U.S. patent application number 11/454615 was filed with the patent office on 2007-01-18 for adamts13-containing compositions having thrombolytic activity.
Invention is credited to Anil Kumar Chauhan, Barbara Plaimauer, Friedrich Scheiflinger, Denisa Wagner.
Application Number | 20070015703 11/454615 |
Document ID | / |
Family ID | 36956096 |
Filed Date | 2007-01-18 |
United States Patent
Application |
20070015703 |
Kind Code |
A1 |
Wagner; Denisa ; et
al. |
January 18, 2007 |
ADAMTS13-containing compositions having thrombolytic activity
Abstract
This invention relates to a pharmaceutical composition having
thrombolytic activity comprising ADAMTS13, and to methods for
treating or preventing a disorder associated with the formation
and/or the presence of one or more thrombus and to methods of
disintegrating one or more thrombus in a patient in need thereof.
Furthermore, the invention relates to the use of a pharmaceutically
effective amount of ADAMTS13 for the preparation of a
pharmaceutical composition for treating or preventing a disorder
associated with the formation or the presence of one or more
thrombus and for disintegrating one or more thrombus in a patient
in need thereof.
Inventors: |
Wagner; Denisa; (Dover,
MA) ; Chauhan; Anil Kumar; (Brookline, MA) ;
Scheiflinger; Friedrich; (Vienna, AT) ; Plaimauer;
Barbara; (Vienna, AT) |
Correspondence
Address: |
BAXTER HEALTHCARE CORPORATION
ONE BAXTER PARKWAY
MAIL STOP DF2-2E
DEERFIELD
IL
60015
US
|
Family ID: |
36956096 |
Appl. No.: |
11/454615 |
Filed: |
June 16, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
60771265 |
Feb 7, 2006 |
|
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60729323 |
Oct 21, 2005 |
|
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60691927 |
Jun 17, 2005 |
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Current U.S.
Class: |
424/94.63 ;
514/1.4; 514/14.9; 514/16.4; 514/17.7 |
Current CPC
Class: |
A61P 7/02 20180101; A61P
9/10 20180101; A61K 38/4886 20130101; C12N 9/6489 20130101; A61K
38/17 20130101 |
Class at
Publication: |
514/012 |
International
Class: |
A61K 38/17 20070101
A61K038/17 |
Claims
1. A pharmaceutical composition having thrombolytic activity,
comprising a pharmaceutically effective amount of ADAMTS13 or a
biologically active derivative thereof.
2. The pharmaceutical composition according to claim 1, wherein
ADAMTS13 is recombinant human ADAMTS13 or a biologically active
derivative thereof.
3. The pharmaceutical composition according to claim 1, wherein the
biologically active derivative is a chimeric molecule comprising
ADAMTS13 or a biologically active derivative thereof and Ig or a
biologically active derivative thereof.
4. The pharmaceutical composition according to claim 1, further
comprising one or more additional active ingredient.
5. The pharmaceutical composition according to claim 4, wherein the
additional active ingredient is selected from the group consisting
of antithrombic agents; agents that stimulate ADAMTS13
production/secretion; agents that inhibit ADAMTS13 degradation;
agents that enhance ADAMTS13 activity; and agents that inhibit
ADAMTS13 clearance from circulation.
6. The pharmaceutical composition according to claim 5, wherein the
anti-thrombotic agent is selected from the group consisting of
anti-platelets, t-PA, aspirin and heparin.
7. A method of treating or preventing a disorder associated with
the formation and/or the presence of one or more thrombus,
comprising the step of administering a composition according to
claim 1 to a patient.
8. A method according to claim 7, wherein the disorder is selected
from the group consisting of hereditary thrombotic thrombocytopenic
purpura (TTP), acquired TTP, arterial thrombosis, acute myocardial
infarction (AMI), stroke, sepsis, disseminated intravascular
coagulation (DIC), and venous thrombosis, such as e.g. deep vein
thrombosis or pulmonary embolism.
9. A method of disintegrating one or more thrombus in a patient in
need thereof, comprising the step of administering a composition
according to claim 1 to said patient.
10. The use of a pharmaceutically effective amount of ADAMTS13 or a
biologically active derivative thereof for the preparation of a
pharmaceutical composition for treating or preventing a disorder
associated with the formation and/or the presence of one or more
thrombus.
11. The use according to claim 10, wherein the disorder is selected
from the group consisting of hereditary thrombotic thrombocytopenic
purpura (TTP), acquired TTP, arterial thrombosis, acute myocardial
infarction (AMI), stroke, sepsis, disseminated intravascular
coagulation (DIC), and venous thrombosis, such as e.g. deep vein
thrombosis or pulmonary embolism.
12. The use of a pharmaceutically effective amount of ADAMTS13 or a
biologically active derivative thereof for the preparation of
pharmaceutical composition for disintegrating one or more thrombus
in a patient in need thereof.
13. The use according to one of claims 10 or 12, wherein the
pharmaceutically effective amount of ADAMTS13 or a biologically
active derivative thereof ranges from 0.1 to 20 mg/kg body weight.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Patent Application
No. 60/691,927, filed Jun. 17, 2005; U.S. Patent Application No.
60/729,323, filed Oct. 21, 2005; and U.S. Application No.
60/771,265, filed Feb. 7, 2006; each of which applications is
hereby incorporated by references in its entirety for all
purposes.
FIELD OF THE INVENTION
[0002] This invention relates to pharmaceutical compositions having
thrombolytic activity comprising a pharmaceutically effective
amount of ADAMTS13, to methods of treating or preventing disorders
associated with the formation and/or the presence of one or more
thrombus as well as to methods for disintegrating one or more
thrombus in a patient in need thereof. Furthermore, the invention
relates to the use of a pharmaceutically effective amount of
ADAMTS13 for the preparation of a pharmaceutical composition for
treating or preventing a disorder associated with the formation
and/or the presence of one or more thrombus and for disintegrating
one or more thrombus in a patient in need thereof.
BACKGROUND OF THE INVENTION
[0003] Thrombotic thrombocytopenic purpura (TTP) is a disorder
characterized by thrombotic microangiopathy, thrombocytopenia and
microvascular thrombosis that can cause various degrees of tissue
ischemia and infarction. Clinically, TTP patients are diagnosed by
symptoms such as thrombocytopenia, schistocytes (fragments of
erythrocytes) and elevated levels of lactate dehydrogenase (Moake J
L. Thrombotic microangiopathies. N Engl J Med. 2002; 347:589-600;
Moake J L. von Willebrand factor, ADAMTS-13, and thrombotic
thrombocytopenic purpura. Semin Hematol. 2004; 41:4-14; Sadler J E,
Moake J L, Miyata T, George J N. Recent advances in thrombotic
thrombocytopenic purpura. Hematology (Am Soc Hematol Educ Program).
2004: 407-423; Sadler J E. New concepts in von Willebrand disease.
Annu Rev Med. 2005; 56:173-191). In 1982, Moake et al. found
unusually large von Willebrand factor (UL-vWF) multimers in the
plasma of the patients with chronic relapsing TTP (Moake J L, Rudy
C K, Troll J H, Weinstein M J, Colannino N M, Azocar J, Seder R H,
Hong S L, Deykin D. Unusually large plasma factor VIII:von
Willebrand factor multimers in chronic relapsing thrombotic
thrombocytopenic purpura. N Engl J Med. 1982; 307:1432-1435). The
link between UL-vWF and TTP gained support with independent
findings by Furlan et al. and Tsai and Lian that most patients
suffering from TTP are deficient in a plasma metalloprotease that
cleaves vWF (Furlan M, Robles R, Solenthaler M, Wassmer M, Sandoz
P, Laemmle B. Deficient activity of von Willebrand factor-cleaving
protease in chronic relapsing thrombotic thrombocytopenic purpura.
Blood. 1997; 89:3097-3103; Tsai H M, Sussman, I I, Ginsburg D,
Lankhof H, Sixma J J, Nagel R L. Proteolytic cleavage of
recombinant type 2A von Willebrand factor mutants R834W and R834Q:
inhibition by doxycycline and by monoclonal antibody VP-1. Blood.
1997; 89:1954-1962; Tsai H M, Lian E C. Antibodies to von
Willebrand factor-cleaving protease in acute thrombotic
thrombocytopenic purpura. N Engl J Med. 1998; 339:1585-1594). The
protease belongs to the ADAMTS family and is designated as ADAMTS13
LA Disintegrin-like And Metalloprotease with Thrombospondin type I
repeats), a 190 kDa glycosylated protein produced predominantly by
the liver (Levy G G, Nichols W C, Lian E C, Foroud T, McClintick J
N, McGee B M, Yang A Y, Siemieniak D R, Stark K R, Gruppo R, Sarode
R, Shurin S B, Chandrasekaran V, Stabler S P, Sabio H, Bouhassira E
E, Upshaw J D, Jr., Ginsburg D, Tsai H M. Mutations in a member of
the ADAMTS gene family cause thrombotic thrombocytopenic purpura.
