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ABSTRACT: BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) is characterized by deficient ADAMTS13 activity. Treatment involves plasma exchange (PE). Both fresh-frozen plasma (FFP) and cryosupernatant (CSP) are used, but it remains to be determined which is more effective. STUDY DESIGN AND METHODS: To analyze the interaction between von Willebrand factor (VWF) and ADAMTS13, we used large-pore isoelectric focusing (IEF) analysis followed by detection with anti-ADAMTS13 monoclonal antibody. FFP, CSP, cryoprecipitate (CP), and purified ADAMTS13 were analyzed for their effects on high shear stress-induced platelet aggregation (H-SIPA). RESULTS: IEF analysis of normal plasma revealed three groups of ADAMTS13 bands with pI of 4.9 to 5.6, 5.8 to 6.7, and 7.0 or 7.5. Two band groups (pI 4.9-5.6 and 5.8-6.7) were found in plasma of a patient with Type 3 von Willebrand disease, in which VWF is absent, whereas no bands were found in plasma of a patient with congenital ADAMTS13 deficiency. Mixing these plasmas generated the bands at pI 7.0 or 7.5, representing the VWF-ADAMTS13 complex; these bands were absent in CSP. FFP and purified ADAMTS13 down regulated H-SIPA in a dose-dependent manner. However, CP did not inhibit H-SIPA in the initial phase, and the degree of inhibition at the endpoint was almost indistinguishable from those of the other two plasma products. CONCLUSION: Both plasma products (FFP and CSP) are effective for PE in TTP patients. However, CSP may be more favorable, because it has lower levels of VWF and almost normal ADAMTS13 activity, but lower levels of ADAMTS13 in complex with larger VWF multimers.
Transfusion 04/2013; · 3.22 Impact Factor
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Charles L Bennett,
Sony Jacob,
Brianne L Dunn,
Peter Georgantopoulos,
X Long Zheng,
Hau C Kwaan,
June M McKoy,
Jametta S Magwood,
Zaina P Qureshi,
Nicholas Bandarenko, [......],
Patricia M Carey,
Ravindra Sarode,
Joseph E Kiss,
Constance Danielson,
Thomas L Ortel,
William F Clark,
Richard J Ablin,
Gail Rock, Masanori Matsumoto,
Yoshihiro Fujimura
British Journal of Haematology 03/2013; · 4.94 Impact Factor
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ABSTRACT: Von Willebrand factor (VWF)-cleaving protease (ADAMTS13) cleaves ultralarge VWF secreted from endothelium and by which is regulating its physiologic function. An imbalance between ultralarge VWF secretion and ADAMTS13 level occurs in sepsis and may cause multiple organ dysfunction. We evaluated the association between the VWF-propeptide (VWF-pp) /ADAMTS13 ratio and disease severity in patients with severe sepsis or septic shock. In 27 patients with severe sepsis or septic shock and platelet count < 120 000/μL, we measured plasma VWF, VWF-pp, and ADAMTS13 levels on hospital days 1, 3, 5, and 7. The VWF-pp/ADAMTS13 ratio was increased > 12-fold in patients with severe sepsis or septic shock on day 1 and remained markedly high on days 3, 5, and 7 compared with normal control subjects. The VWF-pp/ADAMTS13 ratio significantly correlated with Acute Physiology and Chronic Health Evaluation II (APACHE II) score on days 1 and 5; Sepsis-related Organ Failure Assessment (SOFA) score on days 1, 3, and 5; maximum SOFA score and tumor necrosis factor α level on days 1, 3, 5, and 7; and creatinine level on days 1, 5, and 7. Patients with > stage 1 acute kidney injury had significantly higher VWF-pp/ADAMTS13 ratio than patients without acute kidney injury. In summary, the VWF-pp/ ADAMTS13 ratio was associated with disease severity in patients with severe sepsis or septic shock and may help identify patients at risk for multiple organ dysfunction by detecting severe imbalance between ultralarge VWF secretion and ADAMTS13 level.
