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Long X Zheng - One of the best experts on this subject based on the ideXlab platform.
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transfusion of platelets loaded with recombinant ADAMTS13 a disintegrin and metalloprotease with thrombospondin type 1 repeats 13 is efficacious for inhibiting arterial thrombosis associated with thrombotic thrombocytopenic purpura
Arteriosclerosis Thrombosis and Vascular Biology, 2018Co-Authors: Mohammad S Abdelgawwad, Wenjing Cao, Liang Zheng, Nicole K Kocher, Lance A Williams, Long X ZhengAbstract:Objective- ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats-13) cleaves VWF (von Willebrand factor). This process is essential for hemostasis. Severe deficiency of plasma ADAMTS13 activity, most commonly resulting from autoantibodies against ADAMTS13, causes thrombotic thrombocytopenic purpura. Therapeutic plasma exchange is the standard of care to date, which removes autoantibodies and replenishes ADAMTS13. However, such a therapy is often ineffective to raise plasma ADAMTS13 activity, and in-hospital mortality rate remains as high as 20%. Approach and Results- To overcome the inhibition by autoantibodies, we developed a novel approach by delivering rADAMTS13 (recombinant ADAMTS13 ) using platelets as vehicles. We show that both human and murine platelets can uptake rADAMTS13 ex vivo. The endocytosed rADAMTS13 within platelets remains intact, active, and is stored in α-granules. Under arterial shear (100 dyne/cm2), the rADAMTS13 in platelets is released and effectively inhibits platelet adhesion and aggregation on a collagen-coated surface in a concentration-dependent manner. Transfusion of rADAMTS13-loaded platelets into ADAMTS13-/- mice dramatically reduces the rate of thrombus formation in the mesenteric arterioles after FeCl3 injury. An ex vivo transfusion of rADAMTS13-loaded platelets to a reconstituted whole blood containing plasma from a patient with immune-mediated thrombotic thrombocytopenic purpura and the cellular components (eg, erythrocytes and leukocytes) from a healthy individual, as well as a fresh whole blood obtained from a patient with congenital or immune-mediated thrombotic thrombocytopenic purpura also dramatically reduces the rate of thrombus formation under arterial flow. Conclusions- Our results demonstrate that transfusion of rADAMTS13-loaded platelets may be a novel and potentially effective therapeutic approach for arterial thrombosis, associated with congenital and immune-mediated thrombotic thrombocytopenic purpura.
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ADAMTS13 test and or plasmic clinical score in management of acquired thrombotic thrombocytopenic purpura a cost effective analysis
Transfusion, 2017Co-Authors: Chong H Kim, Long X Zheng, Lance A Williams, Sierra C Simmons, Elizabeth M Staley, Huy P PhamAbstract:BACKGROUND The ADAMTS13 test distinguishes thrombotic thrombocytopenic purpura (TTP) from other thrombotic microangiopathies (TMAs). The PLASMIC score helps determine the pretest probability of ADAMTS13 deficiency. Due to inherent limitations of both tests, and potential adverse effects and cost of unnecessary treatments, we performed a cost-effectiveness analysis (CEA) investigating the benefits of incorporating an in-hospital ADAMTS13 test and/or PLASMIC score into our clinical practice. STUDY DESIGN AND METHODS A CEA model was created to compare four scenarios for patients with TMAs, utilizing either an in-house or a send-out ADAMTS13 assay with or without prior risk stratification using PLASMIC scoring. Model variables, including probabilities and costs, were gathered from the medical literature, except for the ADAMTS13 send-out and in-house tests, which were obtained from our institutional data. RESULTS If only the cost is considered, in-house ADAMTS13 test for patients with intermediate- to high-risk PLASMIC score is the least expensive option ($4,732/patient). If effectiveness is assessed as measured by the number of averted deaths, send-out ADAMTS13 test is the most effective. Considering the cost/effectiveness ratio, the in-house ADAMTS13 test in patients with intermediate- to high-risk PLASMIC score is the best option, followed by the in-house ADAMTS13 test without the PLASMIC score. CONCLUSIONS In patients with clinical presentations of TMAs, having an in-hospital ADAMTS13 test to promptly establish the diagnosis of TTP appears to be cost-effective. Utilizing the PLASMIC score further increases the cost-effectiveness of the in-house ADAMTS13 test. Our findings indicate the benefit of having a rapid and reliable in-house ADAMTS13 test, especially in the tertiary medical center.