Nature. 2001; 413:488-494; Fujikawa K, Suzuki H, McMullen B, Chung
D. Purification of human von Willebrand factor-cleaving protease
and its identification as a new member of the metalloproteinase
family. Blood. 2001; 98:1662-1666; Zheng X, Chung D, Takayama T K,
Majerus E M, Sadler J E, Fujikawa K. Structure of von Willebrand
factor-cleaving protease (ADAMTS13), a metalloprotease involved in
thrombotic thrombocytopenic purpura. J Biol Chem. 2001;
276:41059-41063; Soejima K, Mimura N, Hirashima M, Maeda H,
Hamamoto T, Nakagaki T, Nozaki C. A novel human metalloprotease
synthesized in the liver and secreted into the blood: possibly, the
von Willebrand factor-cleaving protease? J Biochem (Tokyo). 2001;
130:475-480; Gerritsen H E, Robles R, Lammle B, Furlan M. Partial
amino acid sequence of purified von Willebrand factor-cleaving
protease. Blood. 2001; 98:1654-1661). Mutations in the ADAMTS13
gene have been shown to cause TTP (Levy G G, Nichols W C, Lian E C,
Foroud T, McClintick J N, McGee B M, Yang A Y, Siemieniak D R,
Stark K R, Gruppo R, Sarode R, Shurin S B, Chandrasekaran V,
Stabler S P, Sabio H, Bouhassira E E, Upshaw J D, Jr., Ginsburg D,
Tsai H M. Mutations in a member of the ADAMTS gene family cause
thrombotic thrombocytopenic purpura. Nature. 2001; 413:488-494).
Idiopathic TTP, often caused by autoantibodies inhibiting ADAMTS-13
activity, is a more common disorder that occurs in adults and older
children and can recur at regular intervals in 11-36% of patients
(Tsai H M, Lian E C. Antibodies to von Willebrand factor-cleaving
protease in acute thrombotic thrombocytopenic purpura. N Engl J
Med. 1998; 339:1585-1594; Furlan M, Lammle B. Deficiency of von
Willebrand factor-cleaving protease in familial and acquired
thrombotic thrombocytopenic purpura. Baillieres Clin Haematol.
1998; 11:509-514). Non neutralizing autoantibodies could also
inhibit ADAMTS activity by inducing clearance from circulation
(Scheiflinger F, Knobl P, Trattner B, Plaimauer B, Mohr G, Dockal
M, Dorner F, Rieger M. Nonneutralizing IgM and IgG antibodies to
von Willebrand factor-cleaving protease (ADAMTS-13) in a patient
with thrombotic thrombocytopenic purpura. Blood. 2003;
102:3241-3243). Plasma ADAMTS13 activity in healthy adults ranges
from 50% to 178% (Moake J L. Thrombotic thrombocytopenic purpura
and the hemolytic uremic syndrome. Arch Pathol Lab Med. 2002;
126:1430-1433). In most patients with familial or acquired TTP,
plasma ADAMTS13 activity is absent or less than 5% of the normal.
Without treatment the mortality rate exceeds 90%, but plasma
therapy has reduced mortality to about 20% (Moake J L. Thrombotic
thrombocytopenic purpura and the hemolytic uremic syndrome. Arch
Pathol Lab Med. 2002; 126:1430-1433).
[0004] vWF synthesized in megakaryocytes and endothelial cells is
stored in platelet .alpha.-granules and Weibel-Palade bodies,
respectively, as ultra large vWF (UL-vWF) 5. Moake J L, Rudy C K,
Troll J H, Weinstein M J, Colannino N M, Azocar J, Seder R H, Hong
S L, Deykin D. Unusually large plasma factor VIII:von Willebrand
factor multimers in chronic relapsing thrombotic thrombocytopenic
purpura. N Engl J Med. 1982; 307:1432-1435; Wagner D D, Olmsted J
B, Marder V J. Immunolocalization of von Willebrand protein in
Weibel-Palade bodies of human endothelial cells. J Cell Biol. 1982;
95:355-360; Wagner D D, Bonfanti R. von Willebrand factor and the
endothelium. Mayo Clin Proc. 1991; 66:621-627; Sporn L A, Marder V
J, Wagner D D. von Willebrand factor released from Weibel-Palade
bodies binds more avidly to extracellular matrix than that secreted
constitutively. Blood. 1987; 69:1531-1534; Tsai H M, Nagel R L,
Hatcher V B, Sussman, I I. Endothelial cell-derived high molecular
weight von Willebrand factor is converted into the plasma multimer
pattern by granulocyte proteases. Biochem Biophys Res Commun. 1989;
158:980-985; Tsai H M, Nagel R L, Hatcher V B, Sussman, I I.
Multimeric composition of endothelial cell-derived von Willebrand
factor. Blood. 1989; 73:2074-2076). Once secreted from endothelial
cells, these UL-vWF multimers are cleaved by ADAMTS13 in
circulation into a series of smaller multimers at specific cleavage
sites within the vWF molecule (Tsai H M, Nagel R L, Hatcher V B,
Sussman, I I. Endothelial cell-derived high molecular weight von
Willebrand factor is converted into the plasma multimer pattern by
granulocyte proteases. Biochem Biophys Res Commun. 1989;
158:980-985; Dent J A, Galbusera M, Ruggeri Z M. Heterogeneity of
plasma von Willebrand factor multimers resulting from proteolysis
of the constituent subunit. J Clin Invest. 1991; 88:774-782; Furlan
M, Robles R, Affolter D, Meyer D, Baillod P, Lammle B. Triplet
structure of von Willebrand factor reflects proteolytic degradation
of high molecular weight multimers. Proc Natl Acad Sci USA. 1993;
90:7503-7507). The protease cleaves at the Tyr842-Met843 bond in
the central A2 domain of the mature vWF subunit and requires zinc
or calcium for activity (Dent J A, Berkowitz S D, Ware J, Kasper C
K, Ruggeri Z M. Identification of a cleavage site directing the
immunochemical detection of molecular abnormalities in type IIA von
Willebrand factor. Proc Natl Acad Sci USA. 1990; 87:6306-6310). vWF
exists in "ball-of-yarn" and filamentous form as seen by electron
microscopy (Slayter H, Loscalzo J, Bockenstedt P, Handin R I.
Native conformation of human von Willebrand protein. Analysis by
electron microscopy and quasi-elastic light scattering. J Biol.
Chem. 1985; 260:8559-8563). Furthermore, atomic force microscopy
confirms that vWF exits in a globular conformation under static
conditions and an unfolded filamentous state after exposure to
shear stress (Siedlecki C A, Lestini B J, Kottke-Marchant K K,
Eppell S J, Wilson D L, Marchant R E. Shear-dependent changes in
the three-dimensional structure of human von Willebrand factor.
Blood. 1996; 88:2939-2950). This could occur also in vivo when one
end of the vWF filament is anchored to a surface.
[0005] UL-vWF multimers, present in Weibel-Palade bodies, when
released by activated endothelial cells bind platelets more tightly
(through GPIb.alpha.) than plasma vWF (27. Arya M, Anvari B, Romo G
M, Cruz M A, Dong J F, McIntire L V, Moake J L, Lopez J A.
Ultralarge multimers of von Willebrand factor form spontaneous
high-strength bonds with the platelet glycoprotein Ib-IX complex:
studies using optical tweezers. Blood. 2002; 99:3971-397). It was
demonstrated in vitro that the platelets align as beads on the
released UL-vWF on the endothelial surface (Dong J F, Moake J L,
Nolasco L, Bernardo A, Arceneaux W, Shrimpton C N, Schade A J,
McIntire L V, Fujikawa K, Lopez J A. ADAMTS-13 rapidly cleaves
newly secreted ultralarge von Willebrand factor multimers on the
endothelial surface under flowing conditions. Blood. 2002;
100:4033-4039). These UL-vWF secreted multimers are anchored to the
cell surface as long stringlike structures. These multimers are
then cleaved by ADAMTS13 as they are secreted from stimulated
endothelial cells (Dong J F, Moake J L, Bernardo A, Fujikawa K,
Ball C, Nolasco L, Lopez J A, Cruz M A. ADAMTS-13 metalloprotease
interacts with the endothelial cell-derived ultra-large von
Willebrand factor. J Biol. Chem. 2003; 278:29633-29639).
