Antiphospholipid Syndrome ( APS) Edward John Walter Bowie, MD Mayo Medical School the first to identify APS as an acquired thrombophilia Graham Robert Vivian Hughes MD FRCP Unit Rayne Institute St Thomas Hospital UK the first to identify APS as a generalized autoimmune disorder Hassouna February 2, 2010 1
1952-1982 Several investigators reported prolonged clotting times that do not correct in mixing of SLE patient plasma with normal plasma. They named the substance Circulating Anticoagulant, Acquired Inhibitor, Lupus Anticoagulant Conley CL Harman RC. A hemorrhagic disorder caused by circulating anticoagulants in patients with disseminated lupus erythymatosus. J Clin Invest 1952; 31: 621-622 Lechner K Acquired inhibitors in auto and isoimmune diseases. Hemostasis 1974; 3:65-69 Feinstein DI, Rappaport SI. Acquired inhibitors of blood coagulation In Sapet TN, Eds; Progress in Hemostasis and Thrombosis, 1rst ed. Grune and Stratton New York, NY: 1982;6:263-285. Hassouna February 2, 2010 2
1952-1963 APS is considered a hemorrhagic disease 1963 is linked to thrombosis. 1983 LA is identified 1952-1963 Circulating anticoagulants in SLE are named lupus anticoagulants ( LA) because they prolong the clotting times in phospholipid dependent assays. LA believed to cause clinical hemorrhagic disease 1963 LA are reported by Bowie et al to be associated with thrombosis in SLE patients. 1983 LA are identified by Harris et al to be antibodies that react with cardiolipin Lupus anticoagulants react with purified cardiolipin and they are identified as anticardiolipin antibodies by RIA Hassouna February 2, 2010 3
1952-1963 Lupus Anticoagulant believed to cause hemorrhagic disease. Also named circulating anticoagulant Lupus anticoagulant was applied to a clotting test that generates a prolonged clotting time in SLE patient plasma that did not correct when mixed in equal volume with pooled normal plasma. Hassouna February 2, 2010 4
In 1963, Dr Bowie reported several cases of thrombosis in SLE despite circulating anticoagulants. This was the first report of an acquired thrombophilia. Thrombophilia is an inherited or acquired clinical phenotype that manifests in selected individuals as a greater risk to develop thrombosis in response to an ENDOGENOUS stimulus than the general population Bowie EJW, Thompson JH,, Pascuzzi CA, Owen CA. Thrombosis in systemic lupus erythematosus despite circulating anticoagulants. J Lab Clin Med 1963; 62: 416-430 Hassouna February 2, 2010 5
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Gala dinner Penner Blood Coagulation Conference held in honor of Walter Bowie Hassouna February 2, 2010 7
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Lupus anticoagulant identified in 1983 by the anticardiolipin test to belong to the family of antiphospholipid antibodies Introduction of the anticardiolipin test identified the lupus anticoagulant as auto-antibodies directed at cardiolipin, a phospholipid in inner mitochondrial membranes Harris EN, Gharavi AE, Boey ML. Anticardiolipin antibodies: detection by radioimmunoassay and association with thrombosis in systemic lupus erythematosus. Lancet 1983; 2: 1211-1214 Hassouna February 2, 2010 9
Two mechanisms are identified in the induction of autoimmune Antiphospholipid antibodies (a PL) Apoptotic phospholipid protein complexes generate antibodies a PL From experiments in mice, a PL are produced by binding of beta2- glycoprotein 1 to phospholipid viral or bacterial proteins by molecular mimicry Hassouna February 2, 2010 10
Cardiolipin is a phospholipid on the inner membrane of mitochondria first identified in bovine heart. Anticardiolipin antibodies ( lupus anticoagulant) represent an autoimmune process Hassouna February 2, 2010 11
Autoimmune a PL are generated by apoptotic phospholipid protein complexes in mitochondria and other cellular components Increased apoptosis as observed in blood of SLE patients, followed by enhanced phosphatidyl serine exposure provides molecular signal to macrophages and other antigen presenting cells leading to a PL Hassouna February 2, 2010 12
Antiphospholipid antibodies are a heterogeneous group with a variety of target antigens. The most significant target antigen is the B2-glycoprotein 1 In 1990 Monica Galli and her group in Bergamo, Italy reported that the true antigenic targets of antiphospholipid antibodies are not the phospholipids but plasma proteins bound to an anionic surface. Galli M,Comfurius P, Massen C et al. Anticardiolipin antibodies (ACA) directed not to cardiolipin but to a plasma protein co-factor. Lancet 1990;334: 1544-1547 Hassouna February 2, 2010 13