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expression of ADAMTS13 in normal and abnormal placentae and its potential role in angiogenesis and placenta development
Arteriosclerosis Thrombosis and Vascular Biology, 2017Co-Authors: Juan Xiao, Long X Zheng, Yun Feng, Lei Fan, Jing Liu, Xue Zeng, Kaiyue Chen, Xi Chen, Xiaoshui Zhou, Suhua ChenAbstract:Objective— ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 repeats, member 13) is primarily synthesized in liver. The biosynthesis and its physiological role in placenta are not known. Approach and Results— We used real-time polymerase chain reaction, immunohistochemistry, and Western blotting analyses, as well as proteolytic cleavage of FRETS-VWF73, to determine ADAMTS13 expression in placenta and trophoblasts obtained from individuals with normal pregnancy and patients with severe preeclampsia. We also determined the role of ADAMTS13 in extravillous trophoblasts using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, wound scratch assay, transwell migration assay, tube formation assay, and tissue outgrowth assays. We demonstrated that full-length and proteolytically active ADAMTS13 was expressed in normal human placenta, primarily in the trophoblasts and villous core fetal vessel endothelium during pregnancy. Placental expression of ADAMTS13 mRNA, protein, and proteolytic activity was at the highest levels during the first trimester and significantly reduced at the term of gestation. Additionally, significantly reduced levels of placental ADAMTS13 expression was detected under hypoxic conditions and in patients with preeclampsia. In addition, recombinant ADAMTS13 protease stimulated proliferation, migration, invasion, and network formation of trophoblastic cells in culture. Finally, knockdown of ADAMTS13 expression attenuated the ability of tube formation in HTR-8/SVNEO cells and the extravillous trophoblast outgrowth in placental explants. Conclusions— Our results demonstrate for the first time the expression of ADAMTS13 mRNA and protein in normal and abnormal placental tissues and its role in promoting angiogenesis and trophoblastic cell development. The findings support the potential role of the ADAMTS13–von Willebrand factor pathway in normal pregnancy and pathogenesis of preeclampsia.
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Description ADAMTS13 (A Disintegrin And Metalloprotease with ThromboSpondin Type 1 repeats,
2016Co-Authors: Long X ZhengAbstract:13), a plasma metalloprotease, cleaves von Willebrand factor (VWF) [1,2]. This cleavage is crucial for reducing the size of VWF multimers and adhesiveness, thereby preventing excessive platelet aggregation and thrombus formation at sites of vascular injury [3,4]. Deficiency of plasma ADAMTS13 activity could result in an accumulation of newly released ultra large (UL) VWF on endothelial cells where it is synthesized [5] and in blood [6], leading to a potentially fatal syndrome, thrombotic thrombocytopenic purpura (TTP). TTP is clinically characterized by profound thrombocytopenia and microangiopathic hemolytic anemia (low hematocrit, elevated serum lactate dehydrogenase, and fragmentation of red blood cells) [7]. Some patients may present signs and symptom of neurologic and/or renal abnormalities [7]. There are two major types of TTP: Hereditary and acquired. Hereditary TTP is caused by inherited mutations of ADAMTS13 gene, which result in severe deficiency (<5%) of plasma ADAMTS13 activity [1]. Acquired TTP, on the other hand, is primarily caused by acquired immunoglobulin G (IgG) autoantibodies against ADAMTS1 [8,9]. The autoantibodies bind the exosites that are critical for substrate recognition, thereby inhibiting the cleavage of VWF by ADAMTS13. Recent studies have shown that the space
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genetic ablation of ADAMTS13 gene dramatically accelerates the formation of early atherosclerosis in a murine model
Arteriosclerosis Thrombosis and Vascular Biology, 2012Co-Authors: Shengyu Jin, Junichiro Tohyama, Robert C Bauer, Na Nora Cao, Daniel J Rader, Long X ZhengAbstract:Objective— ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats-13) cleaves von Willebrand factor, thereby modulating thrombosis and inflammation. Low plasma ADAMTS13 activity is associated with cardiovascular events, including myocardial and cerebral infarction. Here, we investigated the role of ADAMTS13 in the development of early atherosclerosis in a murine model. Methods and Results— Apolipoprotein E–null (ApoE −/− ) and ADAMTS13-null (ADAMTS13 −/− ) ApoE −/− mice were fed with a high-fat Western diet for 12 weeks. Atherosclerotic lesions in the aorta and aortic roots were quantified after staining. Leukocyte rolling and adhesion onto cremaster venules after oxidative injury were determined by intravital microscopy. Although plasma cholesterol levels were largely similar in both groups, the extent of atherosclerotic lesions in the aorta en face and in the aortic roots in the ADAMTS13 −/− ApoE −/− mice increased ≈5.5-fold ( P =0.0017) and ≈6.1-fold ( P =0.0037), respectively. In addition, the ratio of plasma high- to low-molecular-weight von Willebrand factor multimers increased ≈3-fold. The leukocyte rolling velocities were significantly reduced ( P P =0.0026) and macrophage infiltration into the atherosclerotic lesions in the ADAMTS13 −/− ApoE −/− mice. Conclusion— Our results suggest that ADAMTS13 plays a critical role in modulating the development of early atherosclerosis, likely through the proteolytic cleavage of ultra-large von Willebrand factor multimers, thereby inhibiting platelet deposition and inflammation.
