.Cranswick D.Crawford G.Crawford K.Crosier B.Crotty I.Crozier K.Cuff G.Cull B.Cunha J.Curnow E.Dabscheck H.Davies B.Day R.Day T.Day P.De Cruz C.De Pasquale J.Dean G.Deed A.Delaney A.Demirkol J.Denholm E.Dent E.Denton B.Depczynski M.Deuble B.Devitt G.Devlin H.Dewey X.Diao M.Dickinson M.Doogue J.Douglass F.Doukas P.Drennan J.D’Rozario G.Duke E.Duncan A.Duncombe A.Dunlop T.Dunning J.Dunuwille D.Dwyer J.Dyer N.Eaddy O.Ed P.Edmonds D.Eisen E.Ekinci K.Ellard T.Ewer N.Ezard F.Fahrtash M.Fanning S.Faux P.Ferrari D.Fielding R.Filshie J.Fink P.Fitzharris P.Flanagan M.Flannery S.Fleming K.Fong M.Forbes A.Foy R.Francis B.Freedman A.Fu L.Gagliardi A.Gaitatzis K.Ganda P.Ganly S.Garland D.Garofalo R.Garsia P.Gatenby M.George D.Ghia B.Giannakopoulos H.Gibbs C.Gillebert L.Glenn G.Gobe M.Gold B.Goswami R.Goucke L.Gray K.Greaves
Systemic Lupus Erythematosus, 2007
Lupus, 2012
AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) ... more AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) is the first-ever international research network that has been created specifically to design and conduct well-designed, large-scale, multi-center clinical trials in persistently antiphospholipid antibody (aPL)-positive patients. The founding principle of the APS ACTION is that it is an internationally collaborative effort, open to qualified investigators across the globe who are committed to furthering our understanding of APS and its management. Due to the hard work and collaborative spirit of APS ACTION members, in early 2012, APS ACTION launched two important collaborative international projects: 1) a randomized controlled trial of hydroxychloroquine in the primary thrombosis prevention of persistently aPL-positive but thrombosis-free patients without other systemic autoimmune diseases; and 2) a web-based registry of aPL-positive patients with or without systemic autoimmune diseases,...
Arthritis & Rheumatism, 2009
The autoantigens 60-kd Ro/SSA (Ro 60) and beta(2)-glycoprotein I (beta(2)GPI) are both displayed ... more The autoantigens 60-kd Ro/SSA (Ro 60) and beta(2)-glycoprotein I (beta(2)GPI) are both displayed on the surface membrane of apoptotic cells. Epitope-spreading experiments have suggested that these autoantigens may be present as a complex on the apoptotic cell surface. This study was undertaken to investigate whether beta(2)GPI interacts with Ro 60 on apoptotic cells and alters the binding of anti-Ro 60 IgG. The interaction between soluble recombinant Ro 60 fragments and beta(2)GPI was investigated in vitro by direct and saturation binding assays using native human beta(2)GPI and recombinant domain deletion mutants. Binding of beta(2)GPI to early and late apoptotic cells was assessed by multiparameter flow cytometry, and specificity of binding was determined by competitive inhibition with soluble recombinant Ro 60 and anti-Ro 60 IgG. The Ro 60 fragment expressing a surface-exposed epitope (apotope) bound with high affinity (K(d) = approximately 15 nM) to domain V of beta(2)GPI in vitro. Beta(2)-glycoprotein I bound to the surface of apoptotic cells in a dose-dependent manner and was blocked by the Ro 60 apotope fragment. In reciprocal competitive inhibition studies, beta(2)GPI blocked the binding of anti-Ro 60 autoantibodies to apoptotic cells in a dose-dependent manner, and anti-Ro 60 IgG inhibited the binding of beta(2)GPI. Moreover, beta(2)GPI showed a 2-fold increase in binding to apoptotic cells that overexpress Ro 60 on the surface. These results demonstrate that Ro 60 functions as a novel receptor for beta(2)GPI on the surface of apoptotic cells. The formation of Ro 60-beta(2)GPI complexes may protect against anti-Ro 60 autoantibody-mediated tissue injury.
