TACTIC PROJECT 2: THE ROLE OF FACTOR XI IN TIC

LEAD INVESTIGATOR: SAULIUS BUTENAS (UNIVERSITY OF VERMONT)

CO-INVESTIGATOR: JAMES H MORRISSEY (UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN)

PHILADELPHIA, SEPTEMBER 10, 2014

a

The Coagulation CascadeIntrinsic Pathway

Factor XIIPrekallikrein

HMW Kininogen“Surface”

Factor XIaHMW Kininogen

MembraneCa2+, Zn2+

Intrinsic Tenase

AT-III

AT-III

IIa

XIa

Vai

VIIIai

XIIa

IXa

Extrinsic Pathway

Factor VIIaTissue Factor

MembraneCa2+

Factor IXaFactor VIIIaMembrane

Ca2+

Factor XaFactor Va

MembraneCa2+

ThrombinThrombomodulin

MembraneCa2+

Fibrin Clot Formation

Extrinsic Tenase

Prothrombinase

Cross-LinkedFibrin Clot

Soluble Fibrin Peptides

TFPIAT-III

PAI-1

AT-III

TAFIa

Plasmin

APC

2-AP

AT-III

XIIIa

FibrinIIa

Xa Xa

IXa

TFPIAT-III

Red = EnzymesYellow = Inhibitors

VascularInjury

Tissue Factor

IIaVaVIIIa

FXIa-Initiated Clotting of Whole Blood

5 pM TF 50 pM XIa 10 pM XIa 5 pM XIa 1 pM XIa 0.5 pM XIa 0.1 pM XIa0

125

250

375

500

625

750

Clot

Tim

e (s

)

Initiator Concentration

Assays for FXIa

Clotting and thrombin generation (TGA) assays were developed.

Both assays are based on the response of contact pathway-inhibited (corn trypsin inhibitor; CTI) plasma to the inhibitory anti-FXI monoclonal antibody.

No exogenous initiator of thrombin

generation is added. No thrombin generation/clot formation is

observed in plasma from healthy individuals

Study #1(In collaboration with Dr. M. Park from Mayo Clinic)

Multiple time-points from 98 patients: Burn 34 Blunt 47 Penetrating 17

Clotting assay was used for the quantitation of FXIa

Supported by DoD and PO1 HL46703

Blunt Penetrating Thermal0

20

40

60

80

100

26/48

4/17

16/34

32/48

7/17

24/37

FXIa Activity in Trauma PatientsAdmission Overall

% w

ith

XIa

Acti

vity

≥10% 3rd

Degree

<10% 3rd

Degree

≥30% 2nd + 3rd

Degree

<30% 2nd + 3rd

Degree

ISS Score ≥25

ISS Score <25

AIS Ex-ternal =5

AIS Ex-ternal <5

0

20

40

60

80

100

11/19

5/15

12/17

4/17

13/19

3/15

12/16

4/18

FXIa Activity in Burn Patients%

wit

h XI

a A

ctivi

ty

ISS Score ≥25 ISS Score <25 Head/Neck ≥4 Head/Neck <40

20

40

60

80

100

18/27

8/20

18/27

8/20

FXIa Activity in Blunt Patients%

wit

h XI

a A

ctivi

ty

Blunt Penetrating Thermal0

20

40

60

80

100

3/4

0/1

6/1120/36

4/10

9/203/7

0/2 0/0

FXIa Activity in All PatientsD L T

% w

ith

XIa

Acti

vity

*ISS – injury severity score.**Average ± SD for patients with FXIa ≥ 10 pM. Detectabiliy limit of FXIa in this clotting time-based assay is 10 pM.

S. Butenas, M. Park, K. Mann (unpublished data).

Active Factor XIa at Admission

Injury

ISS* > 25 ISS ≤ 25

XIa

Frequency (pM)** Frequency (pM)

Burn 13/19 (68%) 38±36 3/15 (20%) 47±7

Blunt 19/31 (61%) 39±28 7/16 (44%) 37±26

Penetrating 3/7 (43%) 55±65 1/10 (10%) 160

Conclusion #1

The occurrence of FXIa correlates with the severity of trauma

Study #2 (In collaboration with Dr. J. Shupp from Washington Burn Center)

56 Burn patients 463 time-points Up to 20 time-points per patient from 0 to 504

hours (3 weeks)

Thrombin Generation assay was used for the quantitation of FXIa

Supported by Systems Biology grant

Conclusion #2

Of 56 burn patients analyzed:62% had TF and 100% had FXIa at at least one time-point.

TF activity was observed in 21% and FXIa in 90% time-point samples.

Study #3 (In collaboration with Dr. K. Freeman from FAHC, Burlington VT)

Multiple time-point plasma samples from 66 patients (no burn patients; 187 time-points)

56% of them had TF and 94% had FXIa at at least one time-point.

TF activity was observed in 30% and FXIa in

79% time-point samples.

Thrombin Generation assay was used for the quantitation of FXIa

Supported by Systems Biology grant

Final Conclusions

The majority of trauma patients have circulating FXIa, which correlates with trauma severity.

FXIa concentration over observation time varies in a wide range.

The frequency of FXIa in burn patients is higher than in other trauma patient categories

FXIa could be a potential marker of trauma severity