Roose Elien - One of the best experts on this subject based on the ideXlab platform.
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Immunogenic hotspots in the spacer domain of ADAMTS13 in immune‐mediated thrombotic thrombocytopenic purpura
'Wiley', 2021Co-Authors: Velásquez Pereira, Leydi Carolina, Roose Elien, Graça Nuno, Sinkovits György, Kangro Kadri, Joly Bérangère, Tellier Edwige, Kaplanski Gilles, Falter Tanja, Von Auer CharisAbstract:International audienceBackground Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is caused by anti-ADAMTS13 autoantibodies inducing a severe deficiency of ADAMTS13. Epitope mapping studies on samples obtained during acute iTTP episodes have shown that the iTTP immune response is polyclonal, with almost all patients having autoantibodies targeting the spacer domain of ADAMTS13.Objectives To identify the immunogenic hotspots in the spacer domain of ADAMTS13.Patients/methods A library of 11 full-length ADAMTS13 spacer hybrids was created in which amino acid regions of the spacer domain of ADAMTS13 were exchanged by the corresponding region of the spacer domain of ADAMTS1. Next, the full-length ADAMTS13 spacer hybrids were used in enzyme-linked immunosorbent assay to epitope map anti-spacer autoantibodies in 138 samples from acute and remission iTTP patients.Results Sixteen different anti-spacer autoantibody profiles were identified with a similar distribution in acute and remission patients. There was no association between the anti-spacer autoantibody profiles and disease severity. Almost all iTTP samples contained anti-spacer autoantibodies against the following three regions: amino acid residues 588-592, 602-610, and 657-666 (hybrids E, G, and M). Between 31% and 57% of the samples had anti-spacer autoantibodies against amino acid regions 572-579, 629-638, 667-676 (hybrids C, J, and N). In contrast, none of the samples had anti-spacer autoantibodies against amino acid regions 556-563, 564-571, 649-656, and 677-685 (hybrids A, B, L, and O).Conclusion We identified three hotspot regions (amino acid regions 588-592, 602-610, and 657-666) in the spacer domain of ADAMTS13 that are targeted by anti-spacer autoantibodies found in a large cohort of iTTP patients
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Antibodies that conformationally activate ADAMTS13 allosterically enhance metalloprotease domain function
'American Society of Hematology', 2020Co-Authors: Schelpe An-sofie, James T B Crawley, Roose Elien, Petri Anastasis, Pareyn Inge, Deckmyn Hans, De Meyer, Simon F, Vanhoorelbeke KarenAbstract:Plasma ADAMTS13 circulates in a folded conformation that is stabilized by an interaction between the central Spacer domain and the C-terminal CUB (complement components C1r and C1s, sea urchin protein Uegf, and bone morphogenetic protein-1) domains. Binding of ADAMTS13 to the VWF D4(-CK) domains or to certain activating murine monoclonal antibodies (mAbs) induces a structural change that extends ADAMTS13 into an open conformation that enhances its function. The objective was to characterize the mechanism by which conformational activation enhances ADAMTS13-mediated proteolysis of VWF. The activating effects of a novel anti-Spacer (3E4) and the anti-CUB1 (17G2) mAbs on the kinetics of proteolysis of VWF A2 domain fragments by ADAMTS13 were analyzed. mAb-induced conformational changes in ADAMTS13 were investigated by enzyme-linked immunosorbent assay. Both mAbs enhanced ADAMTS13 catalytic efficiency (kcat/Km) by ∼twofold (3E4: 2.0-fold; 17G2: 1.8-fold). Contrary to previous