Current rheumatology reports, 2011
β2-glycoprotein I (β2GPI) is the major autoantigen in the antiphospholipid syndrome. The central ... more β2-glycoprotein I (β2GPI) is the major autoantigen in the antiphospholipid syndrome. The central importance of understanding β2GPI physiology from the perspective of the rheumatologist is that it forms the foundation for understanding the pathophysiology underlying autoantibody generation, and the diverse mechanisms by which anti-β2GPI antibodies in complex with β2GPI may predispose an individual to the antiphospholipid syndrome clinical phenotype. This review examines some of the latest novel findings in this area.
Β2-Glycoprotein I (β2GPI) is an important anti-thrombotic protein and is the major auto-antigen i... more Β2-Glycoprotein I (β2GPI) is an important anti-thrombotic protein and is the major auto-antigen in the antiphospholipid syndrome (APS). The clinical relevance of nitrosative stress in post translational modification of β2GPI was examined.The effects of nitrated (n)β2GPI on its anti-thrombotic properties and its plasma levels in primary and secondary APS were determined with appropriate clinical control groups. β2-glycoprotein I was nitrated at tyrosines 218, 275 and 309. β2-glycoprotein I binds to lipid peroxidation modified products through Domains IV and V. Nitrated β2GPI loses this binding (p < 0.05) and had diminished activity in inhibiting platelet adhesion to vWF under high shear flow (p < 0.01). Levels of nβ2GPI were increased in patients with primary APS compared to patients with either secondary APS (p < 0.05), autoimmune disease without APS (p < 0.05) or non-autoimmune patients with arterial thrombosis (p < 0.01) and healthy individuals (p < 0.05).In conc...
Arthritis & Rheumatology, 2014
The BXSB.Yaa mouse strain is a model of systemic lupus erythematosus that is dependent on duplica... more The BXSB.Yaa mouse strain is a model of systemic lupus erythematosus that is dependent on duplication of the Toll-like receptor 7 gene. The objective of this study was to systematically describe the amplified autoimmune phenotype observed when the soluble plasma protein β2 -glycoprotein I (β2 GPI) gene was deleted in male BXSB.Yaa mice. We generated BXSB.Yaa and NZW mouse strains in which the β2 GPI gene had been knocked out by backcrossing the wild-type strains with C57BL/6 β2 GPI(-/-) mice for 10 generations. Sex- and age-matched mice of the various strains were housed under identical conditions and were killed at fixed time intervals. Serum and tissue specimens were collected at various time points. Lupus-associated autoantibodies, inflammatory cytokines, and the type I interferon (IFN) gene signature were measured. Flow cytometric analyses of lymphocyte populations were performed. The severity of glomerulonephritis was graded by 2 independent renal histopathologists. Male BXSB.Yaa β2 GPI(-/-) mice developed significant lymphadenopathy and splenomegaly compared with age-matched controls. Male BXSB.Yaa β2 GPI(-/-) mice also had significantly higher levels of autoantibodies, increased levels of inflammatory cytokines including tumor necrosis factor α, interleukin-6, and BAFF, and more severe glomerulonephritis. The type I IFN gene signature in male BXSB.Yaa β2 GPI(-/-) mice was significantly higher than that in control mice. Male BXSB.Yaa β2 GPI(-/-) mice also had marked dysregulation of various B cell and T cell populations in the spleens and lymph nodes and a disturbance in apoptotic cell clearance. Deletion of β2 GPI accelerates and potentiates the autoimmune phenotype in male BXSB.Yaa mice.
Heart, Lung and Circulation
PLOS ONE, 2015
Objective Angiotensinogen exists in two distinct redox forms in plasma, the oxidized sulfhydryl-b... more Objective Angiotensinogen exists in two distinct redox forms in plasma, the oxidized sulfhydryl-bridge form and the reduced, unbridged, free thiol form. The oxidized form of angiotensinogen compared to the free thiol form preferentially interacts with renin resulting in increased generation of angiotensin. The predictive potential of the ratio of free-thiol to oxidized angiotensinogen in the plasma for pre-eclampsia was first suggested by the Read group in ref 10. We propose an improved method for determining the ratio and validate the method in a larger cohort of pregnant women.