[0006] Thrombi of TTP patients consist of little fibrin and mainly
of vWF and platelets, suggesting vWF-mediated platelet aggregation
as a cause of thrombosis (30. Asada Y, Sumiyoshi A, Hayashi T,
Suzumiya J, Kaketani K. Immunohistochemistry of vascular lesion in
thrombotic thrombocytopenic purpura, with special reference to
factor VIII related antigen. Thromb Res. 1985; 38:469-479).
Patients with relapsing TTP have ultra-large multimers in the
plasma. The UL-vWF multimers accumulate over time because the
persistence of the inhibitor (Anti-ADAMTS13 Ab) decreases ADAMTS13
activity. The UL-vWF multimers are hyperactive and unfold as a
result of shear stress causing platelet aggregation, resulting in
intravascular thrombosis (Tsai H M. Von Willebrand factor,
ADAMTS13, and thrombotic thrombocytopenic purpura. J Mol Med. 2002;
80:639-647; Tsai H M. Deficiency of ADAMTS-13 in thrombotic and
thrombocytopenic purpura. J Thromb Haemost. 2003; 1:2038-2040;
discussion 2040-2035).
[0007] It is believed that the presence of hyper-reactive UL-vWF
multimers in the plasma due to ADAMTS13 deficiency could be
associated with an increased risk of arterial thrombosis linked to
coronary heart disease.
[0008] Therefore, a strong need exists for providing new
compositions which are capable of preventing and/or treating
thrombi caused by certain disorders in a patient.
BRIEF SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide a
pharmaceutical composition having thrombolytic activity. The
pharmaceutical composition comprises a pharmaceutically effective
amount of ADAMTS13 or a biologically active derivative thereof, and
optionally one or more pharmaceutically acceptable carrier and/or
diluent. Said composition may also comprise one or more additional
active ingredient. Further, the present invention relates to a
method of treating or preventing a disorder associated with the
formation and/or presence of one or more thrombus and to a method
of disintegrating one or more thrombus in a patient in need
thereof. Examples of disorders associated with the formation and/or
the presence of one or more thrombus are hereditary thrombotic
thrombocytopenic purpura (TTP), acquired TTP, arterial thrombosis,
acute myocardial infarction (AMI), stroke, sepsis, and disseminated
intravascular coagulation (DIC). Accordingly, a pharmaceutically
effective amount of ADAMTS13 or a biologically active derivative
thereof can be used for the preparation of a pharmaceutical
composition for treating or preventing a disorder associated with
the formation and/or the presence of one or more thrombus and for
disintegrating one or more thrombus in a patient in need thereof.
Said pharmaceutically effective amount of ADAMTS13 or a
biologically active derivative thereof may range, for example, from
0.1 to 20 mg/kg body weight.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1. Thrombus formation in microvenules. Mesenteric
venules of approx. 25-30 .mu.m in diameter were visualized after an
incision was made through the abdominal wall to expose the
mesentery of live mice. One min after topical superfusion of
A23187, thrombus formation was observed in Adamts13 -/- mice (n=5).
The arrows indicate the microthrombi. No microthrombi formation was
observed in WT mice treated identically (n=5). Thus, stimulation of
Weibel-Palade body secretion can lead to spontaneous thrombus
formation in Adamts13-/- mice in the absence of vascular
injury.
[0011] FIG. 2. ADAMTS13 inhibitor increases platelets adhesion and
string formation to vessel wall. Fluorescently-labeled platelets
representing approx. 2.5% of total platelets were observed in
mesenteric venules (200-250 .mu.m) of live mice before (baseline)
and after A23187 superfusion. A: Platelets began to adhere to the
endothelium 30 to 45 seconds after superfusion. In WT (infused with
anti-human ADAMTS13 Ab) mice (n=4) more platelets adhered to vessel
wall after 4 min compared to WT (infused with PBS) control (n=4).
Arrowheads indicate the .gtoreq.20 .mu.m strings of platelets
attached at one end to endothelium and waving in blood stream.
Inset time points in lower right corner refer to the time after
superfusion of A23187. Bar shown in the middle panel is (approx.)
50 .mu.m. B: In 5 out of 7 WT mice infused with inhibitor to
ADAMTS13 an approx. 25-35 .mu.m long platelets string anchored to
the vessel wall for up to 10 sec. Inset time points in lower right
corner refer to the time after superfusion of A23187. Bar shown in
the middle panel is (approx.) 25 .mu.m.
[0012] FIG. 3. Thrombus formation in microvenules of WT mice
infused with ADAMTS13 Inhibitor. Mesenteric venules of approx 25-30
.mu.m in diameter were observed. One min after topical superfusion
with A23187, thrombus formation was observed in 4 out of 6 Adamts13
WT mice infused with ADAMTS13 inhibitor. The microthrombi formation
was similar to that seen in Adamts13 -/- mice (FIG. 1). Arrowheads
indicate microthrombi. The microthrombi did not form in WT mice
infused with PBS (n=5).
[0013] FIG. 4. Recombinant ADAMTS13 inhibits platelet strings in
Adamts13 -/- mice. Rhodamin 6G was used to label endogenous
platelets and leukocytes. 1 mM histamine (200 .mu.l) was
administered i.p. 15 mins before surgery and 3 mesenteric venules
of approx. 200-300 .mu.m in diameter were visualized per mouse. A:
No platelet strings are seen in Adamts13 WT mice (n=5). B: Platelet
strings (indicated by arrowheads) are seen in the Adamts13 -/- mice
(n=5). C: The platelet strings could form platelet aggregates in
Adamts13 -/- mice as indicated by arrowhead. D: Infusion of
recombinant human ADAMTS13 protein inhibits the platelets strings
in Adamts13 -/- mice (n=4).
[0014] FIG. 5. Quantitative analysis of platelet adhesion and
thrombi formation in arterioles of WT and Adamts 13 -/- mice. A:
The number of fluorescent platelets deposited per minute was
determined in the interval 2-3 min after injury (total number of
adherent platelets counted in 1 min interval). For statistics and
mean, platelets greater than 100 was considered as 100. Absence of
ADAMTS13 in the plasma clearly influences the early platelet
interaction with the subendothelium. Compared with WT, in Adamts 13
-/- more platelets were deposited on the vessel wall (P<0.05).
B: Thrombus (>30 .mu.m) appeared sooner after injury in Adamts13
-/- mice (mean=6.64.+-.0.93) compared with WT (mean=10.78.+-.0.80)
and this was statistically significant (P<0.005). This
demonstrates that cleavage of UL-vWF multimers by ADAMTS13 delays
thrombus formation. C: The occlusion time when blood flow
completely stopped for 10 sec was determined. Both WT and Adamts13
-/- mice occluded at the site of injury; however in Adamts13 -/-
mice occlusion time was shorter (mean=10.56.+-.0.72) as compared
with WT (mean=16.69.+-.1.25 minutes). The difference was highly
statistically significant (P<0.0005). D: Fluorescently-labeled
platelets representing approx. 2.5% of total platelets were
observed in mesenteric arterioles of live mice after ferric
chloride injury. Blood flow was from left to right. Inset time
points in lower right corner refer to the time after injury. Single
adherent platelets are seen in the arteriole at 4 min after injury
in the WT, whereas a thrombus (approx. 30 .mu.m) can already be
seen in the Adamts13 -/- mouse arteriole at the same time point.
The vessel was occluded at 10 min by a thrombus at the site of
injury in Adamts13 -/- mice, while the WT mouse arteriole remained
opened at that time. Photographs are representative of 10 mice of
each genotype.
[0015] FIG. 6. Inhibition of integrin .alpha.IIb.beta.3 blocks
thrombus formation of ADAMTS13 -/- platelets on collagen under
arterial shear rate conditions. Adamts13 +/+ or Adamts13 -/- whole
blood was perfused for 2 min over a collagen surface at a shear
rate of 1500 s-1. A: Representative images are shown. Upper
panels-untreated whole blood, lower panels-pretreated with blocking
antibody against .alpha.IIb.beta.3 (JON/A). B: Quantification of
the surface area covered by platelets after 2 min of perfusion.
Four frames from different areas of the flow chamber were analyzed
for each blood sample. Data represent the mean percentage of
surface area covered by fluorescent platelets.+-.SEM (n=3-4).
