Coag cascade for fellows

1. Coagulation SystemCoagulation System
Gerald A. Soff M.D.Gerald A. Soff M.D.
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2. Coagulation CascadeCoagulation Cascade
Choose one or more of the following;Choose one or more of the following;
1. If I could memorize all of “CDs”, why can’t I1. If I could memorize all of “CDs”, why can’t I
remember the blasted coagulation cascade?remember the blasted coagulation cascade?
2. O.K., so I figured out Factors I, II, V, VII,2. O.K., so I figured out Factors I, II, V, VII,
VIII, IX, X, XI, and XII. So where the hell isVIII, IX, X, XI, and XII. So where the hell is
factor III, IV, and VI?factor III, IV, and VI?
3. And why do they use Roman Numerals? I3. And why do they use Roman Numerals? I
cancan’t read my damned notes!’t read my damned notes!
4. Who cares about this stuff anyway, I4. Who cares about this stuff anyway, I’m going’m going
into oncology!into oncology!
2

3. HemostasisHemostasis
Hemostasis;Hemostasis; “The processes of keeping the blood“The processes of keeping the blood
liquid in the vasculature”liquid in the vasculature”
– Prevention of hemorrhage following vascular injury.Prevention of hemorrhage following vascular injury.
– Prevention of excessive clotting (thrombosis) in the vasculature.Prevention of excessive clotting (thrombosis) in the vasculature.
Primary Hemostasis;Primary Hemostasis;
– Vascular forces (vasoconstriction) and platelet plugVascular forces (vasoconstriction) and platelet plug
Secondary Hemostasis;Secondary Hemostasis;
– The coagulation factorsThe coagulation factors
Physiologic Anticoagulation processesPhysiologic Anticoagulation processes
– Neutralize activated factors where vessels are intact.Neutralize activated factors where vessels are intact.
– FibrinolysisFibrinolysis
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4. A Series Of Perspectives On TheA Series Of Perspectives On The
Coagulation System/CascadeCoagulation System/Cascade
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5. Original Publication Of Coagulation Cascade:Original Publication Of Coagulation Cascade:
Davie, E. W., and Ratnoff, O. D. (1964) Waterfall sequence for intrinsicDavie, E. W., and Ratnoff, O. D. (1964) Waterfall sequence for intrinsic
blood clotting.blood clotting. Science 145, 1310–1312Science 145, 1310–1312
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6. emedicine.medscape.comemedicine.medscape.com 6

7. Conceptual Model of HemostasisConceptual Model of Hemostasis
From Sidney Harris.
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8. XIII
Cross-Linked
Fibrin Clot
XII, PK, HMWK
XI
IX, VIII
Intrinsic
Pathway
Tissue Factor
VII
Extrinsic Pathway
X, V
II
Fibrinogen (I) Fibrin Monomer
Common Pathway
Intrinsic
Pathway
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9. 9

10. Tissue Factor;Tissue Factor;
Initiation of Coagulation CascadeInitiation of Coagulation Cascade
Primary process,Primary process, in vivoin vivo, is the extrinsic pathway., is the extrinsic pathway.
Tissue factor can be expressed by monocytes,Tissue factor can be expressed by monocytes,
fibroblasts, smooth muscle, endothelial cells.fibroblasts, smooth muscle, endothelial cells.
Tissue Factor is released in the vessel wall,Tissue Factor is released in the vessel wall,
following exposure to endotoxin, inflammation,following exposure to endotoxin, inflammation,
injury.injury.
Tissue Factor binds/activates Factor VIITissue Factor binds/activates Factor VII
TF:VIIa complex binds and activates FactorTF:VIIa complex binds and activates Factor
IX to IXa (and to a minor degree X to Xa).IX to IXa (and to a minor degree X to Xa).
10

11. Tissue Factor (TF) Expression In TheTissue Factor (TF) Expression In The
Vessel Wall.Vessel Wall.
Mackman N, The Role of Tissue Factor and Factor VIIa in Hemostasis.Mackman N, The Role of Tissue Factor and Factor VIIa in Hemostasis.
Anesth Analg 2009;108:1447–52.Anesth Analg 2009;108:1447–52.
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12. Coagulation Factors; EnzymesCoagulation Factors; Enzymes
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Serine ProteasesSerine Proteases

