Antiphospholipid syndrome was described in full in the 1980s, aftervarious previous reports of specificantibodies in people with systemic lupus "Hughes”erythematosus and thrombosis.The syndrome is sometimes referred to as "Hughes syndrome",after the rheumatologist Dr. Graham R.V. Hughes who workedat the Louise Coote Lupus Unit at St Thomas Hospital in Londonand played a central role in the description of the condition.
• In young,app healthy people---for LA, antiCL is 1-5%• Prevalence ↑ with age ,in elderly with chronic disease.• Mean age of onset-31 yrs,Low age 8 months• Risk of thrombosis is 0.5-30%• Women :men is 5:1• Females---arthritis,livedo,migraine• Males—MI,epilepsy,lower extremity arterial thrombosis• More common in african americans.• Without rheumatic disease at younger age and with rh –older• Apl ab—30-40% in SLE---10% have APLS• Idiopathically—ACL-24%,LA-4%
Antiphospholipid syndrome or antiphospholipid antibodysyndrome (APS or APLS or), often also Hughes syndrome,is an autoimmune, hypercoagulable state caused by antibodiesagainst cell-membrane phospholipids that provokes blood clots(thrombosis) in both arteries and veins as well aspregnancy-related complications such asmiscarriage, stillbirth, preterm delivery, or severe preeclampsia.The syndrome occurs due to the autoimmune production ofantibodies against phospholipid (aPL), a cell membrane substancIn particular, the disease is characterised by antibodies againstcardiolipin (anti-cardiolipin antibodies) and β2 glycoprotein I.
Risk factors for developing antiphospholipid syndrome include:•Primary APS genetic marker HLA-DR7•Secondary APS SLE or other autoimmune disorders Genetic markers: HLA-B8, HLA-DR2, HLA-DR3 Race: Blacks, Hispanics, Asians, and Native Americans
Disruption of vascular endothelial lining allows exposure of blood to subendothelial connective tissue:Primary hemostasis (seconds)- Platelet plug formation at site of injury- Stops bleeding from capillaries, small arterioles and venulesSecondary hemostasis (minutes)- Fibrin formation by reactions of the plasma coagulation system
Defects in primary hemostasis• ThrombocytopeniaDefects in secondary hemostasis• Clotting factor deficiencies• Prethrombotic (hypercoagulable) states
• Anti-thrombin deficiency• Deficiencies of protein C and S• Resistance to activated protein C•( factor V Leiden mutation)• Prothombin gene mutation Conditions associated with a hypercoagulable state:• ( G20210A) - pregnancy and postpartum - major surgeryHomocystinemia - obesity and immobility - malignancy - congestive heart failure - nephrotic syndrome Estrogen treatment Antiphospholipid syndrome
Antiphospholipid syndrome is an autoimmune disease, in which"antiphospholipid antibodies" :1.anticardiolipin antibodies (ACA)2. lupus anticoagulant(LA)react against proteins that bind to anionic phospholipids onplasma membranes.ACA– are directed against cardiolipinThey may be b2 gp1 dependent or independent(Independent—syphilis)
• B2 gp1-----apolipoprotein H• Bind with cardiolipin ab - thrombosis• 2GPI a plasma protein with affinity for negatively charged phospholipids• anti- 2GPI: are probably the major cause of APS• Anticardiolipn abs recognize in most assays: 2 GPI• Lupus Anticoagulant activity is caused by autoantibodies to: - 2 GPI - prothrombin
Anionic phospholipidsThe exact cause is not known, butactivation of the system of coagulation isevident.
• Homeostatic regulation of blood coagulation is altered.• 1.defect in cellular apoptosis- exposure of membrane phospholipids to the binding of various plasma proteins---b2gp1---complex—epitope---target for autoantibodies.• 2.oxidized b2GP1---activates dendritic cells –autoantibodies are produced.• 3.production of antibodies against prothrombin, proteinC, S annexins.• 4.activation of platelets to enhance endothelial adherence.• 5.activation of vascular endothelium—platelet and monocyte binding.• 6.ab against oxidized LDL — atherosclerosis.
• Complement activation has been increasingly recognised as a possible significant role in the pathogenesis of APS. Blood. Jan 15 2007;109(2):422-30. Nat Med. Nov 2004;10(11):1222-6.The family of APL ab are heterogenous and the targets vary.APS can be caused by –LA,ACA,B2GP1 or other antibodies.There are distinct clinical ,laboratory and biochemical differences between the disorders mediated by the different antibodies.ACL---risk of stroke—arterial thrombosisLA-venousTNF alpha –pregnancy loss
Clinically important antiphospholipid antibodies (those thatarise as a result of the autoimmune process) are associatedwith thrombosis and vascular disease.The syndrome can be divided into primary (no underlyingdisease state) and secondary (in association with an underlyingdisease state) forms.Anti-ApoH and a subset of anti-cardiolipin antibodies bind to ApoH,which in turn inhibits Protein C, a glycoprotein with regulatoryfunction upon the common pathway of coagulation (by degradatingactivated factor V).