[0016] FIG. 7. Infusion of recombinant human ADAMTS13 inhibits
thrombus growth. Recombinant human ADAMTS13 was infused (i.v.) in
the Adamts13 -/- mice 15 min before the ferric chloride injury. The
occlusion time (blood flow completely stopped for 10 sec) was
determined. A: Five out of 13 Adamts13 -/- mice, infused with
recombinant human ADAMTS13 did not occlude in the arteriole at up
to 40 min of observation time (mean occlusion time=23.80.+-.3.71
min), whereas, all 10 Adamts13 -/- mice infused with recombinant
buffer only occluded (mean occlusion time=11.17.+-.0.87);
(P=0.005). B: Occlusion time in injured arterioles of WT (C57BI/6J)
mice infused either with r-hu ADAMTS13 (mean occlusion
time=27.99.+-.4.72 min) or buffer alone (mean occlusion
time=13.12.+-.0.55 min). C: Representative fluorescent images of
injured arteriole of an Adamts13 -/- mouse treated with r-hu
ADAMTS13 are shown. Arrowheads indicate a disintegrating
thrombus.
[0017] FIG. 8. Infusion of recombinant mouse ADAMTS13 inhibits
thrombus growth in WT mice. Recombinant mouse ADAMTS13 (2.6 mg/kg
mouse) was infused (i.v.) into the WT mice 5 min before the ferric
chloride injury. Four out of nine WT mice infused with recombinant
mouse ADAMTS13 did not occlude the injured arterioles at 40 min of
observation time (mean occlusion time=27.04.+-.3.84 min), whereas
all WT mice infused with buffer occluded (mean occlusion
time=15.15.+-.1.18 min, P=0.006).
[0018] FIG. 9. Table 1: Hemodynamic parameters prior to and after
application of A23187 on venules (FIG. 1); Table 2: Hemodynamic
parameters prior to and after application of ferric chloride on
arterioles (FIG. 5).
DETAILED DESCRIPTION OF THE INVENTION
[0019] One aspect of the present invention relates to a
pharmaceutical composition having thrombolytic activity, comprising
a pharmaceutically effective amount of ADAMTS13 or a biologically
active derivative thereof.
[0020] The term "thrombolytic activity" as used herein means the
disintegration of one or more thrombus. Suitable methods for the
determination of thrombolytic activity are well known in the art.
For example, suitable methods are the determination of the lysis of
a whole blood clot using tPA or streptokinase, or the determination
of the thrombus lysis in vivo.
[0021] The term "disintegration" as used herein includes the
partial or complete disintegration, dissolving, dissolution,
destruction and/or lysis of a thrombus.
[0022] The term "thrombus" as used herein comprises a blood clot,
especially a platelet-comprising blood clot, a microthrombus,
and/or an embolus. Said thrombus may be attached to an arterial or
venous blood vessel or not, and may partially or completely block
the blood flow in an arterial or venous blood vessel.
[0023] The term "biologically active derivative" as used herein
means any polypeptides with substantially the same biological
function as ADAMTS13. The polypeptide sequences of the biologically
active derivatives may comprise deletions, additions and/or
substitution of one or more amino acids whose absence, presence
and/or substitution, respectively, do not have any substantial
negative impact on the biological activity of polypeptide. The
biological activity of said polypeptides may be measured, for
example, by the reduction or delay of platelet adhesion to the
endothelium, the reduction or delay of platelet aggregation, the
reduction or delay of the formation of platelet strings, the
reduction or delay of thrombus formation, the reduction or delay of
thrombus growth, the reduction or delay of vessel occlusion, the
proteolytical cleavage of vWF, and/or the disintegration of
thrombi.
[0024] The terms "ADAMTS13" and "biologically active derivative",
respectively, also include polypeptides obtained via recombinant
DNA technology. The recombinant ADAMTS13 ("rADAMTS13"), e.g.
recombinant human ADAMTS13 ("r-hu-ADAMTS13"), may be produced by
any method known in the art. One specific example is disclosed in
WO 02/42441 which is incorporated herein by reference with respect
to the method of producing recombinant ADAMTS13. This may include
any method known in the art for (i) the production of recombinant
DNA by genetic engineering, e.g. via reverse transcription of RNA
and/or amplification of DNA, (ii) introducing recombinant DNA into
prokaryotic or eukaryotic cells by transfection, i.e. via
electroporation or microinjection, (iii) cultivating said
transformed cells, e.g. in a continous or batchwise manner, (iv)
expressing ADAMTS13, e.g. constitutively or upon induction, and (v)
isolating said ADAMTS13, e.g. from the culture medium or by
harvesting the transformed cells, in order to (vi) obtain
substantially purified recombinant ADAMTS13, e.g. via anion
exchange chromatography or affinity chromatography. The term
"biologically active derivative" includes also chimeric molecules
such as e.g. ADAMTS13 (or a biologically active derivative thereof)
in combination with Ig, in order to improve the
biological/pharmacological properties such as e.g. half life of
ADAMTS13 in the circulation system of a mammal, particularly human.
The Ig could have also the site of binding to an optionally mutated
Fc receptor.
[0025] The rADAMTS13 can be produced by expression in a suitable
prokaryotic or eukaryotic host system characterized by producing a
pharmacologically effective ADAMTS13 molecule. Examples of
eukaryotic cells are mammalian cells, such as CHO, COS, HEK 293,
BHK, SK-Hep, and HepG2. There is no particular limitation to the
reagents or conditions used for producing or isolating ADAMTS13
according to the present invention and any system known in the art
or commercially available can be employed. In one embodiment of the
present invention rADAMTS13 is obtained by methods as described in
the state of the art.
[0026] A wide variety of vectors can be used for the preparation of
the rADAMTS13 and can be selected from eukaryotic and prokaryotic
expression vectors. Examples of vectors for prokaryotic expression
include plasmids such as pRSET, pET, pBAD, etc., wherein the
promoters used in prokaryotic expression vectors include lac, trc,
trp, recA, araBAD, etc. Examples of vectors for eukaryotic
expression include: (i) for expression in yeast, vectors such as
pAO, pPIC, pYES, pMET, using promoters such as AOX1, GAP, GAL1,
AUG1, etc; (ii) for expression in insect cells, vectors such as
pMT, pAc5, pIB, pMIB, pBAC, etc., using promoters such as PH, p10,
MT, Ac5, OpIE2, gp64, polh, etc., and (iii) for expression in
mammalian cells, vectors such as pSVL, pCMV, pRc/RSV, pcDNA3, pBPV,
etc., and vectors derived form viral systems such as vaccinia
virus, adeno-associated viruses, herpes viruses, retroviruses,
etc., using promoters such as CMV, SV40, EF-1, UbC, RSV, ADV, BPV,
and .beta.-actin.
[0027] Optionally, the pharmaceutical composition of the present
invention also comprises one or more pharmaceutically acceptable
carrier and/or diluent.
[0028] The pharmaceutical composition of the present invention may
also comprise one or more additional active ingredients such as
e.g. anti-thrombotic agents, agents that stimulate ADAMTS13
production/secretion by the treated patient/individual, agents that
inhibit the degradation of ADAMTS13 and thus prolonging its half
life, agents that enhance ADAMTS13 activity (for example by binding
to ADAMTS13, thereby inducing an activating conformational change),
or agents that inhibit ADAMTS13 clearance from circulation, thereby
increasing its plasma concentration. Examples of anti-thrombotic
agents include anti-platelets, t-PA, aspirin and heparin.
[0029] The present invention further relates to a method of
treating or preventing a disorder associated with the formation
and/or the presence of one or more thrombus, comprising the step of
administering a composition according to the invention to a
patient. Said disorder may be due to hereditary defects,
inflammatory diseases, stroke or septic conditions. Examples of
disorders associated with the formation and/or the presence of one
or more thrombus are hereditary thrombotic thrombocytopenic purpura
(TTP), acquired TTP, arterial thrombosis, acute myocardial
infarction (AMI), stroke, sepsis, disseminated intravascular
coagulation (DIC), and venous thrombosis, such as e.g. deep vein
thrombosis or pulmonary embolism.
[0030] Another aspect of the present invention relates to a method
of disintegrating one or more thrombus in a patient, comprising the
step of administering a composition according to the present
invention to said patient.
[0031] The route of administration of the composition of the
present invention does not exhibit a specific limitation and can
be, for example, subcutaneous or intravenous. The term "patient" as
used in the present invention includes mammals, particularly
human.
[0032] Furthermore, the present invention relates to the use of a
pharmaceutically effective amount of ADAMTS13 or a biologically
active derivative thereof for the preparation of a pharmaceutical
composition for treating or preventing a disorder associated with
the formation and/or the presence of one or more thrombus.