Antioxidants & redox signaling, 2015
Age-related macular degeneration (AMD) affects the region of the retina responsible for high reso... more Age-related macular degeneration (AMD) affects the region of the retina responsible for high resolution vision. It is a major cause of blindness in the ageing population. This is the first study to examine the association of redox modified, cysteine based, post-translational forms of beta 2-glycoprotein I (β2GPI) in the plasma of individuals with early and late stages of patients with AMD compared to controls. Exploration is also undertaken to assess whether the free thiol form of β2GPI versus the oxidized disulfide form have distinct functional properties in the setting of hydrogen peroxide mediated cell death of an immortalized human retinal pigment epithelium (RPE) cell line. We demonstrate β2GPI in the retina and choroid of patients with AMD. Free thiol β2GPI is shown to protect the immortalized human RPE cell line against H2O2 induced cell death, whereas the oxidized form of β2GPI and free thiol bovine serum albumin were not protective. Free thiol β2GPI levels were significantl...
Hematology, 2014
This chapter reviews several important themes pertaining to the antiphospholipid syndrome (APS), ... more This chapter reviews several important themes pertaining to the antiphospholipid syndrome (APS), including a description of the clinical features, a discussion of the main autoantigen, beta 2-glycoprotein I (β2GPI), and insights into the characteristics of the pathogenic anti-β2GPI autoantibodies. Evidence-based considerations for when to test for APS are explored, along with the clinical significance of patients testing positive on multiple APS assays, so-called triple positivity. A detailed review of recently published laboratory guidelines for the detection of lupus anticoagulant and the solid-phase anticardiolipin and anti-β2GPI ELISAs is undertaken. Finally, a brief review of nonclassification criteria laboratory assays with potential future diagnostic utility is presented.
Thrombosis Research, 2004
Beta-2 glycoprotein I (β2GPI) is the principal target of autoantibodies in the antiphospholipid s... more Beta-2 glycoprotein I (β2GPI) is the principal target of autoantibodies in the antiphospholipid syndrome (APS). It is abundant in human plasma and shares high homology between different mammalian species. Although the exact physiological function of β2GPI has not been fully elucidated, several interactions have been described with other proteins and with negatively charged surfaces, such as anionic phospholipids, dextran and heparin. β2GPI is involved in the coagulation pathway, exerting both procoagulant and anticoagulant activities. Plasma from β2GPI-deficient mice exhibits impaired thrombin generation in vitro. Recently, it has been demonstrated that β2GPI binds factor (F) XI in vitro at concentrations lower than those of the protein in human plasma, and this binding inhibits FXI activation to FXIa by thrombin and FXIIa. Proteolytic cleavage of the fifth domain of β2GPI abolishes its inhibition of FXI activation and results in reduced ability of the cleaved β2GPI to bind phospholipids. It retains its ability to bind FXI. In vivo activation of FXI by thrombin is thought to be an important mechanism by which coagulation is accelerated via components of the contact activation pathway. Thus β2GPI may attenuate the contact activation pathway by inhibiting activation of FXI by thrombin. Moreover, because β2GPI is the dominant autoantigen in patients with APS, dysregulation of this pathway by autoantibodies may be an important mechanism for thrombosis in patients with APS.
Rheumatology, 2010
ANCA antibodies were negative. Polyclonal increase in gamma globulins. A diagnosis of primary Sjö... more ANCA antibodies were negative. Polyclonal increase in gamma globulins. A diagnosis of primary Sjö gren's syndrome was made. Case 3: A 66 year old female with an established diagnosis of Sjö gren's syndrome presented with breathlessness. Hitherto her chief symptoms had been xerostomia with episodic salivary gland swelling. She was known to have positive ANA, anti-SSA, anti-SSB and cardiolipin antibodies, as well as rheumatoid factor. A salivary gland biopsy had demonstrated changes consistent with Sjö gren's syndrome. Chest CT showed a number of uniform thin-walled cysts evenly scattered throughout both lungs, with subtle subpleural interstitial changes only and no pulmonary infiltrate. Conclusions: Estimates of the frequency of lung cysts in primary Sjö gren's range from 8 to 46%. However, in most reports cysts are described in conjunction with ground glass changes and bronchiectasis; these two are generally viewed as the most typical lung changes in Sjö gren's syndrome. However, our experience suggests that cystic disease as the predominant lung finding in Sjö gren's is not uncommon. Moreover, as these cases demonstrate, the presence of cysts can assist both in making the diagnosis (case 1) and in differentiating Sjö gren's from other connective tissue diseases (case 2). Primary Sjö gren's syndrome should be considered when cystic lung disease is found.