LAC antibodies bind to prothrombin , thus increasing its cleavage tothrombin, its active form .In APS there are also antibodies binding to: Protein S, which isa co-factor of protein C.Thus, anti-protein S antibodies decrease protein C efficiency;Annexin A5, which forms a shield around negatively-chargedphospholipid molecules, thus reducing their availability forcoagulation.Thus, anti-annexin A5 antibodies increase phospholipid-dependent coagulation steps.
The Lupus anticoagulant antibodies are those that show theclosest association with thrombosis, those that targetβ2glycoprotein 1 have a greater association with thrombosisthan those that target prothrombin.Anticardiolipin antibodies areassociated with thrombosisat moderate to high titres(>40 GPLU or MPLU).Patients with both Lupus anticoagulant antibodies andmoderate/high titre anticardiolipin antibodies show a greater riskof thrombosis than with one alone .
APL antibodies and NF- B• Intracellular events in EC induced by aPL antibodies: – aPL induce activation of NF- B and correlates with EC activation in vitro and in vivo and with thrombosis in vivo. • Espinola RG et al: J Thromb Haemost, 2003; 1: 843-848. • Dunoyer-Geindre S. et al. Thromb Haemost. 2002; 88: 851-857. • Bohgaki M, et al. Int Immunol. 2004; 16: 1632-1641.
is characterized by:• Arterial or Venous Thrombosis• Thrombocytopenia• Recurrent Fetal Loss• Serum Anti-phospholipid antibodies (aPL)
1. Primary antiphospholipid syndromeAPS occurs in the absence of any other related disease.2. Secondary antiphospholipid syndromeAPS occuring in the context of other autoimmunediseases, such as systemic lupus erythematosus (SLE).3. Catastrophic antiphospholipid syndromeIn rare cases, APS leads to rapid organ failure due togeneralised thrombosis; this is termed (CAPS) and isassociated with a high risk of death.
• Venous thromboembolism: Arterial Occlusion:Deep Vein Thrombosis Stroke and TIAs are the most common Pulmonary Embolism
• Pregnancy morbidityRecurrent fetal loss• In women with recurrent miscarriage due to APS fetal loss rate: as high as 90%• antiphospholipid abs are associated with: - placental insufficiency - early preeclamapsia - IUGR- intrauterine growth restriction
Sydney revsion of Sapporo criteria 2006aPL associated manifestations (individual diagnosis)• Thrombocytopenia (occurs in up to 50%)• Cardiac valve disease• Livedo reticularis• Nephropathy ( late manifestation) Livedo reticularis with necrotic finger tips in Antiphospholipid syndrome
not included in criteria• Transverse myelitis• Migraine• Chorea• Leg ulcers• UBOs (white matter lesions) on brain MRI
• Infection: - Syphilis, TB, Q-fever, Spotted Fever, Klebsiella, HCV, Leprosy,HIV. - The abs are usually transient, not 2 GPI dependent• Malignancy: Lymphoma, paraproteinemia• Drug induced: phenothiazines, procainamide, quinidine, phenytoin, hydralazine
Common auto immune diseases ass with APL ab are• 1.SLE-25-50%• 2.sjogren‘s –42%• 3.RA-33%• 4.AITP-30%• 5.AIHA-unknown• 6.MCD-22%• 7.behcet-20%
• Spontaneous venous thromboembolism• Recurrent VT, even in presence of other risk factors• Stroke or peripheral arterial occlusive event at < 50 yrs• In all SLE patients• In women with > 3 consecutive pregnancy losses loss of morphologically normal fetus at II-III trimester early severe preeclampsia low prevalence in general obstetric severe placental insufficiency population (< 2% ): screening not warranted
• APA---IgG,IgA,IgM• SEVERAL antibodies are recognised• Recently—antibodies against annexin V,protein C• IgM acl---HEMOLYTIC ANEMIA.• IgG ACL –thrombosis• False positive test result for syphilis• ACL—membrane phospholipids• LA-plasma coagulation molecules• Elongates APTT,Kaolin clotting time,dilute russells viper venom time.