[0033] Another aspect of the present invention is the use of a
pharmaceutically effective amount of ADAMTS13 or a biologically
active derivative thereof for the preparation of a pharmaceutical
composition for disintegrating one or more thrombus in a patient in
need thereof.
[0034] The pharmaceutically effective amount of ADAMTS13 or a
biologically active derivative thereof may range, for example, from
0.1 to 20 mg/kg body weight.
[0035] The present invention will be further illustrated in the
following examples, without any limitation thereto.
EXAMPLES
Example 1
Endothelial Activation Results in Thrombi Formation in Microvenules
of Adamts 13 -/- Mice
[0036] More platelet sticking/translocating in venules (200-250
.mu.m) activated with calcium ionophore A23187 (a secretagouge of
Weibel-Palade bodies) at low shear rate (approx. 100 s.sup.-1) in
Adamts13 -/- mice has been observed compared with WT. It was
investigated whether activation of microvenule endothelium by
A23187 could result in platelet aggregation resulting in thrombus
formation. A23187 does not denude the endothelium (Andre P, Denis C
V, Ware J, Saffaripour S, Hynes R O, Ruggeri Z M, Wagner D D.
Platelets adhere to and translocate on von Willebrand factor
presented by endothelium in stimulated veins. Blood. 2000;
96:3322-3328). The shear rate (200-250 s.sup.-1) and diameter of
all the venules (25-30 .mu.m) studied were similar for Adamts13 -/-
and WT mice (Table 1). In the microvenules of Adamts13 -/- mice, 45
sec to 1 min after topical superfusion of A23187, platelet
aggregation resulted in thrombus formation was observed (FIG. 1).
The thrombi were unstable and flushed away in the blood stream
leading to frequent embolization causing downstream occlusion.
However, the occlusion lasted only 3-4 seconds and the venule
reopened afterwards. Thrombus formation was no longer seen at the
site of stimulation 2 min after A23187 superfusion. In WT mice
treated identically, strings of platelets and very small platelet
aggregates could be seen attached to the endothelium for 1 sec, but
this did not result in thrombus formation. Arterioles running
parallel to the venules in Adamts13 -/- or WT mice did not show any
platelet aggregation or thrombus formation. No platelet strings
could be observed in the arterioles. These observations demonstrate
that ADAMTS13 inhibits platelet aggregation and thus prevents
thrombus formation in the microvenules.
Example 2
An Antibody to ADAMTS13 Induces Formation of Platelets Strings in
Venules of WT Mice
[0037] Previous studies have shown that most patients suffering
from the acquired form of TTP have autoimmune inhibitors to
ADAMTS13 (Tsai H M, Lian E C. Antibodies to von Willebrand
factor-cleaving protease in acute thrombotic thrombocytopenic
purpura. N Engl J Med. 1998; 339:1585-1594; Furlan M, Robles R,
Galbusera M, Remuzzi G, Kyrle P A, Brenner B, Krause M, Scharrer I,
Aumann V, Mittler U, Solenthaler M, Lammle B. von Willebrand
factor-cleaving protease in thrombotic thrombocytopenic purpura and
the hemolytic-uremic syndrome. N Engl J Med. 1998; 339:1578-1584).
Polyclonal anti-human ADAMTS13 Ab (dissolved in PBS) was infused in
WT mice 2 hr before the surgery. After topical superfusion of
A23187 of both control mice (infused with PBS) and mice infused
with Anti-ADAMTS13 Ab, many platelets stuck/translocated on the
endothelium, reaching a peak of platelet adhesion between 45 sec to
1 min that progressively decreased with time. However, more
platelet sticking was observed 4 min after the A23187 application
in the Ab-infused WT as compared with control (FIG. 2A). The
phenomenon observed was similar to Adamts13 -/-. Strings of
platelets varying from 20-40 .mu.m attached at one end to the
endothelium and waving in the blood stream were observed. Strings
of platelets were either not seen or were very short lived (less
than 2 sec) in the mice injected with PBS or control Ig. In WT mice
on a genetic background marked by elevated vWF levels (CASA/Rk),
treated with inhibitory antibody, the strings of platelets were
even longer (varying from 30-60 .mu.m) indicating that these were
formed primarily by vWF polymers. (In some mice, these platelet
strings anchored to the endothelium for up to 10 sec (FIG. 2B) and
then were washed away.)
Example 3
ADAMTS13 Inhibitor Results in Thrombi Formation in Microvenules in
WT Mice
[0038] In WT mice, infused with anti-human ADAMTS13-Ab 2 hours
before surgical preparation, microthrombi formed on the vessel wall
45 sec to 1 min after topical superfusion of A23187 in 4 out of 6
mice (FIG. 3). The microthrombi appearance were similar to those
seen in the Adamts13 -/- mice (FIG. 1). Then, the inhibitory
antibody was infused in the WT mice on a C57BL/6 background. In
three out of 5 mice microthrombi formed. In control WT mice, minute
platelet aggregates could be seen attached to the endothelium but
did not result in thrombus formation (n=3).
Example 4
Histamine Induces Platelets Strings in the Venules of Adamts13 -/-
Mice, Whereas, Recombinant ADAMTS13 Inhibits the Formation
[0039] Histamine produced during inflammation is a secretagouge of
Weibel-Palade bodies and stimulates the endothelium. Endogenous
platelets were labeled by infusing Rhodamine 6G i.v. prior to
surgery. One mM (200 .mu.l) histamine was injected i.p. 15 min
before the surgical preparation in the Adamts13 -/- (n=5) and WT
(n=5) mice and venules at a shear rate of approx. 100 s.sup.-1 were
visualized. In the WT, strings of platelets were not seen or were
short lived (less than 5 sec, FIG. 4A), whereas in the Adamts13 -/-
platelet strings varying from 20-100 .mu.m could be seen (FIG. 4B)
anchored to the endothelium for about a minute. In some mice, the
platelet strings anchored to the endothelium from 2 to 5 min. Some
strings appeared to coalesce forming aggregates (FIG. 4C) that were
later released into the blood stream. Infusion of recombinant human
ADAMTS13 (r-hu ADAMTS13) protein in the Adamts13 -/- mice (n=4, 3
venules per mouse) inhibited platelet strings in all the 12 venules
examined (FIG. 4D), thus demonstrating the activity of ADAMTS13 at
low shear.
Example 5
Platelet Binding to Sub Endothelium is Increased in Adamts13 -/-
Mice
[0040] Ferric chloride (FeCl.sub.3) injury leads to
deendothelization and exposes sub endothelium (Ni H, Denis C V,
Subbarao S, Degen J L, Sato T N, Hynes R O, Wagner D D. Persistence
of platelet thrombus formation in arterioles of mice lacking both
von Willebrand factor and fibrinogen. J Clin Invest. 2000;
106:385-392). Platelet subendothelial interactions after injury at
arterial shear are initiated by GPIb-vWF interaction and then
propagated by other receptors (Ni H, Denis C V, Subbarao S, Degen J
L, Sato T N, Hynes R O, Wagner D D. Persistence of platelet
thrombus formation in arterioles of mice lacking both von
Willebrand factor and fibrinogen. J Clin Invest. 2000;
106:385-392). In both WT and Adamts13 -/- mice, platelet-vessel
wall interaction started rapidly after ferric chloride application
to the arteriole. The number of animals in which more than 100
platelets were deposited 2-3 min after injury was higher in
Adamts13 -/- mice (FIG. 5A). In the Adamts13 -/-, 7 out of 12 mice
showed greater than 100 platelets deposited on the vessel wall,
compared to 3 of 10 in the WT mice. The results were statistically
significant (P<0.05, FIG. 5A).
Example 6
Accelerated Thrombus Formation in Injured Arterioles of Adamts 13
-/- Mice
[0041] vWF present in the plasma is either constitutively
synthesized by endothelial cells or is secreted in the form of
unusually large multimers from the platelet .alpha.-granules and
endothelial Weibel-Palade bodies upon activation. UL-vWF is the
most adhesive and reactive form of vWF and may lead to platelet
aggregation resulting in a thrombus if not processed by ADAMTS13.
In the ferric chloride thrombosis model in the Adamts13 -/- mice,
thrombi grew faster as thrombi greater than 30 .mu.m were seen at
6.64.+-.0.93 min compared to 10.78.+-.0.80 min in the WT mice and
the results were statistically significant (P<0.005, FIG. 5B).
The thrombi grew to occlusive size in 10.56.+-.0.72 min in Adamts13
-/-, whereas in WT still the vessels were open (P<0.0005, FIGS.