Shock (Augusta, Ga.) 03/2013; · 2.87 Impact Factor
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Masanori Matsumoto
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ABSTRACT: Thrombotic thrombocytopenic purpura (TTP) is a disorder caused by excessive platelet aggregation in multiple organs. Unless the patients are treated with plasma exchange, this disorder leads to early death. Recent studies show that TTP is caused by deficiency of a plasma metalloprotease ADAMTS13, which specifically cleaves von Willebrand factor (VWF). In the absence of ADAMTS13, unusually large VWF multimers (UL-VWFMs) released from endothelial cells are not cleaved appropriately, and cause platelet-rich microvascular thrombosis under high shear stress. Deficiency of ADAMTS13 is caused by autoantibodies against ADAMTS13 in patients with acquired TTP and mutations of the ADAMTS13 gene in congenital TTP. ADAMTS13 antibodies may inhibit enzymatic function or clear ADAMTS13 from circulation. Anti-ADAMTS13 antibodies are comprised predominantly of immunoglobulin class G (IgG). Epitope mapping studies showed that antibodies direct towards the spacer domain of ADAMTS13 are present in most patients with acquired TTP. The Spacer domain contributes to the binding of ADAMTS13 to unfolded VWF. Plasma exchange therapy for acquired TTP is effective because of removing ADAMTS13 autoantibodies and UL-VWFMs, and supply of ADAMTS13. In addition to plasma exchange, corticostroids are usually used for reducing the production of anti-ADAMTS13 antibodies. Recent studies have shown benefit in using rituximab as a first line therapy of acute acquired TTP.
Japanese Journal of Clinical Immunology 01/2013; 36(2):95-103.
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Saori Tanabe,
Hideo Yagi,
Toshiyuki Kimura,
Ayami Isonishi,
Seiji Kato,
Yoko Yoshida,
Masaki Hayakawa, Masanori Matsumoto,
Shinsuke Ohtaki,
Yukihiro Takahashi,
Yoshihiro Fujimura
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ABSTRACT: Upshaw-Schulman syndrome (USS) is caused by a congenital deficit in ADAMTS13 activity owing to genetic mutations. USS is characterized by severe neonatal jaundice with a negative Coombs test and repeated childhood episodes of thrombocytopenia reversible by fresh frozen plasma (FFP) infusions. We present two patients with USS, both of whom underwent exchange blood transfusions as newborns, although the disease subsequently developed along different clinical courses. USS-CC5 initially received a diagnosis of neonatal jaundice due to fetomaternal ABO incompatibility with an indirect positive Coombs test, which masked the diagnosis of USS. Before prophylactic FFP infusions were initiated, USS-CC5 had chronic thrombocytopenia. In contrast, thrombocytopenia developed in USS-HH4 only in response to infections and spontaneously normalized without FFP infusions. Analyses of the ADAMTS13 genes in USS-CC5 and USS-HH4 revealed compound heterozygotes of p.R398C/p.Q723K and p.Q449X/p.Q1374Sfs, respectively. Analysis of von Willebrand factor (VWF) multimers in plasma samples taken from both patients in remission showed single symmetrical multimer bands, which differ from the triplet structure of bands observed in normal samples. These data suggested that plasma VWF multimers in the patients had not been proteolytically modified. Our results indicate the presence of a previously unknown regulatory mechanism for VWF-dependent high-shear stress-induced platelet aggregation.
International journal of hematology 11/2012; · 1.17 Impact Factor
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Sony Jacob,
Brianne L Dunn,
Zaina P Qureshi,
Nicholas Bandarenko,
Hau C Kwaan,
Dilip K Pandey,
June M McKoy,
Sara E Barnato,
Jeffrey L Winters,
John F Cursio, [......],
William F Clark,
Gail Rock, Masanori Matsumoto,
Yoshihiro Fujimura,
X Long Zheng,
Hao Chen,
Fei Chen,
John M Armstrong,
Dennis W Raisch,
Charles L Bennett
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ABSTRACT: Thienopyridine-derivatives (ticlopidine, clopidogrel, and prasugrel) are the primary antiplatelet agents. Thrombotic thrombocytopenic purpura (TTP) is a rare drug-associated syndrome, with the thienopyridines being the most common drugs implicated in this syndrome. We reviewed 20 years of information on clinical, epidemiologic, and laboratory findings for thienopyridine-associated TTP. Four, 11, and 11 cases of thienopyridine-associated TTP were reported in the first year of marketing of ticlopidine (1989), clopidogrel (1998), and prasugrel (2010), respectively. As of 2011, the FDA received reports of 97 ticlopidine-, 197 clopidogrel-, and 14 prasugrel-associated TTP cases. Severe deficiency of ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) was present in 80% and antibodies to 100% of these TTP patients on ticlopidine, 0% of the patients with clopidogrel-associated TTP (p < 0.05), and an unknown percentage of patients with prasugrel-associated TTP. TTP is associated with use of each of the three thienopyridines, although the mechanistic pathways may differ.