hypotheses, ADAMTS13 activation was not mediated through exposure of the Spacer or cysteine-rich domain exosites. Kinetic analyses revealed that mAb-induced conformational extension of ADAMTS13 enhances the proteolytic function of the metalloprotease domain (kcat), rather than augmenting substrate binding (Km). A conformational effect on the metalloprotease domain was further corroborated by the finding that incubation of ADAMTS13 with either mAb exposed a cryptic epitope in the metalloprotease domain that is normally concealed when ADAMTS13 is in a closed conformation. We show for the first time that the primary mechanism of mAb-induced conformational activation of ADAMTS13 is not a consequence of functional exosite exposure. Rather, our data are consistent with an allosteric activation mechanism on the metalloprotease domain that augments active site function.status: publishe
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Open ADAMTS13, induced by antibodies, is a biomarker for subclinical immune-mediated thrombotic thrombocytopenic purpura
'American Society of Hematology', 2020Co-Authors: Roose Elien, Sinkovits György, Tellier Edwige, Kaplanski Gilles, Dekimpe Charlotte, Tellier An-sofie, Joly, Berangere S, Le Besnerais Maelle, Mancini Ilaria, Falter TanjaAbstract:Recently, we showed that ADAMTS13 circulates in an open conformation during the acute phase of immune-mediated thrombotic thrombocytopenic purpura (iTTP). Although the cause of this conformational change remains elusive, ADAMTS13 is primarily closed in iTTP patients in remission with ADAMTS13 activity >50% and undetectable anti-ADAMTS13 autoantibodies, as well as after rituximab treatment, suggesting a role for anti-ADAMTS13 autoantibodies. Therefore, immunoglobulin G from 18 acute iTTP patients was purified and added to closed ADAMTS13 in healthy donor plasma. This resulted in open ADAMTS13 in 14 of 18 (78%) samples, proving that anti-ADAMTS13 autoantibodies can induce an open ADAMTS13 conformation. To further elucidate the conformation of ADAMTS13 in iTTP patients, we studied a novel iTTP patient cohort (n = 197) that also included plasma samples from iTTP patients in remission in whom ADAMTS13 activity was 50%, although free anti-ADAMTS13 autoantibodies were not always detected. Thus, open ADAMTS13 is a hallmark of acute iTTP, as well as a novel biomarker that can be used to detect subclinical iTTP in patients in remission. Finally, a long-term follow-up study in 1 iTTP patient showed that the open conformation precedes a substantial drop in ADAMTS13 activity. In conclusion, we have shown that anti-ADAMTS13 autoantibodies from iTTP patients induce an open ADAMTS13 conformation. Most importantly, an open ADAMTS13 conformation is a biomarker for subclinical iTTP and could become an important tool in TTP management.status: publishe
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Generation and validation of small ADAMTS13 fragments for epitope mapping of anti-ADAMTS13 autoantibodies in immune-mediated thrombotic thrombocytopenic purpura
