university medical center hamburg-eppendorf
TRANSCRIPT
Targeting the Contact Phase – potential for betteranticoagulants?
Thomas RennéInstitute for Clinical Chemistry and Laboratory Medicine
University Medical Center Hamburg-Eppendorf
The contact pathway
ThrombocytesEndothelial cells Cancer CellsLeukocytes
PKHK
Bradykinin
HKFXII
FXI
B2R
Signalling cascades
Coagulation
FXII
Renné et al, Blood (2018)
ActivatorInflammation
Thromboembolic disease
MI
DVT/PE
stroke
The plasma coagulation system
TF
TFFVII
--
FXII
FXI
Fibrin
Thrombin
ContactInjury
aPTT
5 billionaPTT assays
annually
Ratnoff & Colopy, J Clin Invest (1955)
FXII deficiency - normal haemostasis
John Hageman
TF
TFFVII
FXII
FXI
Fibrin
Thrombin
ContactInjury
FXII has no function in coagulation ?
Naito & Fujikawa, J Biol Chem (1981); Gailani & Broze, Science (1981)
aPTTprolonged
20
40
60
80
aPTT [s]
WT + Heparin
0
300
600
900
1200
> 1200
bleeding time [s]
WT + Heparin
WT FXII-/- FXII-/-
FXII-/- mice have a prolonged aPTT butnormal haemostasis
Pauer et al, Thromb Haemost (2004)
WT
Renné et al, J Exp Med (2005); Kleinschnitz et al, J Exp Med (2006)
Defective thrombosis in FXII-/-micewild-type
FXII-/-
0
20
40
60
*
FXI-/-wt
isch
emic
volu
me
[mm
3 ]
FXI-/-wt FXII-/-
+ + +- - -
fibrin
Impaired pathological fibrin formation in FXI-/-mice
fibrin GP Ib merge
Targeting FXII activity
Antibody 3F7 (3F12) selectively blocks FXII activity
ECMO: Extra Corporeal Membrane Oxygenation
Highly thrombogenic
Needs anticoagulation
Targeting FXIIa provides thromboprotection in ECMO
Saline
3F7
Heparin
D Pressure[mm Hg]
Larsson et al, Science Trans Med (2014)
Heparin
Bleeding timeskin [sec]
Blood losscuticle [ml/10 min]
300
600
NaCl0
3F7
2,5
5,0
0HeparinNaCl 3F7
Targeting FXII activity does not interfere with haemostasis
Targeting FXII in baboons and FXI activity in rabbitsprotects against thrombosis sparing hemostasis
David et al, Science Transl Med (2016)Matafonov et al, Blood (2014)
Effect of FXI-ASO on the Coagulation System.
Büller et al, N Engl J Med (2014)
FXI knockdown using ASO provides safe anticoagulationin patients after knee surgery
Thrombosis
Maas & Renné, Blood (2018)
HaemostasisBleeding
Thrombus
Sealing ofwounds
FXII-drivencoagulation
Revision of the classical coagulation balance
FXII-driven coagulation in thrombosis
Haemostasis Thombosis
Kenne et al, J Int Med (2015)
FXII-/-WT
accelerated clotting time [x-fold]
4
3
2
platelet activator +-+-
5
Castaldi et al, Nature (1965); Walsh & Griffin, Blood (1981); Johne et al, BC (2006); Bäck et al, BBRC (2010)
Activated platelet-driven coagulation is defective inFXII-deficient plasma
• glass• silica• dextran sulfate• kaolin
• DNA/RNA• collagen• lipopolysaccaride• glycosaminoglycans
artificial natural
FXII contact activators
Maas et al, Sem Thromb Hemost (2011)
throm
bin
+
+ p
hosp
hatas
e
[bp]
2550
100200
w/o trap6
throm
bin
Platelet polyphosphate (polyP)
Müller, Mutch et al, Cell (2009)
Platelet polyP initiates FXII-driven coagulation
thrombin [nM]200
100
FVIIai + polyP
0 10 20 30 40time [min]
+ 4.8 µg/ml
+ 1.2 µg/ml
w/o
FXII-def.0
thrombin
TF FVIIa
FVIIai/ASISFXIIa
FXIa
Müller, Mutch et al, Cell (2009)
2/15 10/1513/15
WT WT +PGE1
FXII-/-
FXII-/-mice are protected from polyP- and activated platelet-driven thrombosis
Purified platelet polyP Activated platelets
Inherited deficiency in platelet polyP protectsIp6K1-/-mice from thrombosis
Gosh et al, Blood (2013)
Platelet polyP promotes thrombosis
Modified from Caen & Wu, J Thromb Haemost (2010)Walker et al, Br J Haematol (2007)
n
Activated platelets release polyP into the supernatant…
Labberton et al, Nat Commun (2016)
polyP[nM Pi/108 platelets]
…however the majority of polyP is retained at the platelet surface
Labberton et al, Nat Commun (2016)
polyP[nM Pi/108 platelets]
Insoluble polyP on platelet surfaces
Verhoef et al, Blood (2017)
polyPExtracellular polyPTotal polyP
polyP
Wijeyewickrema et al, Blood (2016)
polyP
solublesupernatant
insolublecell surface
Platelets have two pools of polyP: long chain/insoluble and short chain/soluble polymers
Verhoef et al, Blood (2017)
Platelet polyP form Ca2+-rich microparticles
DensityVerhoef et al, Blood (2017)
Chain-lengthindependent
Disassembly of platelet polyP microparticles impairstheir FXII activating potential
+EDTA
Surface-associated(insoluble)
Verhoef et al, Blood (2017)
soluble
FXII
activ
ity