Seminars in Thrombosis and Hemostasis 10/2012; · 4.52 Impact Factor
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Atsushi Yamashita,
Kensaku Nishihira,
Yunosuke Matsuura,
Takashi Ito,
Kouichi Kawahara,
Kinta Hatakeyama,
Teruto Hashiguchi,
Ikuro Maruyama,
Hideo Yagi, Masanori Matsumoto,
Yoshihiro Fujimura,
Kazuo Kitamura,
Yoshisato Shibata,
Yujiro Asada
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ABSTRACT: To examine the presence of CD34-positive cells and intranuclear factors in acute coronary thrombi, we compared thrombi in patients with type 2 diabetes mellitus (DM, n = 21) and without DM (n = 29). Immunohistochemical staining revealed the constitutive presence of platelets, fibrin, erythrocytes, neutrophils, extracellular high-mobility group box 1 (HMGB-1), and histone H3 in all thrombi. There were significantly more oval or flat CD34-positive cells and significantly larger HMGB-1-positive areas in the thrombi from patients with DM. The flat CD34-positive cells expressed ecto-nucleoside triphosphate diphosphohydrolase (a platelet aggregation inhibitor). The number of CD34-positive cells was negatively correlated with the serum levels of glucose and hemoglobin A1c, whereas the HMGB-1-positive area was positively correlated with the levels of serum glucose. The paucity of CD34-positive cells and the high levels of HMGB-1 expression in acute coronary thrombi from patients with type 2 DM could facilitate thrombus formation.
Atherosclerosis 07/2012; 224(2):511-4. · 3.79 Impact Factor
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ABSTRACT: Cilostazol is an anti-platelet drug that reversibly inhibits phosphodiesterase III (PDE-III), which is ubiquitously expressed in platelets and various tissues. PDE-III converts cyclic adenosine monophosphate (cAMP) to 5'-AMP and up-regulates the intracellular concentration of cAMP, a potent inhibitor of platelet aggregation. Unlike other anti-platelet drugs, cilostazol is unique because patients receiving this drug do not have a significantly prolonged bleeding time, but the reasons for this difference are still unknown. In this study, we have examined how cilostazol inhibits platelet thrombus formation using anti-coagulated normal whole blood in which the platelets were labeled with a fluorescent dye in comparison with the anti-GPIIb/IIIa agent, tirofiban. We used an in vitro assay to examine mural platelet thrombus growth on a collagen surface under a high-shear rate flow in the absence of ADAMTS13 activity. These experimental conditions mimic the blood flow in patients with thrombotic thrombocytopenic purpura. Using this model, we clearly determined that cilostazol down-regulates the height of mural platelet thrombi formed on a collagen surface in a dose-dependent manner, without affecting the surface coverage. The concentration of cilostazol used in this study was relatively high (60-120 μM) compared to clinically relevant concentrations (1-3 μM), which may be due to the in vivo synergistic effects of PDE-III present in other tissues aside from platelets. Cilostazol does not affect the initial formation of platelet thrombi, but does inhibit the height of thrombi. These results showed a sharp contrast to tirofiban, and address why cilostazol does not significantly prolong bleeding time, despite its strong anti-platelet activity.
European journal of pharmacology 07/2012; 691(1-3):151-5. · 2.59 Impact Factor
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ABSTRACT: von Willebrand factor (VWF) cleavage by ADAMTS13 is mediated by multi-step interactions between their multi-domain structures. To clarify the relationship between inhibitory effects of monoclonal antibodies and epitopes on each ADAMTS13 domain, we analyzed how each ADAMTS13 domain contributes to catalyze VWF using a mouse anti-ADAMTS13 monoclonal antibody panel.