'Wiley', 2020Co-Authors: Kangro Kadri, Roose Elien, Tellier Edwige, Kaplanski Gilles, Schelpe An-sofie, De Meyer, Simon F, Männik Andres, Voorberg Jan, Vanhoorelbeke KarenAbstract:Background: In immune-mediated thrombotic thrombocytopenic purpura (iTTP), patients develop an immune response against the multidomain enzyme ADAMTS13. ADAMTS13 consists of a metalloprotease (M) and disintegrin-like (D) domain, 8 thrombospondin type 1 repeats (T1-T8), a cysteine-rich (C), a spacer (S), and 2 CUB domains (CUB1-2). Previous epitope mapping studies have used relatively large overlapping ADAMTS13 fragments. Objectives: We aimed at developing small nonoverlapping ADAMTS13 fragments to fine map anti-ADAMTS13 autoantibodies in iTTP patients. Methods: A library of 16 ADAMTS13 fragments, comprising several small (M, DT, C, S, T2-T5, T6-T8, CUB1, CUB2), and some larger fragments with overlapping domains (MDT, MDTC, DTC, CS, T2-T8, CUB1-2, MDTCS, T2-C2), were generated. All fragments, and ADAMTS13, were expressed as a fusion protein with albumin domain 1, and purified. The folding of the fragments was tested using 17 anti-ADAMTS13 monoclonal antibodies with known epitopes. An epitope mapping assay using small ADAMTS13 fragments was set up, and validated by analyzing 18 iTTP patient samples. Results: Validation with the monoclonal antibodies demonstrated that single S and CUB1 were not correctly folded, and therefore CS and CUB1-2 fragments were selected instead of single C, S, CUB1, and CUB2 fragments. Epitope mapping of antibodies of patients with iTTP confirmed that 6 nonoverlapping ADAMTS13 fragments M, DT, CS, T2-T5, T6-T8, and CUB1-2 were sufficient to accurately determine the antibody-binding sites. Conclusion: We have developed a tool to profile patients with iTTP according to their anti-ADAMTS13 antibodies for a better insight in their immune response.status: publishe
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Generation and validation of small ADAMTS13 fragments for epitope mapping of anti‐ADAMTS13 autoantibodies in immune‐mediated thrombotic thrombocytopenic purpura
'Wiley', 2020Co-Authors: Kangro Kadri, Roose Elien, Tellier Edwige, Kaplanski Gilles, De Meyer Simon, Männik Andres, Voorberg Jan, Schelpe An‐sofie, Vanhoorelbeke KarenAbstract:International audienceBackground In immune-mediated thrombotic thrombocytopenic purpura (iTTP), patients develop an immune response against the multidomain enzyme ADAMTS13. ADAMTS13 consists of a metalloprotease (M) and disintegrin-like (D) domain, 8 thrombospondin type 1 repeats (T1-T8), a cysteine-rich (C), a spacer (S), and 2 CUB domains (CUB1-2). Previous epitope mapping studies have used relatively large overlapping ADAMTS13 fragments. Objectives We aimed at developing small nonoverlapping ADAMTS13 fragments to fine map anti-ADAMTS13 autoantibodies in iTTP patients. Methods A library of 16 ADAMTS13 fragments, comprising several small (M, DT, C, S, T2-T5, T6-T8, CUB1, CUB2), and some larger fragments with overlapping domains (MDT, MDTC, DTC, CS, T2-T8, CUB1-2, MDTCS, T2-C2), were generated. All fragments, and ADAMTS13, were expressed as a fusion protein with albumin domain 1, and purified. The folding of the fragments was tested using 17 anti-ADAMTS13 monoclonal antibodies with known epitopes. An epitope mapping assay using small ADAMTS13 fragments was set up, and validated by analyzing 18 iTTP patient samples. Results Validation with the monoclonal antibodies demonstrated that single S and CUB1 were not correctly folded, and therefore CS and CUB1-2 fragments were selected instead of single C, S, CUB1, and CUB2 fragments. Epitope mapping of antibodies of patients with iTTP confirmed that 6 nonoverlapping ADAMTS13 fragments M, DT, CS, T2-T5, T6-T8, and CUB1-2 were sufficient to accurately determine the antibody-binding sites. Conclusion We have developed a tool to profile patients with iTTP according to their anti-ADAMTS13 antibodies for a better insight in their immune response
Hau C Kwaan - One of the best experts on this subject based on the ideXlab platform.