• Advantages – Overwhelming majority of APS patients are anti cardiolipin positive – Test can be performed reproducibly. – Clinicians and laboratories generally familiar with units of measurement.• Disadvantages – Relatively nonspecific (particularly low positive, IgM positive). – Intra-laboratory and Inter-laboratory variability. – Problems with false positive results: aCL positive in a wide variety of infectious diseases and in non-APS related autoimmune diseases.
Solid phase assays usually anti-Cardiolipin abs
Predictive value of IgG aCL for thrombosis in patients with SLE• IgG aCL levels below 21.4 = probability of thrombosis 0.07• IgG aCL levels >21.4 and < 65.0 GPL = probability of thrombosis 0.20• IgG aCL levels >65.1 GPL units = probability of thrombosis 0.75
• Perform coagulation screen to detect prolongation in phospholipid dependent coagulation assay (usually use: APTT)• If APTT is prolonged: Mix with normal plasma - If due to factor deficiency: corrected - If due to inhibitor (antibody) not corrected• Confirm inhibitor is phospholipid dependent : corrected by mixing with platelets or phospholipids• Perform second test: KCT or DRVVT
No LAC shows 100% specificity and sensitivity because aPLs are• APTT: heterogeneous. - variability in reagents result in More than 1 test system is needed inconsistent sensitivity. - acute phase reaction and pregnancy may shorten APTT and mask a weak LAC A normal APTT does not exclude LAC• KCT- Kaolin clotting time more sensitive to presence of anti-II• DRVVT- Dilute Russell‘s viper venom time more sensitive to presence of 2 GPI• TTI - Tissue thromboplastin inhibition test
Principle• Based on observation that antiphospholipid antibodies cross- react with negatively charged phospholipids but syphilis and other infectious diseases sera largely limited to cardiolipin binding (no cross-reactivity)• Construction of a kit with negatively charged phospholipids might eliminate non-specific binding.• Antigen composed of mixture of phospholipids instead of cardiolipin• Sensitivity of APS (greater than 90%)• More specific than anticardiolipin test and at least as specific (or more) compared to anti-ß2GPI• Incorporation of an in-house positive control• Can be utilized for first line testing, and certainly important in confirmation of APS
Patient Laboratory DataPT 20.6 sec aPTT 100.3 secTCT 8.8 sec DRVVT „No clot‟Factor „Inhibitory‟ Factor IX <1.6%VIIIFactor XI <1.6% Bethesda 2.8 U titerPlatelets 120,000/ Factor X 68% l
Additional Laboratory DataFactor V (aPTT) “Inhibitory”Factor V (PT) 115%Factor II 38%Fibrinogen 795.6 mg/dlD-dimer >4.37 mcg FEU/mlRepeat DRVVT (ratio) 3.23DRVVT Confirm (ratio) 2.17
Alternative strategies to identify a lupus anticoagulant• Platelet neutralization procedure (PNP; uses platelet membranes).• Hexagonal phase phospholipid assay (StaClot LA; uses PE in a hexagonal phase conformation).• Textarin/Ecarin clot time.• Factor V analysis by PT and aPTT-based assays.
What if LA,ACL are negative• If patient experiencing thrombosis or recurrent miscarriages• Order• Antibodies to b2 gp1• Ab to phosphatidyl serine,ethonalamine,glycerol,inositol• Annexin V• Phosphatidyl choline.
Imaging studies• For confirmation• USG• COLOR DOPPLER• CT SCAN• MRI• 2D ECHO• Histology----• non inflammatory bland thrombosis with no signs of perivascular inflammation or leukocytoclastic vasculitis.
• Lupus anticoagulant detected and confirmed.• Multiple factor deficiencies in aPTT pathway reflect high-titer lupus anticoagulant.• Prolonged PT reflects mild factor II deficiency and lupus anticoagulant effect.• Elevated D-dimer reflects recent thrombosis.• Elevated inhibitor titer due to lupus anticoagulant.
DIFFERENTIAL DIAGNOSIS• Think of any other thrombophilic states before making a diagnosis of APLS.• Malignancy• OCP• Homocysteinemia• Antithrombin 111 def• Protein C,S def• Factor V leiden mutation
Incidental finding of antiphospholipid antibodies• Anti-thrombotic therapy not usually indicated• Low threshold for thromboprophylaxis at times of high risk• Some suggest low dose Aspirin prophylaxis• Reduce other risk factors for thrombosis
INR• The ISI—1.0-2.0• INR—5 high chance of bleeding• 0.5--- clot formation• Normal range is 0.9-1.3• Warfarin ---2.0-3.0• Prosthetic valves—3.0-4.0
Prophylactic therapy• Eliminate other risk factors, such as oral contraceptives,smoking, hypertension, or hyperlipidemia.• Low-dose aspirin is used widely in this setting; however, theeffectiveness of low-dose aspirin as primary prevention forAPS remains unproven.• Clopidogrel has anecdotally been reported to be helpful inpersons with APS and may be useful in patients allergic toaspirin.• In patients with SLE, consider hydroxychloroquine, whichmay have intrinsic antithrombotic properties.•Consider the use of statins, especially in patients withhyperlipidemia.