13. Serine ProteaseSerine Protease
•Serine, Aspartic acid, Histidine aminoSerine, Aspartic acid, Histidine amino
acids in catalytic domain.acids in catalytic domain. 13

14. Coagulation CascadeCoagulation Cascade
General FeaturesGeneral Features
Clotting factors (Factor II, VII, etc.) are zymogensClotting factors (Factor II, VII, etc.) are zymogens
(or proenzymes), which are activated to an active(or proenzymes), which are activated to an active
enzyme by limited proteolysis.enzyme by limited proteolysis.
– The enzymes in the coagulation system are serineThe enzymes in the coagulation system are serine
proteinases. (Serine, Aspartic acid, Histidine amino acidsproteinases. (Serine, Aspartic acid, Histidine amino acids
in catalytic domain)in catalytic domain)
Cofactors of CascadeCofactors of Cascade
– Tissue Factor, Factors V and VIIITissue Factor, Factors V and VIII
– Large molecules that assemble enzyme:substrate complex,Large molecules that assemble enzyme:substrate complex,
anchoring to lipid surface.anchoring to lipid surface.
The classic understanding is aThe classic understanding is a “cascade”, i.e.“cascade”, i.e.
waterfallwaterfall..
– One activated molecule activates multiple at subsequentOne activated molecule activates multiple at subsequent
stages.stages.
– The product of one step is an enzyme for the next step.The product of one step is an enzyme for the next step. 14

15. Coagulation System Is Best Understood AsCoagulation System Is Best Understood As
Series of Membrane-Bound Complexes:Series of Membrane-Bound Complexes:
Enzyme/Cofactor/SubstrateEnzyme/Cofactor/Substrate
(Modified from Furie B, Furie BC: The molecular basis of blood coagulation.(Modified from Furie B, Furie BC: The molecular basis of blood coagulation.
Cell 53:505, 1988.)Cell 53:505, 1988.) in Hoffmanin Hoffman’s Hematology Text.’s Hematology Text. 15

16. Membrane-Bound TF InitiatesMembrane-Bound TF Initiates
Coagulation CascadeCoagulation Cascade
Enzyme: VII
Cofactor: TF
Substrate: Factor IX, Factor X
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17. Procoagulant Enzyme ComplexesProcoagulant Enzyme Complexes
Complex 1 (Tissue Factor Complex)Complex 1 (Tissue Factor Complex)
– Tissue Factor, VIIa, IX and XTissue Factor, VIIa, IX and X
Complex 2 (Tenase Complex)Complex 2 (Tenase Complex)
– VIIIa, IXa, and XVIIIa, IXa, and X
Complex 3 (Prothrombinase Complex)Complex 3 (Prothrombinase Complex)
– Va, Xa, and ProthrombinVa, Xa, and Prothrombin (II)(II)
All complexes on a negatively charged phospholipid (usuallyAll complexes on a negatively charged phospholipid (usually
platelet) membrane.platelet) membrane.
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18. Procoagulant Enzyme ComplexesProcoagulant Enzyme Complexes
Enzyme Cofactor Substrate Product
TF:VII VII/VIIa Tissue Factor IX, X IXa, Xa
Tenase complex IXa VIIIa X Xa
Prothrombinase
complex
Xa Va II
(Prothrombin)
IIa
(Thrombin)
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19. 19

20. 20
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how.com/wp-
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21. Contact System:Contact System:
Initiation of Intrinsic PathwayInitiation of Intrinsic Pathway
Factor XIIFactor XII
PrekallikreinPrekallikrein
High Molecular WeightHigh Molecular Weight
KininogenKininogen
Minimal contribution to clotting, although it can activateMinimal contribution to clotting, although it can activate
Factor XI.Factor XI.
Possible role in blood pressure regulation, fibrinolysis, andPossible role in blood pressure regulation, fibrinolysis, and
inflammation.inflammation. 21