5C and 5D). In the WT, the mean vessel occlusion time was
16.69.+-.1.25 after injury (P<0.0005). All the vessels occluded
at the site of injury. The shear rate and diameter of arterioles
studied were similar for Adamts13 -/- and WT mice (Table 2). Of
note, in arterioles of Adamts13 -/- mice the mean time for
formation of thrombus (>30 .mu.m) as well as mean occlusion time
were less than for any individual WT mouse (FIGS. 5B and 5C). It
has been observed that emboli (>30 .mu.m) formed in 4 out of 10
(40%) Adamts13 -/- mice whereas only in 2 of 11 (18.2%) WT mice
showed embolization. Thus the Adamts 13 -/- thrombi appeared
slightly less stable than WT. The observed embolization in Adamts13
-/- mice did not lead to downstream occlusion.
Example 7
ADAMTS13-Deficiency Enhances Thrombus Growth in a .alpha.lIb.beta.3
Integrin-Dependent Manner
[0042] In vitro flow chamber studies were performed with whole
blood in the presence or absence of a blocking antibody (JON/A)
against .alpha.IIb.beta.3 (Bergmeier W, Schulte V, Brockhoff G,
Bier U, Zimgibl H, Nieswandt B. Flow cytometric detection of
activated mouse integrin alphaIIbbeta3 with a novel monoclonal
antibody. Cytometry 2002; 48:80-86) (FIG. 6). To quantify the size
of the thrombi, the surface area covered by fluorescently-labeled
platelets was determined. Adamts13 -/- blood formed significantly
larger thrombi than WT when perfused over collagen for 2 minutes at
a shear rate of 1500 s-1 (44.66.+-.3.63% vs. 20.22.+-.3.88%,
P<0.0005), demonstrating again the key role of ADAMTS13 in
limiting thrombus growth. In the presence of the blocking antibody
to .alpha.IIb.beta.3, only single platelets adhered to the collagen
surface and thrombus formation was completely inhibited in both the
WT and Adamts13 -/- blood (3.01.+-.0.97% vs. 2.82.+-.0.39%,
P>0.05). In addition, it was tested whether infusion of ADAMTS13
inhibitory antibody into beta3 integrin-deficient mice
(Hodivala-Dilke K M, McHugh K P, Tsakiris D A, Rayburn H, Crowley
D, Ullman-Cullere M, Ross F P, Coller B S, Teitelbaum S, Hynes R O.
Beta3-integrin-deficient mice are a model for Glanzmann
thrombasthenia showing placental defects and reduced survival J
Clin Invest 1999; 103:229-238) would induce thrombus formation
after ferric chloride injury. In injured arterioles of beta3 -/-
mice (3 animals were evaluated) no thrombi could be detected
despite the presence of the anti-ADAMTS13 antibody (not shown).
Taken together these results indicate that, at the arterial shear
rates, ultralarge vWF enhances thrombus growth in a
.alpha.IIb.beta.3-dependent manner.
Example 8
Infusion of Recombinant Human ADAMTS13 in Adamts13 -/- or WT
(C57BL/6J) Mice Inhibits Thrombus Growth by Destabilizing the
Platelet Aggregate or Thrombus
[0043] Cleavage of the vWF subunit into proteolytic fragments by
recombinant human ADAMTS13 (r-hu ADAMTS13) has been shown in vitro
(Plaimauer B, Zimmermann K, Volkel D, Antoine G, Kerschbaumer R,
Jenab P, Furlan M, Gerritsen H, Lammle B, Schwarz H P, Scheiflinger
F. Cloning, expression, and functional characterization of the von
Willebrand factor-cleaving protease (ADAMTS13). Blood. 2002;
100:3626-3632). It has been demonstrated that r-hu ADAMTS13
corrects the vWF cleavage defect in hereditary TTP plasma (Antoine
G, Zimmermann K, Plaimauer B, Grillowitzer M, Studt J D, Laemmle B,
Scheiflinger F. ADAMTS13 gene defects in two brothers with
constitutional thrombotic thrombocytopenic purpura. Br J Haematol
2003; 120:821-824). Since accelerated growth of thrombi in Adamts13
-/- mice has been observed, it is hypothesized that ADAMTS13
negatively modulates thrombus growth and therefore infusion of r-hu
ADAMTS-13 in Adamts 13 -/- mice could delay thrombus formation. The
concentration of the circulating human protein was approximately
8.8 U/ml 17 min after infusion and 1.1 U/ml 53 min after infusion
of r-hu ADAMTS13 into Adamts 13 -/- mice. These times correspond
approximately to the onset of ferric chloride injury and the
termination of the experiment. In 5 out of 13 Adamts13 -/- mice
infused with r-hu ADAMTS13, injured arterioles did not occlude for
up to 40 min when the experiment was terminated (FIG. 7A). The
effect of the infused r-hu ADAMTS13 was more than that of
endogenous ADAMTS13 in WT mice as in this injury model all WT
vessels occluded at less than 24 min (FIG. 5C). The mean occlusion
time was significantly prolonged in comparison with the control
mice infused with buffer (P<0.0005). In all mice whose
arterioles did not occlude, thrombi did form but were unstable and
disintegrated (FIG. 7C). This phenomenon of thrombi formation and
disintegration was present during the entire period of observation.
The infusion of r-hu ADAMTS13 prior to injury in WT mice (C57BI/6J)
caused significant delay in occlusion time with half of the
arterioles not occluding by 40 min while all arterioles of WT mice
infused with vehicle occluded by 15 min (FIG. 7 B, P<0.008).
Thus, ADAMTS13 appears to have a significant anti-thrombotic
potential even in WT mice with normal levels of endogenous ADAMTS13
protein.
Example 9
Infusion of Recombinant Mouse ADAMTS13 Inhibits Thrombus Growth in
WT Mice
[0044] r-mouse ADAMTS13 (2.6 mg/kg mouse) was infused (i.v.) into
the WT mice 5 min before the ferric chloride injury. A previously
described model was used with slight modifications as described
below. FIG. 8 shows that four out of nine WT mice infused with
r-ADAMTS13 did not occlude the injured arterioles at 40 min of
observation time (mean occlusion time=27.04.+-.3.84 min), whereas
all WT mice infused with buffer occluded (mean occlusion
time=15.15.+-.1.18 min, P=0.006). Western analysis of the plasma
samples taken at the end of the experiment showed that the shorter
occlusion time in some of the mice infused with r-ADAMTS13 (similar
to WT) was due to increased clearance of the recombinant protein.
Thus, mouse ADAMTS13 appears to have the same anti-thrombotic
potential as the human ADAMTS13 in WT mice with normal levels of
endogenous ADAMTS protein.
[0045] These results show that ADAMTS13 has an antithrombotic as
well as thrombolytic activity.
Experimental Procedures
Animals
[0046] Mice used in the examples were siblings obtained from
crosses of Adamts13 +/- mice on C57BL/6J/129Sv background (Motto D
G, Chauhan A K, Zhu G, Homeister J, Lamb C B, Desch K C, Zhang W,
Tsai H M, Wagner D D, Ginsburg D. Shigatoxin triggers thrombotic
thrombocytopenic purpura in genetically susceptible
ADAMTS13-deficient mice. J Clin Invest 2005; 115:2752-2761). The
mice of pure C57BI/6J background were purchased from the Jackson
Laboratory, Bar Harbor, Me. and beta3 integrin -/- mice on Balb/C
bacjground were a gift from Richard Hynes (MIT). The mice used for
intravital microscopy were young mice (approx. 4 weeks old), both
male and female, weighing 14 to 18 grams. Infused platelets were
isolated from 4 to 6 months old mice of the same genotype. Animals
were bred and housed at CBR Institute for Biomedical Research and
all experimental procedures were approved by its Animal Care and
Use Committee.
Materials
[0047] Calcium ionophore A23187 and ferric chloride were from Sigma
Chemicals, St. Louis, Mo.
Blood Sampling and Platelet Preparation
[0048] Blood was harvested from the retro-orbital venous plexus by
puncture and collected in 1.5 ml polypropylene tubes comprising 300
.mu.l of heparin (30 U/ml). Platelet rich plasma (PRP) was obtained
by centrifugation at 1200 rpm for 5 min. The plasma and buffy coat
comprising some RBCs were gently transferred to fresh polypropylene
tubes and recentrifuged at 1200 rpm for 5 min. The PRP was
transferred to fresh tubes comprising 2 .mu.L of PGI.sub.2 (2
.mu.g/ml) and incubated at 37.degree. C. for 5 min. After
centrifugation at 2800 rpm, pellets were resuspended in 1 ml
modified Tyrode's-HEPES buffer (137 mM NaCl, 0.3 mM
Na.sub.2HPO.sub.4, 2 mM KCl, 12 mM NaHCO.sub.3, 5 mM HEPES, 5 mM
glucose, 0.35% BSA) comprising 2 .mu.l of PGI.sub.2 and incubated
at 37.degree. C. for 5 min. The suspended pellet was centrifuged at
2800 rpm for 5 min. In order to remove PGI.sub.2, the washing step
was repeated twice and platelets were fluorescently labeled with
calcein AM 0.25 mg/mL (Molecular Probes, Eugene, Oreg.) for 10 min
at room temperature.