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deficient ADAMTS13 activity in ticlopidine associated thrombotic thrombocytopenic purpura ttp in populations from japan in 2012 validation of findings initially reported in the united states in 1998 and 2000
Blood, 2012Co-Authors: Charles L. Bennett, Hau C Kwaan, Masanori Matsumoto, Peter Georgantopoulos, Sony Jacob, Brianne L Dunn, Zaina P Qureshi, Nicholas Bandarenko, Jeffrey L Winters, Ravindra SarodeAbstract:Abstract 2203 Background: Thrombotic thrombocytopenic purpura (TTP) is frequently characterized by severe ADAMTS13 deficiency, the cause of which is unknown. An important exception is ticlopidine-associated TTP (tc-TTP), the most common drug-induced TTP syndrome. In 1998, a possible association of TTP with ticlopidine was reported. In 1999, two additional series reported this association. In 2000, a fourth study reported severe A DAMTS13 deficiency among six of seven tc-TTP persons- suggesting a causal pathway. All of these reports were from the United States. Recently, we reported characteristics of 186 acquired idiopathic (ai)- TTP patients in Japan with severe ADAMTS13 deficiency, noting that clinical and laboratory findings for ai-TTP patients in Japan differed from those for cohorts of ai-TTP patients in Europe and North America- raising concern that TTP findings vary by region of the world. (PLOS One 2011) We now on report clinical and laboratory characteristics of a cohort of TTP patients from Japan with tc-TTP, and compare these findings to three cohorts of tc-TTP in the United States and one cohort of ai-TTP patients from Japan. Methods: We queried a database of thrombotic microangiopathy patients identified from a national TTP referral laboratory in Japan of cases identified between 1998 and 2008. Severe ADAMTS13 deficiency was characterized by activity levels Results: Characteristics of ai- TTP with severe ADAMTS13 deficiency in Japan and tc-TTP in Japan and US Conclusions: These data from Japan validate insights about tc-TTP initially proposed in 1998, 1999, and 2000 in the United States. Ticlopidine is a likely cause of TTP, the mechanism is via a cross-reactive antibody to ADAMTS13:AC resulting in formation of an ADAMTS13:INH, and therapeutic plasma exchange is necessary for treatment. Disclosures: Ortel: Eisai: Research Funding; Glaxo SmithKline: Research Funding; Pfizer: Research Funding; Instrumentation Laboratory, Inc: Consultancy, Research Funding; Boehringer Ingelheim: Consultancy. Fujimura: Baxter BioScience: Membership on an entity9s Board of Directors or advisory committees; Alexion Pharma: Membership on an entity9s Board of Directors or advisory committees.
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gain of function ADAMTS13 variants that are resistant to autoantibodies against ADAMTS13 in patients with acquired thrombotic thrombocytopenic purpura
Blood, 2012Co-Authors: Cui Jian, Long X Zheng, Juan Xiao, Hau C Kwaan, Christopher G Skipwith, Shengyu Jin, Lingjie GongAbstract:Thrombotic thrombocytopenic purpura (TTP) is primarily caused by immunoglobulin G (IgG) autoantibodies against A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats, 13 (ADAMTS13). Nearly all adult idiopathic TTP patients harbor IgGs, which bind the spacer domain of ADAMTS13, a region critical for recognition and proteolysis of von Willebrand factor (VWF). We hypothesize that a modification of an exosite in the spacer domain may generate ADAMTS13 variants with reduced autoantibody binding while preserving or enhancing specific activity. Site-directed mutagenesis was used to generate a series of ADAMTS13 variants, and their functional properties were assessed. Of 24 novel ADAMTS13 variants, 2 (ie, M4, R660K/F592Y/R568K/Y661F and M5, R660K/F592Y/R568K/Y661F/Y665F) exhibited increased specific activity approximately 4- to 5-fold and approximately 10- to 12-fold cleaving a peptide VWF73 substrate and multimeric VWF, respectively. More interestingly, the gain-of-function ADAMTS13 variants were more resistant to inhibition by anti-ADAMTS13 autoantibodies from patients with acquired idiopathic TTP because of reduced binding by anti-ADAMTS13 IgGs. These results shed more light on the critical role of the exosite in the spacer domain in substrate recognition. Our findings also help understand the pathogenesis of acquired autoimmune TTP. The autoantibody-resistant ADAMTS13 variants may be further developed as a novel therapeutic for acquired TTP with inhibitors.