FRETS-VWF73 assay was used to examine the effects of 14 anti-ADAMTS13 monoclonal antibodies on the catalytic activity of plasma ADAMTS13. Epitope mapping was performed using phage surface display. Libraries expressing peptide fragments of ADAMTS13 were screened with the monoclonal antibodies.
Eleven epitopes of 14 monoclonal antibodies were successfully defined. Three monoclonal antibodies recognizing metalloprotease or disintegrin-like domains strongly inhibited the catalytic activity and their epitopes were on Gln159-Asp166, Tyr 305-Glu327, and Asn308-Glu376. Five monoclonal antibodies recognizing TSP1-3 to -7 repeats showed weak inhibitory effects, and their epitopes were on Pro744-Ala806, Pro856-Cys864, Gln892-Gly940, Cys1007-Cys1072, and Gln1163-Asn1185. Four monoclonal antibodies recognizing the TSP1-1, TSP1-2, CUB1 or CUB2 domains had no inhibitory effects, and their epitopes, except that for TSP1-1, were Pro682-Cys742, Thr1200-Cys1213, and Gln1409-Glu1414. Two monoclonal antibodies recognizing cysteine-rich and spacer domains showed moderate inhibitory effects, but their epitopes were not determined.
We revealed the epitopes of 11 monoclonal anti-ADAMTS13 antibodies on each of the domains and clarified their association with inhibitory effects on VWF catalysis under static conditions. Catalytic activity correlated strongly with the epitopes on metalloprotease and disintegrin-like domains, weakly with those on TSP1-3 to -7 repeats, and negatively with those on TSP1-1, -2, and CUB domains.
Thrombosis Research 06/2012; 130(3):e79-83. · 2.44 Impact Factor
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Yukiyo Yamamoto-Suzuki,
Yoshihiko Sakurai,
Yoshihiro Fujimura, Masanori Matsumoto,
Jiharu Hamako,
Tetsuro Kokubo,
Hitoshi Kitagawa,
Sarkar M A Kawsar,
Yuki Fujii,
Yasuhiro Ozeki,
Fumio Matsushita,
Taei Matsui
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ABSTRACT: Botrocetin is a heterodimer snake venom protein that induces von Willebrand factor (VWF)- and platelet glycoprotein Ib (GPIb)-dependent platelet agglutination in vitro. We have cloned cDNAs for a botrocetin-2 from a cDNA library of the venom gland of Bothrops jararaca having a high similarity with botrocetin subunits. Recombinant botrocetin-2, expressed in 293T cells, showed cofactor activity comparable to natural botrocetin. In a single subunit expression experiment, a dimer of the β subunit was obtained, and it showed reduced, but apparent, platelet agglutination activity. Ala scanning mutagenesis showed that substitutions at Asp62, Asp70, Arg115, or Lys117 in the β subunit reduced platelet agglutination activity. The 3D homology modeling of botrocetin-2 complexed with the VWF A1 domain and GPIbα indicated that Asp62, Arg115, and Lys117 of the β subunit are located near Arg218 and Asp222 of GPIbα, respectively, and that Aspβ70 is in proximity to Gln1391 of the A1 domain. Our results indicate that these charged amino acid residues in the β subunit have a preferential role in the activity of botrocetin-2. Since it has been time-consuming and difficult to obtain homogeneous botrocetin from natural venom, recombinant botrocetin-2 has potential benefits for clinical and basic investigations into hemostasis and thrombosis as a standard reagent.
Biochemistry 05/2012; 51(26):5329-38. · 3.42 Impact Factor
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ABSTRACT: A 41-year-old Japanese man complained of a left-sided visual disturbance. Imaging by magnetic resonance angiography revealed A 41-year-old Japanese man complained of a left-sided visual disturbance. Imaging by magnetic resonance angiography revealed
a narrowing of the left internal cervical artery. Thus, ticlopidine (Tc) administration was started at a daily dose of 300 a narrowing of the left internal cervical artery. Thus, ticlopidine (Tc) administration was started at a daily dose of 300
mg. However, 2 weeks later, severe thrombocytopenia, fever, nausea, and psychiatric symptoms developed; Tc was therefore discontinued. mg. However, 2 weeks later, severe thrombocytopenia, fever, nausea, and psychiatric symptoms developed; Tc was therefore discontinued.