22. XIII
Cross-Linked
Fibrin Clot
XII, PK, HMWK
XI
IX, VIII
Intrinsic
Pathway
Tissue Factor
VII
Extrinsic Pathway
V, X
II
Fibrinogen (I) Fibrin Monomer
Common Pathway
22

23. So You Think You Understand TheSo You Think You Understand The
Coagulation System?Coagulation System?
Why don’t deficiencies ofWhy don’t deficiencies of “Contact“Contact
Factors” result in bleeding?Factors” result in bleeding?
Why do different deficiencies ofWhy do different deficiencies of
“Intrinsic Pathway” factors lead to“Intrinsic Pathway” factors lead to
markedly different severity ofmarkedly different severity of
bleeding, (or no bleeding)?bleeding, (or no bleeding)?
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24. XIII
Cross-Linked
Fibrin Clot
XII, PK, HMWK
XI
IX, VIII
Intrinsic
Pathway
V, X
II
Fibrinogen (I) Fibrin Monomer
Hemophilia A, B:
Severe Bleeding
Factor XI Deficiency:
Mild to no bleeding
No bleeding
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25. Tissue Factor:VIIa “Crosses” ArmsTissue Factor:VIIa “Crosses” Arms
Of The Coagulation Cascade ToOf The Coagulation Cascade To
Activate Factor IXActivate Factor IX
Complex of TF;VIIa can activate Factor X, butComplex of TF;VIIa can activate Factor X, but
primary procoagulant effect is via activation ofprimary procoagulant effect is via activation of
factor IX to IXa.factor IX to IXa.
Tissue FactorVIITF:VIIa
X Xa
IX
IXa TFPIX
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26. Complex of TF;VIIa can activate Factor X, butComplex of TF;VIIa can activate Factor X, but
primary procoagulant effect is via activation ofprimary procoagulant effect is via activation of
factor IX to IXa.factor IX to IXa. 26

27. Thrombin Feedback;Thrombin Feedback;
Activation of Factors V, VIII, XI, XIIIActivation of Factors V, VIII, XI, XIII
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28. Role of Factor XIRole of Factor XI
Factor XI is component of a positive feedback loop,Factor XI is component of a positive feedback loop,
Thrombin activates Factor XI (along with V, VIII,Thrombin activates Factor XI (along with V, VIII,
and XIII), which generates more thrombin.and XIII), which generates more thrombin.
Results in augmentation of fibrin generation.Results in augmentation of fibrin generation.
Deficiencies not as sevee as VIII, IX, but moreDeficiencies not as sevee as VIII, IX, but more
clinically relevant than XII, Prekallikrein, Highclinically relevant than XII, Prekallikrein, High
Molecular Weight Kininogen.Molecular Weight Kininogen.
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29. VITAMIN K DEPENDENTVITAMIN K DEPENDENT
CARBOXYLASECARBOXYLASE
Post-translational modificationPost-translational modification
Factors II, VII, IX, X;Factors II, VII, IX, X;
– proteins C & Sproteins C & S
Converts several glutamic acidConverts several glutamic acid
residues to γ-carboxyglutamic acidresidues to γ-carboxyglutamic acid
Confers calcium binding and lipidConfers calcium binding and lipid
binding on these proteins.binding on these proteins.
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30. CARBOXYGLUTAMIC ACIDCARBOXYGLUTAMIC ACID
-carboxy Glu
COO-
COO-
COO-
CH
CH2
CHNH3
+
COO-
COO-
CH2
CH2
CHNH3
+
Glu
O2,CO2
Vit K
Carboxylase
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31. Vitamin K MediatedVitamin K Mediated
γγ-Carboxylation of Glutamic Acid-Carboxylation of Glutamic Acid
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32. Vitamin K-Dependent FactorsVitamin K-Dependent Factors
Factors II (Prothrombin), VII, IX, XFactors II (Prothrombin), VII, IX, X
Protein C, Protein SProtein C, Protein S
All are enzymes, except protein S.All are enzymes, except protein S.
γγ-Carboxylation of Glutamic Acid allows-Carboxylation of Glutamic Acid allows
for binding to calcium, and complexfor binding to calcium, and complex
formation.formation.
While both procoagulants andWhile both procoagulants and
anticoagulants are affected, the net effect ofanticoagulants are affected, the net effect of
vitamin K deficiency or antagonism isvitamin K deficiency or antagonism is
anticoagulation.anticoagulation.
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33. Hemostatic BalanceHemostatic Balance
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34. Endothelial Cell-DependentEndothelial Cell-Dependent
Anticoagulant ProcessesAnticoagulant Processes
Heparan Sulfate: AT IIIHeparan Sulfate: AT III
Thrombomodulin: Protein C: Protein SThrombomodulin: Protein C: Protein S
Tissue Factor Pathway InhibitorTissue Factor Pathway Inhibitor
ADPase (CD39)ADPase (CD39)
Nitric OxideNitric Oxide
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35. Heparan:Antithrombin IIIHeparan:Antithrombin III
Deficiency first described in 1965.Deficiency first described in 1965.
– (Egeberg O. Inherited antithrombin III deficiency causing(Egeberg O. Inherited antithrombin III deficiency causing
thrombophilia.thrombophilia. Thromb Diath HaemorrhThromb Diath Haemorrh 13:516-30, 1965)13:516-30, 1965)
AT III neutralizes the active enzymes in the coagulationAT III neutralizes the active enzymes in the coagulation
system.system.
Dominant Inheritance.Dominant Inheritance. 35