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multiple domains of ADAMTS13 are targeted by autoantibodies against ADAMTS13 in patients with acquired idiopathic thrombotic thrombocytopenic purpura
Haematologica, 2010Co-Authors: Long X Zheng, Charles L. Bennett, Dezhi Shang, Spero R Cataland, Erica M Falls, Christopher G Skipwith, Hau C KwaanAbstract:Background Type G immunoglobulins against ADAMTS13 are the primary cause of acquired (idiopathic) thrombotic thrombocytopenic purpura. However, the domains of ADAMTS13 which the type G anti-ADAMT13 immunoglobulins target have not been investigated in a large cohort of patients with thrombotic thrombocytopenic purpura. Design and Methods Sixty-seven patients with acquired idiopathic thrombotic thrombocytopenic purpura were prospectively collected from three major U.S. centers. An enzyme-linked immunosorbent assay determined plasma concentrations of anti-ADAMTS13 type G immunoglobulins, whereas immunoprecipitation plus western blotting determined the binding domains of these type G immunoglobulins. Results Plasma anti-ADAMTS13 type G immunoglobulins from 67 patients all bound full-length ADAMTS13 and a variant truncated after the eighth TSP1 repeat (delCUB). Approximately 97% (65/67) of patients harbored type G immunoglobulins targeted against a variant truncated after the spacer domain (MDTCS). However, only 12% of patients’ samples reacted with a variant lacking the Cys-rich and spacer domains (MDT). In addition, approximately 37%, 31%, and 46% of patients’ type G immunoglobulins interacted with the ADAMTS13 fragment containing TSP1 2-8 repeats (T2-8), CUB domains, and TSP1 5-8 repeats plus CUB domains (T5-8CUB), respectively. The presence of type G immunoglobulins targeted against the T2-8 and/or CUB domains was inversely correlated with the patients’ platelet counts on admission. Conclusions This multicenter study further demonstrated that the multiple domains of ADAMTS13, particularly the Cys-rich and spacer domains, are frequently targeted by anti-ADAMTS13 type G immunoglobulins in patients with acquired (idiopathic) thrombotic thrombocytopenic purpura. Our data shed more light on the pathogenesis of acquired thrombotic thrombocytopenic purpura and provide further rationales for adjunctive immunotherapy.
Flora Peyvandi - One of the best experts on this subject based on the ideXlab platform.
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ADAMTS13 mutations and polymorphisms in congenital thrombotic thrombocytopenic purpura
Human Mutation, 2010Co-Authors: Luca A Lotta, A. Cairo, R Palla, Isabella Garagiola, Flora PeyvandiAbstract:Congenital thrombotic thrombocytopenic purpura (TTP) (also known as Upshaw-Schulman syndrome, USS) is a rare, life-threatening disease characterized by thrombocytopenia and microangiopathic hemolytic anemia, associated with the deficiency of the von Willebrand factor-cleaving protease (ADAMTS13) due to mutations in the corresponding gene. The spectrum of clinical phenotype in congenital TTP is wide, encompassing neonatal-onset disease and adult-onset disease, forms with a single disease episode and chronic-relapsing forms. We review ADAMTS13 gene variants associated with inherited ADAMTS13 deficiency and congenital TTP. To date, 76 mutations of ADAMTS13 are reported in the literature. Missense mutations, which constitute nearly 60% of ADAMTS13 mutations, preferentially localize in the 5'-half of the gene encoding the N-terminal half of the protein, where the domains that are indispensable for ADAMTS13 catalytic function are situated. In vitro expression studies in cell cultures have shown that defects in protein secretion and catalytic activity are the main mechanisms responsible for the deficiency of ADAMTS13 in congenital TTP patients. Even if data from the literature suggest the existence of genotype-phenotype correlations, a clear relationship between the type and the effect of ADAMTS13 genetic defects with disease manifestations remains to be established.
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ADAMTS13 and anti ADAMTS13 antibodies as markers for recurrence of acquired thrombotic thrombocytopenic purpura during remission
Haematologica, 2008Co-Authors: Flora Peyvandi, Karen Vanhoorelbeke, Silvia Lavoretano, R Palla, Hendrik B Feys, Tullia Battaglioli, Carla Valsecchi, M T Canciani, Fabrizio Fabris, Samo ZverAbstract:Background From 20 to 50% of patients who survive an acute episode of the acquired form of thrombotic thrombocytopenic purpura relapse but clinical and laboratory markers of recurrence are not well established.Design and Methods In 109 patients enrolled in an international registry we evaluated, in the frame of a retrospective cohort study, the predictive role of the metalloprotease ADAMTS13 as measured in plasma during remission. Anti-ADAMTS13 antibodies and von Willebrand factor were also evaluated in a smaller number of the same patients.Results Median values of ADAMTS13 activity and antigen were significantly lower in patients with recurrent thrombotic thrombocytopenic purpura than in those with no recurrence (activity: 12% vs. 41%; p=0.007; antigen: 36% vs. 58%; p=0.003). A severe deficiency of ADAMTS13 activity (10% or less) was associated with a higher likelihood of recurrence (odds ratio 2.9; 95% confidence interval 1.3 to 6.8; p=0.01). Anti-ADAMTS13 antibodies were also more prevalent in patients with recurrent thrombotic thrombocytopenic purpura (odds ratio 3.1; 95% confidence interval 1.4 to 7.3; p=0.006). The presence during remission of both severe ADAMTS13 deficiency and anti-ADAMTS13 antibodies increased the likelihood of recurrence 3.6 times (95% confidence interval 1.4 to 9.0; p=0.006). The presence of ultralarge von Willebrand factor multimers and of associated diseases or conditions did not increase recurrence.Conclusions Survivors of an acute episode of acquired thrombotic thrombocytopenic purpura with severely reduced levels of ADAMTS13 and/or with anti-ADAMTS13 antibodies during remission have an approximately three-fold greater likelihood of developing another episode of thrombotic thrombocytopenic purpura than patients with higher protease activity and no antibody.