Platelet-derived polyP microparticles drive thrombosisin a FXII-dependent manner
Nickel et al., ATVB (2017)
Hemostasis Thrombosis
Analysis of polyP nanoparticles on platelet surfaces
Labberton et al, Flow Cytometry (2017)
Targeting the polyP/contact pathway in
cancer-associated thrombosis
Prostate cancer exposes polyP that activates FXII
polyP
FXIIa
overlay
+ Ph
osph
atas
eProstate cancer
polyP
Fibrin
Cancer patient plasmacells MP tissue
Nickel et al, Blood (2015)
Targeting FXII interferes with prostate cancer-triggered PE
The polyP/contact pathway contributes to thrombosis in cancer
Nickel et al, Thromb Res (2016)
Targeting polyP
Degradation of polyP ablates their procoagulat activity
E. coli exopolyphosphatase(PPX)
Targeting polyP blocks procoagulant platelet activity
FXII-/-WT
accelerated clotting time [x-fold]
3
2
1
platelet activator + ++-
4
WT +PPX
Labberton et al, Nat Commun (2016)
Targeting polyP interferes with platelet-driven thrombosis without affecting hemostasis
Labberton et al, Nat Commun (2016)
Regulation of platelet polyP
Pi polyP
Systems biology identified XPR1 as the majorPi exporter in platelets
Mailer, Allend et al, (in revision 2020)
Platelet Xenotropic and polytropic retrovirus receptor 1 (XPR1)
Merge
XPR1
Bright field
Mailer, Allende et al, BLOOD (2020)
Pi
intracellular
extracellular
SPX
PDZbm
N
C
Receptordomain
retrovirus
Subcellular localization of XPR1 in platelets
XPR1 expression inversely regulates polyP in cellsMeg01HEK293
XPR1
40
pCHIX-XPR1 (μg)
84210.5Mock
70
MW(kDa)
VASP
Mock
70
2 4 8 16 32
pCHIX-XPR1 (μg)
40
XPR1
VASP
Mw(kDa)
overexpression
Knock-down
Pharmacology: Recombinant XPR1 inhibitors
XVDL
259XLV-Env
1
6xHis RBD
TM
554478
CT
644
RBD
PRL
Mw(kDa)
35
25
40
PVDL XVDL XVDLPVDLPRL
35
25
40
Mw(kDa)
PVDL
262PLV-Env
1
6xHis RBD
TM
620439
CT
641
RBD
Mailer, Allende et al, BLOOD (2020)
active inhibitor inactive control
Inhibition of XPR1 increases soluble and insoluble polyP
soluble
insoluble
total
Targeting XPR1 increases procoagulant platelet activity
Targeting XPR1 increases thrombosis under flow
PPX 0 2 20 200 PPX 0 2 20 200
arterial venous
Targeting XPR1 increases coagulation and platelet polyP
Fibrin GPIb MergeBright field
0XV
DL
(μg/
ml)
Fibrin GPIb MergeBright field
020
0
0XV
DL
μg/m
l 020
0
polyPBright fieldpolyPBright field
200
200
XVD
L (μ
g/m
l)XV
DL
(μg/
ml)
arterial venous
Platelet-specific ablation of XPR1 in mice
Platelet XPR1 knockout PolyP[mM Pi/108 pl]
MW(kDa)70 XPR1
Platelets
43 β-actin
Xpr1fl/fl Xpr1fl/fl
Pf4-CreXpr1fl/+
Pf4-Cre
Mailer, Allende et al, BLOOD (2020)
Increased arterial occlusion in platelet XPR deficient mice
Increased platelet-driven venous thrombosis but normal haemostasis in platelet XPR1-deficient mice
XPR1 regulates procoagulant platelet polyP
Graphical abstract of Mailer, Allende et al, BLOOD (2020)
Factor XII as a target for treatment of thrombosis
§ FXII contact activation is essential for thrombosis but FXII is dispensable for haemostasis
§ PolyP is an in vivo FXII contact activator triggers the „intrinsic“ coagulation pathway on platelets and cancer cell surfaces in vivo
§ PolyP forms insoluble Ca2+-rich microparticles that activate FXII in vivoindependently of the chain length of the individual poly
§ Targeting polyP or FXII (or FXI) provides safe thromboprotection(“Safe Anticoagulants“) and provides additional anti-inflammatory activities
§ The Pi exporter XPR1 regulates polyP in platelets (and other cells) suggesting that Pi have a role in thrombosis
Clément Naudin
MarcoHeestermans
• Lynn Butler, Tromsø• Christian Drouet, Grenoble• Tobias Fuchs, Hamburg• Dave Gailani, Nashville• Johan Heemskerk, Maastricht• Christoph Kleinschnitz, Essen• Nigel Key, Chapell Hill• Florian Langer, Hamburg• Nigel Mackman, Chapell Hill• Joost Meijers, Amsterdam• James Morrissey, Ann Arbor• Werner Müller-Esterl, Frankfurt• Nicola Mutch, Aberdeen
Jenny Björkqvist Coen Maas
Anna Sala
Thank you very very much!• Gunnar Nielsson, Stockholm• Benhard Nieswandt, Würzburg• Markus Noethen, Bonn• Kosta Panousis, Melbourne• Klaus Preissner, Giessen• Huge ten Cate, Mastricht• Albert Sickmann, Dortmund• Alvin Schmaier, Cleveland• Henri Spronk, Maastricht• Evi Stavrou, Cleveland• Guido Stoll, Würzburg• Ulrich Walter, Mainz• Walter Wuillemin, Luzern
Katrin Nickel
Special thank to the people who did the work!
Mikel AllendeLinda Labberton Katrin NickelReiner Mailer