Polyclonal Anti-ADAMTS13 IgG Production and Purification
[0049] Polyclonal rabbit anti-human ADAMTS13 IgG was produced by
Baxter Bioscience, Vienna Austria. The antibody was obtained by
immunization of New Zealand white rabbits with purified r-hu
ADAMTS13, C-terminally tagged with six His residues. Two rabbits
were immunized by injection of 20 .mu.g of r-hu ADAMTS13 (6-His) in
200 .mu.l of complete Freund's adjuvant. The animals were boostered
after two, four and six weeks by injecting 20 .mu.g of r-hu
ADAMTS13 (6-His) in 200 .mu.l of incomplete Freund's adjuvant.
After eight weeks the rabbits were sacrificed and bled. IgG
antibodies were purified by Protein G affinity chromatography
(HiTrap Protein G HP column; Amersham Bioscience, Piscataway, N.J.,
USA) and formulated in PBS.
Thrombosis in Microvenules
[0050] Intravital microscopy was as done as described in Frenette P
S, Johnson R C, Hynes R O, Wagner D D. Platelets roll on stimulated
endothelium in vivo: an interaction mediated by endothelial
P-selectin. Proc Natl Acad Sci USA. 1995; 92:7450-7454. Briefly,
mice were anesthetized with 2.5% tribromoethanol (0.15 ml/10 g) and
an incision was made through the abdominal wall to expose the
mesentery and mesenteric venule of 25 to 30-.mu.m diameter was
studied. Exposed mesentery was kept moist by periodic superfusion
using PBS (without Ca.sup.2+ or Mg.sup.2+) warmed to 37.degree. C.
The mesentery was transluminated with a 12 V, 100 W, DC-stabilized
source. The shear rate was calculated using an optical Doppler
velocity meter as described in Frenette P S, Moyna C, Hartwell D W,
Lowe J B, Hynes R O, Wagner D D. Platelet-endothelial interactions
in inflamed mesenteric venules. Blood. 1998; 91:1318-1324. Venule
was visualized using a Zeiss (Germany) Axiovert 135 inverted
microscope (Objective 10.times. and 32.times.) connected to an SVHS
video recorder (AG-6730; Panasonic, Tokyo, Japan). One venule was
chosen per mouse and filmed for 3 min for the baseline before the
A23187 superfusion (30 .mu.l of a 10 Mmol/L solution) and monitored
for 10 min.
Platelet Adhesion in Large Venules
[0051] Intravital microscopy was done as described above except
mesenteric venules of 200 to 300-.mu.m diameters were studied.
Fluorescent platelets (1.25.times.10.sup.9 platelets/kg) were
infused through the tail vein. One venule per animal was filmed for
3 minutes for the baseline before the A23187 superfusion (30 .mu.l
of a 10 .mu.mol/L solution) and filming continued until after the
platelet sticking and rolling returned to baseline. Purified rabbit
polyclonal anti-human ADAMTS13 antibody (5 mg/kg mouse) was
dissolved in PBS. Control rabbit IgG (Sigma, St. Louis, Mo.) was in
PBS. 200 .mu.l of 1 mM histamine (Sigma) was injected i.p. to
stimulate the endothelium. 100 .mu.l (0.2 mg/ml) of Rhodamine 6G
(Sigma) was injected i.v. to label the endogenous platelets and
leukocytes prior to surgery and imaging.
Thrombosis in Arterioles
[0052] A model described in Ni H, Denis C V, Subbarao S, Degen J L,
Sato T N, Hynes R O, Wagner D D. Persistence of platelet thrombus
formation in arterioles of mice lacking both von Willebrand factor
and fibrinogen. J Clin Invest. 2000; 106:385-392, was used with
slight modifications (Ni H, Denis C V, Subbarao S, Degen J L, Sato
T N, Hynes R O, Wagner D D. Persistence of platelet thrombus
formation in arterioles of mice lacking both von Willebrand factor
and fibrinogen. J Clin Invest. 2000; 106:385-392). Briefly, mice
were anesthetized with 2.5% tribromoethanol (0.15 ml/10 g) and
fluorescent platelets (1.25.times.10.sup.9 platelets/kg) were
infused through the retro-orbital plexus of the eye. An incision
was made through the abdominal wall to expose the mesentery and
arterioles of approx. 100 .mu.m diameters were studied. Exposed
mesentery was kept moist by periodic superfusion using PBS (without
Ca.sup.2+ or Mg.sup.2+) warmed to 37.degree. C. The mesentery was
transluminated and the shear rate was calculated as described
above. Arterioles were visualized using the same microscope
described above, equipped with a 100-W HBO fluorescent lamp source
(Optic Quip, Highland Mills, N.Y.) with a narrow band fluorescein
isothiocyanate filter set (Chroma Technology, Brattleboro, Vt.) and
a silicon-intensified tube camera C2400 (Hamamatsu, Tokyo, Japan).
Whatman paper saturated with ferric chloride (10%) solution was
applied topically which induced vessel injury and denudation of the
endothelium. The paper was removed after 5 min and vessel was
monitored for 40 min after injury or until occlusion. One arteriole
was chosen per mouse.
Quantitative Analysis of Arteriolar Thrombus
[0053] Analysis of the recorded tape was performed blinded to the
genotype. The parameters that were applied to describe the
characteristics of thrombus formation were: (1) Single
platelet-vessel wall interaction within 2-3 min, determined as the
number of fluorescent platelets that deposited on the 250 .mu.m
vessel wall (seen on the video monitor) during 1 min. (2) The time
required for formation of a thrombus larger than 30 .mu.m. (3)
Thrombus stability by determining the number of thrombi of diameter
larger than 30 .mu.m embolizing away from the viewing field before
vessel occlusion. (4) Occlusion time of the vessel, that is, time
required for blood to stop flowing for 10 sec and (5) site of
vessel occlusion, that is, at the site of injury or downstream.
Recombinant Human ADAMTS13 Infusion
[0054] Recombinant human ADAMTS13 has been obtained by the methods
as described in Plaimauer B, Zimmermann K, Volkel D, Antoine G,
Kerschbaumer R, Jenab P, Furlan M, Gerritsen H, Lammle B, Schwarz H
P, and Scheiflinger F. Cloning, expression, and functional
characterization of the von Willebrand factor-cleaving protease
(ADAMTS13). Blood 2002; 100(10):3626-3632. Recombinant human
ADAMTS13 protein was dissolved in 150 mmol NaCl/20 mmol Histidin/2%
Sucrose/0.05% Crillet 4HP (Tween 80), pH 7.4 (Baxter Bioscience,
Vienna, Austria). Recombinant human ADAMTS13 was injected i.v.
(3460 U/kg mouse). Levels of human ADAMTS13 antigen were determined
by a slight modification of the ELISA method described by Rieger
(Rieger M, Kremer Hovinga J A, Konetschny C, Herzog A, Koller L,
Weber A, Remuzzi G, Dockal M, Plaimauer B and Scheiflinger F.
Relation between ADAMTS13 Activity and ADAMTS13 Antigen Levels in
Healthy Donors and Patients with Thrombotic Microangiopathies
(TMA). Thrombosis and Hemostasis 2006; 95(2):212-20) and r-hu
ADAMTS13 activity was determined according to Gerritsen (Gerritsen
H E, Turecek P L, Schwarz H P, Laemmle B, and Furlan M. Assay of
von Willebrand factor (vWF)-cleaving protease based on decreased
collagen binding affinity of degraded vWF: a tool for the diagnosis
of thrombotic thrombocytopenic purpura (TTP). Thromb Haemost 1999;
82:1386-1389). 1 U corresponds to the level of ADAMTS13 activity in
pooled normal human plasma.
Recombinant Mouse ADAMTS13 Infusion
[0055] Recombinant mouse ADAMTS13 has been obtained by the methods
as described in Bruno K, Volkel D, Plaimauer B, Antoine G, Pable S,
Motto D G, Lemmerhirt H L, Dorner F, Zimmermann K, and Scheiflinger
F. Cloning, expression and functional characterization of the
full-length murine ADAMTS-13. J Thromb Haemost 2005;
3(5):1064-1073. Recombinant mouse ADAMTS13 protein was dissolved in
150 mmol NaCl/20 mmol Histidin/2% Sucrose/0.05% Crillet 4HP (Tween
80), pH 7.4 (Baxter Bioscience, Vienna, Austria).