Based on the diagnostic hallmark of 5 clinical signs, the patient’s disease was diagnosed as thrombotic thrombocytopenic purpura Based on the diagnostic hallmark of 5 clinical signs, the patient’s disease was diagnosed as thrombotic thrombocytopenic purpura
(TTP). Daily plasmapheresis was performed for the first 4 days, and the patient’s clinical signs gradually improved. Von Willebrand (TTP). Daily plasmapheresis was performed for the first 4 days, and the patient’s clinical signs gradually improved. Von Willebrand
factor-cleaving protease (vWF-CPase) activity in his plasma was less than 3% of that of the control sample at diagnosis, butthe control sample at diagnosis, but
that value recovered steadily following plasmapheresis. In addition, immunoglobulin G purified from the patient plasma inhibited that value recovered steadily following plasmapheresis. In addition, immunoglobulin G purified from the patient plasma inhibited
vWF-CPase activity in normal plasma with a specific activity of 0.8 Bethesda units/mg. No sign of TTP relapse has been noted vWF-CPase activity in normal plasma with a specific activity of 0.8 Bethesda units/mg. No sign of TTP relapse has been noted
following cessation of Tc. Thus, it was concluded that the patient developed TTP by producing an inhibitory autoantibody against following cessation of Tc. Thus, it was concluded that the patient developed TTP by producing an inhibitory autoantibody against
vWF-CPase activity that was presumably triggered by Tc administration. vWF-CPase activity that was presumably triggered by Tc administration.
International Journal of Hematology 04/2012; 74(3):347-351. · 1.27 Impact Factor
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ABSTRACT: Thrombotic thrombocytopenic purpura (TTP) is a life-threatening generalized disease with pathological conditions termed thrombotic microangiopathy (TMA). TTP is thought to predominantly affect adults and to rarely occur in children. Currently, TTP is defined by a severe deficiency in the activity of ADAMTS13, a metalloprotease that specifically cleaves unusually large von Willebrand factor multimers under high shear stress. Genetic mutations in and acquired autoantibodies to ADAMTS13 cause congenital TTP (termed Upshaw-Schulman syndrome [USS]) and acquired TTP, respectively. Because of very few overt clinical signs for TTP, USS is often misdiagnosed as chronic idiopathic thrombocytopenic purpura or overlooked during childhood. However, in women with USS, pregnancy can induce thrombocytopenia followed by the development of TTP. Furthermore, early childhood cases of acquired idiopathic TTP have not been characterized. From 1998 to 2008, our institution at Nara Medical University functioned as a TMA referral center in Japan and collected a large dataset on 919 TMA patients (Intern Med 2010;49:7-15). This registry contains 324 patients with a severe deficiency in ADAMTS13 activity, including 41 patients with USS and 283 patients with acquired TTP. Of note, the latter population contains 17 patients who were enrolled as children (≤ 15years old), including 14 children with idiopathic TTP and three with connective tissue disease-associated TTP. Of the 14 patients with idiopathic TTP, five were very young children (under 2 years old). This study focused on these 58 patients (41 USS and 17 acquired TTP) who were diagnosed with a severe deficiency in ADAMTS13 activity during childhood, causing a paradigm shift in our concept of TTP.