36. Antithrombin IIIAntithrombin III
Antithrombin III (Antithrombin)Antithrombin III (Antithrombin)
When heparan sulfate (on endothelial cells) orWhen heparan sulfate (on endothelial cells) or
heparin (mast cells, pharmaceutical) binds to ATheparin (mast cells, pharmaceutical) binds to AT
III, the AT III undergoes a conformational changeIII, the AT III undergoes a conformational change
and binds to the active enzymes of the clottingand binds to the active enzymes of the clotting
cascade.cascade.
Thrombin (IIa), IXa, Xa, XIa are inhibited byThrombin (IIa), IXa, Xa, XIa are inhibited by
Heparin/Heparan:ATIII.Heparin/Heparan:ATIII.
– Factor VIIa is resistant to AT III.Factor VIIa is resistant to AT III.
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37. Protein C/Protein S SystemProtein C/Protein S System
Constituents;Constituents;
– Protein CProtein C
– Protein SProtein S
– ThrombomodulinThrombomodulin
– Endothelial cell protein C receptorEndothelial cell protein C receptor
(EPCR(EPCR
Activated Protein C (WithActivated Protein C (With
cofactor Protein S) inactivatescofactor Protein S) inactivates
Va and VIIIa, the cofactors ofVa and VIIIa, the cofactors of
the cascadethe cascade
– (Probable role in augmenting(Probable role in augmenting
fibrinolysis.)fibrinolysis.)
EPCR localizes Protein C/Ca toEPCR localizes Protein C/Ca to
endothelial cell surface.endothelial cell surface.
– May have role in sepsis.May have role in sepsis.
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38. Fibrinolytic PathwayFibrinolytic Pathway
Plasminogen;Plasminogen;
– Activated to Plasmin (a serine proteinase)Activated to Plasmin (a serine proteinase)
– Plasmin proteolyzes fibrin and fibrinogenPlasmin proteolyzes fibrin and fibrinogen
Plasminogen Activators;Plasminogen Activators;
– t-PA (Tissue-Plasminogen Activator)t-PA (Tissue-Plasminogen Activator)
• Localizes to fibrin clotLocalizes to fibrin clot
– u-PA (Urokinase-Plasminogen Activator)u-PA (Urokinase-Plasminogen Activator)
• Localizes to cell membrane uPA receptor.Localizes to cell membrane uPA receptor.
– Released by endothelial cells.Released by endothelial cells.
Inhibitors/SerpinsInhibitors/Serpins
– PAI-1, PAI-2; Plasminogen Activator InhibitorsPAI-1, PAI-2; Plasminogen Activator Inhibitors
αα2-Antiplasmin.2-Antiplasmin.
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39. Fibrinolytic System ConstituentsFibrinolytic System Constituents
39

40. 40

41. 41

42. 42

43. 43http://thrombin.nl/files/img/knowhow2/thromb2.jpg