Thrombosis• Perform full anticoagulation with intravenous or subcutaneousheparin followed by warfarin therapy.• Based on the most recent evidence, a reasonable target for theinternational normalized ratio (INR) is 2.0-3.0 for venous thrombosisand 3.0 for arterial thrombosis.• Patients with recurrent thrombotic events, while well maintainedon the above regimens, may require an INR of 3.0-4.0.• For severe or refractory cases, a combination of warfarin andaspirin may be used.•Treatment for significant thrombotic events in patients with APS isgenerally lifelong.
Management of aPL positive patients with adverse pregnancy history• Poor obstetric history - the most important predictor• The risk of fetal loss is related to aCL ab titer• Presence of aPL are a marker for a high risk pregnancy• Once APS is diagnosed, serial aPL testing is not useful
Current RecommendationsPregnancy Fetal protection• Asymptomatic aPL no treatment• Single loss <10wks no treatment• Recurrent loss* <10wks prophylactic heparin +ASA up to 6-12 wks postpartum, ASA after(?)• Recurrent loss < 10 wks therapeutic heparin + ASA, + thrombosis warfarin postpartum• Prior thrombosis therapeutic heparin + ASA warfarin postpartum * Late fetal loss IUGR severe pre- eclampsia
Other therapies for aPL associated pregnancy loss• Corticosteroids : - associated with significant maternal and fetal morbidity - ineffective• Immunosuppression: azathioprine, plasmapheresis: numbers treated too small for conclusion• IVIG: may be salvage therapy in women who fail on Heparin + Aspirin
Fetal Monitoring• US monitoring of fetal growth and amniotic fluid every 4 weeks• US monitoring of uteroplacental blood flow: uterine artery waveforms assessed at 20-24 wks• If early diastolic notch seen: do 2 weekly growth scans due to high risk of IUGR
FOLLOW UP• Frequent check ups• Adequate patient education• Avoidance of smoking• Strict control with anticoagulants.• In case of bleeding –hospital.• Normal healthy life
PrognosisWith appropriate medication and lifestyle modifications, mostindividuals with primary antiphospholipid syndrome (APS) leadnormal healthy lives. However, subsets of patients continue to have thrombotic eventsdespite aggressive therapies. In these patients and in patients withCAPS, the disease course can be devastating, often leading tosignificant morbidity or early death.A retrospective study suggested that hypertension or medium-to-hightiters of IgG anticardiolipin antibody are risk factors for a firstthrombotic event in asymptomatic patients with antiphospholipid(aPL) antibodies. Primary prophylaxis against thrombosis appearsto offer significant protection in such cases.
Patients with secondary APS carry a prognosis similar tothat of patients with primary APS; in the former, however,morbidity and mortality may also be influenced by thesepatients underlying autoimmune or rheumatic condition. Inpatients with SLE and APS, aPL antibodies have beenassociated with neuropsychiatric disease and have beenrecognized as a major predictor of irreversible organdamage.Women with aPL antibodies who experience recurrentmiscarriages may have favorable prognoses in subsequentpregnancies if treated with aspirin and heparin.
Future Directions• Can we predict which patients with antiphospholipid antibodies will develop thromboembolic complications?• Is there an inherited predisposition to developing antiphospholipid antibody syndrome?
Genomic strategy• Whole blood RNA prepared using PAXgene system from patients with APS and selected control populations.• RNA extracted and validated.• Oligonucleotide arrays printed at the Duke Microarray Facility, using the Operon Human Genome Oligo Set Version 3.0 (Operon, Huntsville, AL). -- Potti, et al., Blood, 2006; 107: In press.
Discovery ModePreliminary data with patients and ‗controls‘Controls with VTE APS aPLA Normal Up regulated Down regulated -- Potti, et al., Blood, 2006; 107: 1391.
Family history Mother developed arterial thrombosis and thrombocytopenia prior to her death. Asymptomatic daughter tests positive for a lupus anticoagulant.
Familial Antiphospholipid Syndrome• Family members of patients with APS have an increased incidence of autoimmune disorders.• ―Genetics of APS‖ is a clinical trial being developed by the Rare Thrombotic Diseases Clinical Research Consortium.