La Presse Médicale 03/2012; 41(3 Pt 2):e137-55. · 0.67 Impact Factor
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Hiroaki Takaya,
Masahito Uemura,
Yoshihiro Fujimura, Masanori Matsumoto,
Tomomi Matsuyama,
Seiji Kato,
Chie Morioka,
Hiromichi Ishizashi,
Yuji Hori,
Masao Fujimoto,
Tatsuhiro Tsujimoto,
Hideto Kawaratani,
Masahisa Toyohara,
Norio Kurumatani,
Hiroshi Fukui
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ABSTRACT: Aim: Decreased plasma ADAMTS13 activity (ADAMTS13:AC) results in accumulation of unusually large von Willebrand factor multimers and platelet thrombi formation. Our aim was to evaluate whether ADAMTS13:AC is a prognostic marker in patients with liver cirrhosis. Methods: Plasma ADAMTS13:AC and its related parameters were examined in 108 cirrhotic patients. Results: ADAMTS13:AC decreased as the severity of liver disease increased (means: controls 100%, Child A-cirrhotics 79%, Child B-cirrhotics 63%, and Child C-cirrhotics 31%). ADAMTS13:AC markedly decreased in the cirrhotics with hepatorenal syndrome, refractory ascites and hepatic encephalopathy. The cumulative survival time was the shortest (median: 4.5 months) in the cirrhotics with severe to moderate ADAMTS13:AC deficiency (<3-25%), followed by those with mild ADAMTS13:AC deficiency (25-50%), and was the longest in those with normal activity (>50%). In contrast, based on the Child-Turcotte-Pugh (CTP) score, Child C-cirrhotics had the worst survival, but the survival probabilities did not differ between Child A and B cirrhotics. Based on the Model for End-Stage Liver Disease (MELD) score, the survival was the worst for the cirrhotics in the fourth quartile, but it was not different among cirrhotics in the first three quartiles. Cox proportional-hazards regression analysis showed that ADAMTS13:AC and serum albumin were independent factors affecting the survival. Conclusions: ADAMTS13:AC concomitantly decreases as the functional liver capacity decreases. This activity may be a useful prognostic marker that is equal or superior to the CTP score and the MELD score to predict not only the short-term prognosis but also the long-term survival of the cirrhotic patients.
Hepatology Research 01/2012; 42(5):459-72. · 2.20 Impact Factor
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01/2012; , ISBN: 978-953-307-985-1
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ABSTRACT: Thrombotic thrombocytopenic purpura (TTP) is a type of thrombotic microangiopathy (TMA). Studies report that the majority of TTP patients present with a deficiency of ADAMTS13 activity. In a database of TMA patients in Japan identified between 1998 and 2008, 186 patients with first onset of acquired idiopathic (ai) ADAMTS13-deficient TTP (ADAMTS13 activity <5%) were diagnosed. The median age of onset of TTP in this group of patients was 54 years, 54.8% were female, 75.8% had renal involvement, 79.0% had neurologic symptoms, and 97.8% had detectable inhibitors to ADAMTS13 activity. Younger patients were less likely to present with renal or neurologic dysfunction (p<0.01), while older patients were more likely to die during the TTP hospitalization (p<0.05). Findings from this cohort in Japan differ from those reported previously from the United States, Europe, and Korea with respect to age at onset (two decades younger in the other cohort) and gender composition (60% to 100% female in the other cohort). We conclude that in one of the largest cohorts of ai-TTP with severe deficiency of ADAMTS13 activity reported to date, demographic characteristics differ in Japanese patients relative to those reported from a large Caucasian registry from Western societies. Additional studies exploring these findings are needed.
PLoS ONE 01/2012; 7(3):e33029. · 4.09 Impact Factor
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Nihon Naika Gakkai Zasshi 05/2011; 100(5):1296-307.
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ABSTRACT: Autoantibodies to ADAMTS13 have a pivotal role in the pathogenesis of acquired thrombotic thrombocytopenic purpura (TTP). By decreasing the function of ADAMTS13, autoantibodies impair the cleavage of ultra-large von Willebrand factor (UL-VWF) multimers into smaller sizes, leading to lethal platelet-VWF thrombi in the microcirculation. We therefore aimed to determine the sites of autoantibody recognition on ADAMTS13.
In this study, IgG purified from 13 acquired TTP patients were examined to determine their binding sites on ADAMTS13. Immobilized IgG on microtiter plate or proteinG beads was screened by phage library expressing various peptides of ADAMTS13.
In screening, diverse peptide sequences were obtained from almost all of the ADAMTS13 domains, including the spacer domain, which is considered a major binding site. In particular, we detected an identical amino-acid sequence in the C-terminus of the spacer domain from Gly662 to Val687 that was recognized by autoantibodies from 5 TTP patients. The specific autoantibody was expected to be associated with the plasma levels of the ADAMTS13 antigen or activity, and with the quantity of ADAMTS13 autoantibodies or the inhibitory autoantibody titer in TTP patient plasma. These measurements, however, did not seem to be related to the presence or absence of the specific autoantibody.