Reproduced with permission Chethan Puttarajappa, MD review article submitted in fulfillment for the thrombosis rotation requirement beta-2-glycoprotein 1 is the most common and best-characterized antigenic target of auto-immune antiphospholipid antibodies. Beta-2 glycoprotein 1, also known as apolipoprotein H is an anticoagulant plasma protein belonging to the complement control protein family, and it is present in plasma at a concentration of approximately 150-300 micrograms per milliliter. Beta-2 glycoprotein 1 anticoagulant action is by interaction with anionic phospholipids via a lysine rich region in the extra 20 amino acid C-terminal loop of the fifth domain that prevents thrombin amplification by the prothrombinase activity and prevents ADP induced platelet aggregation Hassouna February 2, 2010 14
. Domain specificity of anti-β 2 -GPI antibodies as suggested by different research groups. Schematic picture of β 2 -GPI with the five domains (A) and crystal structure of β 2 -GPI (B) [18]. Hassouna February 2, 2010 15
Induction of experimental a PL in naive mice: β2gpi epitope mimicry with bacterial particles. Hassouna February 2, 2010 16
Molecular mimicry between β2gpi and common bacteria/viruses. The sequence similarity of these proteins to the domain 5 phospholipid binding region of beta2-glycoprotien 1 breaks the tolerance to self beta2-glycoprotein 1 and induces antibodies against t he beta2-glycoprotein 1 lysine rich phospholipid binding region CLOSE Hassouna February 2, 2010 17
Interaction of β 2 -GPI with ApoER2 receptor on platelets. After dimerization by anti-β 2 -GPI autoantibodies subsequently, β 2 -GPI can bind to anionic phospholipids on the membrane of the platelet. β 2 -GPI binds to the ApoER2 receptor. This reaction results in the release of thromboxane A2. Hassouna February 2, 2010 18
In 1984, a group of rheumatologists led by Graham Hughes found that in their sizeable collection of SLE patients the Lupus anticoagulant occurred with some frequency and was associated with thrombosis and thrombocytopenia and this raised the possibility that patients with the lupus anticoagulant and anti-cardiolipin antibodies might be a part of a larger body of patients with systemic auto-immune diseases Hassouna February 2, 2010 19
Patients with LA are part of a larger body of patients with systemic autoimmune diseases conditions caused by the breakdown of immune tolerance and resultant immune responses to self-antigens. Auto-reactive CD4+ and CD8+ T cells t induce tissue damage in patients with various autoimmune diseases, including immune thrombocytopenic purpura, antiphospholipid syndrome, and myasthenia gravis. Hassouna February 2, 2010 20
who symptoms conferences membership newswe are what diagnosis publications fundraising events we do treatment patient shop research FAQs research activities publicity prognosis Hassouna February 2, 2010 21
Catastrophic APS Asherson Syndrome Lupus anticoagulant discriminates from DIC and TTP There is a small group of APS patients who present with occlusive events at multiple sites over a short period of time resulting in multi organ failure. The majority of catastrophic episodes are preceded by a precipitating events mainly infections Less than 1% of APS patients Hassouna February 2, 2010 22
Antiphospholipid Syndrome has 3 components: Lupus anticoagulant is a term applied to a prolonged clotting time in a phospholipid dependent clotting test Antiphospholipid antibodies is a general term applied to antibodies generated by an autoimmune or an infectious process An acquired thrombophilia ( arterial and venous thrombosis, recurrent pregnancy loss, thrombocytopenia) caused by autoimmune or infectious processes that generate antibodies harmful to endothelium and platelets. Hassouna February 2, 2010 23
Antiphospholipid Syndrome Clinical Phenotype Arterial and venous Thrombosis Obstetric complications Recurrent miscarriages Pre-eclampsia Intrauterine growth retardation Thrombocytopenia Hassouna February 2, 2010 24
Significance of the Lupus anticoagulant in the diagnosis of APS Hassouna February 2, 2010 25
Lupus Anticoagulant Lupus anticoagulant is a term applied to a clotting test that generates a prolonged clotting time in the patient s plasma that does not correct when mixed in equal volume with pooled normal plasma. Hassouna February 2, 2010 26
Lupus anticoagulants are stronger risk factors for thrombosis than anticardiolipin antibodies in the APS syndrome: a systemic review of the literature. Monica Galli, David Luciani, et al Blood 2003;101: 1827-1832 Hassouna February 2, 2010 27
Litterature search stategy on the association between a PL and thrombosis. Study desigh chort prospective, cross sectional, case control, ambispective, retrospective. Galli, M. et al. Blood 2003;101:1827-1832 Copyright 2003 American Society of Hematology. Copyright restrictions may apply. Hassouna February 2, 2010 28