Flow Chamber Studies
[0056] Flow chamber studies were performed as described in
Bergmeier (Bergmeier W, Burger P C, Piffath C L, Hoffmeister K M,
Hartwig J H, Nieswandt B, and Wagner D D. Metalloproteinase
inhibitors improve the recovery and hemostatic function of in
vitro-aged or -injured mouse platelets. Blood 2003; 102:4229-4235).
Briefly, platelets were isolated from heparinized whole blood,
washed in modified Tyrode-HEPES buffer, and labeled with 2.5
.mu.g/mL calcein. Platelet poor whole blood was reconstituted with
labeled platelets before perfusion in a parallel-plate flow chamber
system coated with 100 .mu.g/mL collagen Horm (NYCOMED, Munich,
Germany) for 1 h at RT. Where indicated, samples were pretreated
with 30 .mu.g/ml JON/A (emfret Analytics, Wuerzburg, Germany) for
10 min prior to perfusion. Platelet adhesion was visualized with an
Axiovert 135 inverted microscope (Zeiss). The percentage of surface
area covered by fluorescent platelets was analyzed using NIH Image
1.61 software by an individual blinded to genotypes.
Statistical Analysis
[0057] Results are reported as the mean.+-.SEM. The statistical
significance of the difference between means was assessed by the
Student's t test.
Discussion of the Experimental Results
[0058] The experimental results have defined a key role for
ADAMTS13 in preventing thrombi formation in activated microvenules
and excessive thrombus formation in the injured arterioles of mice.
Using intravital microscopy, it is shown in vivo in ADAMTS13 -/-
mice that activating venules (25-30 .mu.m) results in platelet
aggregation leading to microthrombi formation (FIG. 1).
Microthrombi do not form in the venules of WT mice treated
identically. When released from the activated endothelium, these
microthrombi can travel downstream and cause occlusion elsewhere in
the small capillaries where they cannot pass, thus leading to organ
ischemia. Patients suffering from TTP often have microthrombi that
are formed in the microvasculature of organs: like brain, heart,
pancreas, spleen, kidney and mesentery. Various agents including
viruses, bacterial shiga toxins, drugs such as ticlopidine and
clopidogrel, antibodies and immune complexes can trigger vascular
activation perhaps inducing Weibel-Palade body release. In
arterioles (which have higher shear stress) treated identically
with A23187 no thrombi could be seen. This is because either
Weibel-Palade bodies were not released in these vessels or, more
likely, vWF is washed too quickly from the endothelial surface to
promote platelet adhesion.
[0059] Autoantibodies neutralizing human ADAMTS13 are a major cause
of the acquired type of TTP. Infusion of anti-ADAMTS13 antibody in
the WT mice resulted in prolonged adhesion of platelets to secreted
vWF and platelet string formation on the stimulated endothelium
(FIG. 2A) that was similar to that seen in the Adamts13 -/- mice.
The strings of platelets, varying from approx. 20-70 .mu.m in
length, can be seen anchored to the endothelium (FIG. 2B). Platelet
strings and aggregates were frequently seen in the Adamts13 -/-
mice when challenged with Weibel-Palade body secretagogues such as
histamine, inflammatory cytokine TNF-.alpha. and activated
platelets. Infusion of the r-hu ADAMTS13 protein in the Adamts13
-/- mice challenged with histamine inhibits the platelet strings
formation. These strings are cleaved at the upstream end.
[0060] Activation of microvenules (25 to 30 .mu.m) with A23187
results in platelet aggregates leading to thrombi formation in the
Adamts13 WT mice infused with anti-ADAMTS13-Ab (FIG. 3). However,
these thrombi embolized reapidly, similar to those in the Adamts13
-/- mice. Microthrombi formation can be also induced in the WT mice
on a C57BL/6 background infused with inhibitory antibody. Thus the
mouse infused with anti-ADAMTS 13 Ab is in many aspects a good
model for acquired TTP. In addition, it demonstrates the role of
the ADAMTS13 in preventing platelet aggregation in the
circulation.
[0061] vWF through its receptors, GPIb.alpha. and
.alpha.IIb.beta.3, contributes to platelet function in initiating
platelet aggregation and progression of thrombus formation. The
experimental observations that platelet-endothelial interactions
are prolonged and that the endothelial activation results in
microthrombi in the Adamts13 -/- mice led to the hypothesis that
ADAMTS13 deficiency might accelerate thrombus formation in injured
arterioles. Indeed, the absence of ADAMTS13 promoted all aspects of
thrombus growth. Unexpectedly, even more platelets deposited on the
denuded vessel wall after 2-3 mins of injury in the Adamts13 -/-
mice as compared with WT (FIG. 5A). Since early platelet deposition
in arterioles is vWF dependent, it means that either plasma
ADAMTS13 reduces vWF incorporation into the basement membrane when
it is exposed to blood, or that it digests vWF already present in
the extra-cellular matrix. The rapid thrombus growth and occlusion
in Adamts13 -/- mice indicates that ADAMTS13 might cleave vWF
multimers incorporated in the thrombus.
[0062] It has been suggested that cleavage of VWF domain A2 by
ADAMTS13 is facilitated by the binding of VWF to GPIb.alpha.. Thus,
the VWF-GPIb interaction within the thrombus may negatively
regulate thrombus growth. Thrombus formation under venous and
arterial flow conditions also depends on major integrin
.alpha.IIb.beta.3. The present examples at arteriolar shear rates
show that ADAMTS13 modulates the growing thrombus only when
platelets in the thrombus express an active beta3 integrin. Under
these in vitro and in vivo experimental conditions,
ADAMTS13-deficiency did not promote thrombus growth if the major
platelet integrin was absent or inhibited (FIG. 6).
[0063] In order to inhibit the fast thrombus growth seen in the
ADAMTS13 -/- mice, r-hu ADAMTS13 was infused into Adamts13 -/- and
WT mice prior to injury. The anti-thrombotic effect of the r-hu
ADAMTS13, although highly statistically significant, varied among
the animals (FIGS. 7A and 7B). Some mice did not respond to r-hu
ADAMTS13 treatment. It is possible that in these mice r-hu ADAMTS13
was proteolytically inactivated by thrombin and plasmin produced at
the sites of vascular injury. IL-6 and high amounts of vWF released
after inflammation or injury could also reduce ADAMTS13 activity.
In the vessels which did not occlude, the phenomenon of thrombi
disintegrating and reforming is observed (FIG. 7C). These findings
show that ADAMTS13 have both anti-thrombotic and thrombolytic
activity. A possible mechanism is ADAMTS13 cleaving the UL-vWF
multimers into smaller fragments that are less adhesive or directly
cleaving the vWF molecules bridging platelets in a thrombus as is
the case in cleavage of platelets attached to strings. In vivo,
ADAMTS13 is active at both low venous and high arterial shear
stress conditions. It cleaves platelet strings and regulates
platelet interaction with the "activated" vessel wall in the
venules, prevents thrombi in activated microvenules and modulates
the thrombotic response in injured arterioles.
[0064] Congenital TTP patients are currently treated by plasma
exchange, whereas acquired TTP patients are subjected to
plasmapheresis where autoantibodies are removed from the plasma.
The antithrombotic and thrombolytic effect of ADAMTS13 protein
indicates that besides TTP, e.g. recombinant ADAMTS13 can be used
to treat patients suffering with thrombotic disorders due to
hereditary defects, inflammatory disease, septic conditions, or
venous thrombosis, such as e.g. deep vein thrombosis or pulmonary
embolism. The thrombolytic activity of the ADAMTS13 shows that this
protein can be used in combination with other therapies to
disintegrate thrombi in clogged arteries or after minor stroke.
[0065] In summary, the experimental data show that the
metalloprotease ADAMTS13 negatively regulates thrombosis, which
indicates that the molecule has anti-thrombic activity. Thus, e.g.,
recombinant human ADAMTS13 protein having thrombolytic activity can
be used as a therapeutic agent to treat thrombotic disorders.
[0066] It is understood that the examples and embodiments described
herein are for illustrative purposes only and that various
modifications and changes in light thereof will be suggested to
persons skilled in the art and are to be included within the
purview of this application and are considered to be within the
scope of the appended claims. All publications, patents, and patent
applications cited herein are hereby incorporated by reference in
their entirety for all purposes.
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