These findings indicate that the specific autoantibody might be a feature of acquired TTP, although its clinical significance remains to be elucidated.
Thrombosis Research 04/2011; 128(2):169-73. · 2.44 Impact Factor
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ABSTRACT: We describe an 18-year-old woman infected with H1N1 influenza followed by thrombotic microangiopathy. During the acute phase, her plasma levels of von Willebrand factor (VWF) were remarkably elevated, whereas those of ADAMTS13 were reduced without its inhibitors, generating a markedly high ratio of VWF to ADAMTS13 in circulation. A retrospective analysis established the following hypothesis: an influenza-mediated cytokine storm induced an enhanced release of unusually large VWF multimers (UL-VWFM) from vascular endothelial cells, generating platelet thrombi in microcirculatures under high shear stress. Plasma exchange removed UL-VWFM and cytokines, and rescued her life. This report sheds a light on a hitherto unrecognized influenza complication.
Internal Medicine 01/2011; 50(6):643-7. · 0.94 Impact Factor
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ABSTRACT: The liver plays a central role in hemostasis by synthesizing clotting factors, coagulation inhibitors, and fibrinolytic proteins. Liver cirrhosis (LC), therefore, impacts on both primary and secondary hemostatic mechanisms. ADAMTS13 is a metalloproteinase, produced exclusively in hepatic stellate cells, and specifically cleaves unusually large von Willebrand factor multimers (UL-VWFM). Deficiency of ADAMTS13 results in accumulation of UL-VWFM, which induces platelet clumping or thrombi under high shear stress, followed by sinusoidal microcirculatory disturbances and subsequent progression of liver injuries, eventually leading to multiorgan failure. The marked imbalance between decreased ADAMTS13 activity (ADAMTS13 : AC) and increased production of UL-VWFM indicating a high-risk state of platelet microthrombi formation was closely related to functional liver capacity, hepatic encephalopathy, hepatorenal syndrome, and intractable ascites in advanced LC. Some end-stage LC patients with extremely low ADAMTS13 : AC and its IgG inhibitor may reflect conditions similar to thrombotic thrombocytopenic purpura (TTP) or may reflect "subclinical TTP." Hence, cirrhotic patients with severe to moderate deficiency of ADAMTS13 : AC may be candidates for FFP infusion as a source of ADAMTS13 or for recombinant ADAMTS13 supplementation. Such treatments may improve the survival of patients with decompensated LC.
International journal of hepatology. 01/2011; 2011:759047.
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ABSTRACT: ADAMTS13 is a metalloproteinase that specifically cleaves unusually large von Willbrand factor multimers under high-shear stress. Deficiency of ADAMTS13 activity induces a life-threatening generalized disease, thrombotic thrombocytopenic purpura. We established a simple and efficient method to purify plasma ADAMTS13 (pADAMTS13) from cryosupernatant using an anti-ADAMTS13 monoclonal antibody (A10) that recognizes a conformational epitope within the disintegrin-like domain. Using the purified pADAMTS13, the amino acid residues involved in cleavage by thrombin, plasmin and leucocyte elastase were determined, and the carbohydrate moieties of this enzyme was analysed by lectin blots. Purified pADAMTS13 had a specific activity of 300 U/mg (25,057-fold purification) and the pI was 5.1-5.5. Cleavage sites of the purified pADAMTS13 by three proteases were identified; thrombin cleaved the four peptidyl bonds between Arg257-Ala258, Arg459-Ser460, Arg888-Thr889 and Arg1176-Arg1177, plasmin cleaved the three peptidyl bonds between Arg257-Ala258, Arg888-Thr889 and Arg1176-Arg1177, and elastase cleaved the two peptidyl bonds between Ile380-Ala381 and Thr874-Ser875. Lectin blot analysis indicated the presence of non-reducing terminal α2-6 and α2-3-linked sialic acid residues with penultimate β-galactose residues on the N- and O-linked sugar chains of pADAMTS13, suggesting that pADAMTS13 is cleared from the circulation via the hepatic asialoglycoprotein receptor like other plasma glycoproteins.
Journal of biochemistry 10/2010; 148(4):403-11. · 1.95 Impact Factor