Studies on lupus anticoagulants and anticardiolipin antibodies Figure 2 All studies reported a significant 95% CI between lupus anticoagulants and, and thrombosis and the odds ratio ranged from 5-71 to 9.4 Hassouna February 2, 2010 29
Figure 3. Galli, M. et al. Blood 2003;101:1827-1832 Copyright 2003 American Society of Hematology. Copyright restrictions may apply. Hassouna February 2, 2010 30
Figure 6. Galli, M. et al. Blood 2003;101:1827-1832 Copyright 2003 American Society of Hematology. Copyright restrictions may apply. Hassouna February 2, 2010 31
Table 1.. Strength of the association between lupus anticoagulants, anticardiolipin antibodies, and thrombosis Type of thrombosis Lupus anticoagulan ts * Odds ratio range Anticardioli pin antibodies * Odds ratio range Arterial 2/2 8.65-10.84 13/19 NS-18 Venous 5/5 4.09-16.2 2/12 NS-2.51 Any 2/2 5.71-7.3 1/2 NS-3.66 Hassouna February 2, 2010 32
Clinical Utility of Laboratory tests used to identify APS antibodies and to diagnose the APS Galli M Semin Thromb Hemost 2008; 34: 329-334 Lupus Anticoagulant is essentially a measure of the functional activity of subgroups of a PL directed against beta2-glycoproein 1 Hassouna February 2, 2010 33
Fig. 1. Testing algorithm for clinical features suggesting antiphospholipid syndrome (APS). Reprinted from J Autoimmunity 2000; 15(2): 81 85. Used with permission. β 2 GPI: β 2 glycorpotein I, ELISA: enzyme-linked immunosorbent assay. Hassouna February 2, 2010 34
CLOSE Hassouna February 2, 2010 35
Special Coagulation Laboratory Recipe for APS diagnosis APTT clotting times must be prolonged at least one and half times control plasma clotting times APTT prolonged clotting times does not correct in mixing patient plasma with pooled normal plasma ELISA identifies beta2-glycoprotein 1 antibodies. Testing is repeated when necessary. APS induced by viral or bacterial proteins disappears after infection is cured Hassouna February 2, 2010 36
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Question 1 A 57 years old female with lupus erythematosus presents with a deep venous obstruction of the left calf confirmed by Doppler ultrasound. Which of the following indicates a result positive for the APS. 1) Prothrombin time ( PT) 11.4 sec. Activated Partial Thromboplastin time ( APTT) 26.4 sec within normal range. Positive anticardiolipin antibodies. 2) PT 21 sec markedly prolonged. APTT 26.4 sec within normal range. Thrombin clotting time prolonged 16 sec (Control 8.2 sec). Thrombin clotted Fibrinogen 0.5 gram per liter (normal range 2-4 gram per liter). Immunoreactive fibrinogen 3 gram per Liter.( normal range 2-4 gram per liter) 3)PT 12.5 sec ( within normal range) APTT 48 sec ( prolonged) APTT does not correct in mixing studies. Negative anti-cardiolipin, anti-phospholipid, and beta-2- glycoprotein-1 antibodies. 4) PT 12.5 sec ( within normal range) APTT 48 sec ( prolonged) APTT does not correct in mixing studies. Positive anti-beta-2-glycoprotein-1 antibodies. Hassouna February 2, 2010 39
Question 2 A 57 years old female with lupus erythematosus and a deep venous obstruction of the left calf confirmed by Doppler ultrasound, she tested positive for the antiphospholipid syndrome and was managed by conventional anticoagulation. After 6 months, results of a repeat Doppler ultrasound indicate complete resolution of the venous obstruction. One of the following is the correct choice for long term management: 1) Test for inherited thrombophilia to determine if patient remains on lifelong oral anticoagulation. 2) Antiphospholipid syndrome is an inherited thrombophilia requiring life long oral anticoagulation 3) Lifelong anticoagulation is indicated because thrombosis risk is extremely high (DVT, age, 4) antiphospholipid syndrome, lupus erythymatosus) 5) Complete resolution of venous obstruction indicates adequate hemostasis. Stop oral anticoagulation. Hassouna February 2, 2010 40
Question 3 Chose the correct causative mechanism for arterial and venous thrombosis and repeated fetal loss in the antiphospholipid syndrome 1)Activation of clotting factor XI by antiphospholipid antibodies 2) The lupus anticoagulant damages the venous and arterial endothelium by complement activation 3) anti-beta 2 glycoprotein 1 antibodies bind antithrombin and markedly decrease natural anticoagulant plasma levels 4) Autoimmune antiphospholipid antibodies act by either one or by all the following mechanisms a) activation of complement, b) induction of tissue factor expression and cell adhesion receptors on endothelial cells c) promoting platelet aggregation, Hassouna February 2, 2010 41