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ADAMTS13 autoantibodies in patients with thrombotic microangiopathies and other immunomediated diseases
Blood, 2005Co-Authors: Manfred Rieger, Flora Peyvandi, Klaus Zimmermann, Johanna Kremer A Hovinga, Inge Scharrer, Pier Mannuccio Mannucci, Andrea Herzog, Gabi Gerstenbauer, Christian Konetschny, M. GalbuseraAbstract:Autoantibodies neutralizing human ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type 1 motif), the metalloprotease that physiologically cleaves von Willebrand factor, are a major cause of severe deficiency of the protease and of acquired thrombotic thrombocytopenic purpura (TTP). We evaluated prevalence of anti-ADAMTS13 antibodies in 59 patients with thrombotic microangiopathies (TMAs) and in 160 patients with immunologic or thrombocytopenic diseases different from TTP, using an enzyme-linked immunosorbent assay (ELISA). Immunoglobulin G (IgG) antibodies directed against ADAMTS13 were found in 97% of untreated patients with acute acquired TMA who had plasma levels of ADAMTS13 activity below 10%. The corresponding prevalence of IgM antibodies was 11%. In contrast, anti-ADAMTS13 antibodies of G or M isotypes were detected in 20% of patients with TMA with ADAMTS13 activity above 10%. The ELISA was more sensitive than the standard functional inhibitor assay for detecting antibodies against ADAMTS13. Patients with thrombocytopenia from various causes (n = 50), systemic lupus erythematosus (SLE; n = 40), and the antiphospholipid antibody syndrome (APS; n = 55) had prevalences of IgG antibodies of 8%, 13%, and 5% respectively, only slightly higher than the prevalence in 111 healthy donors (4%). A rather high prevalence of anti-ADAMTS13 IgM antibodies was found in patients with SLE and APS (18% each). The clinical significance of IgM antibodies in these groups is unclear. In conclusion, the ELISA method detected anti-ADAMTS13 IgG antibodies in a very large proportion of patients with acquired TMA associated with severe ADAMTS13 deficiency, and was more sensitive than the inhibitor assay.
Mari Thomas - One of the best experts on this subject based on the ideXlab platform.
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pathogenicity of anti ADAMTS13 autoantibodies in acquired thrombotic thrombocytopenic purpura
EBioMedicine, 2015Co-Authors: Mari Thomas, Marie Scully, Rens De Groot, James T B CrawleyAbstract:Abstract Background Acquired thrombotic thrombocytopenic purpura (TTP) is an autoimmune disease in which anti-ADAMTS13 autoantibodies cause severe enzyme deficiency. ADAMTS13 deficiency causes the loss of regulation of von Willebrand factor multimeric size and platelet-tethering function, which results in the formation of disseminated microvascular platelet microthrombi. Precisely how anti-ADAMTS13 autoantibodies, or antibody subsets, cause ADAMTS13 deficiency (ADAMTS13 activity generally Methods We analysed 92 acquired TTP episodes at presentation, through treatment and remission/relapse using epitope mapping and functional analyses to understand the pathogenic mechanisms of anti-ADAMTS13 IgG. Results 89/92 of TTP episodes had IgG recognising the ADAMTS13 N-terminal domains. The central spacer domain was the only N-terminal antigenic target detected. 38/92 TTP episodes had autoantibodies recognising the N-terminal domains alone; 54/92 TTP episodes also had antibodies against the ADAMTS13 C-terminal domains (TSP2–8 and/or CUB domains). Changes in autoantibody specificity were detected in 9/16 patients at relapse, suggesting a continued development of the disease. Functional analyses on IgG from 43 patients revealed inhibitory IgG were limited to anti-spacer domain antibodies. However, 15/43 patients had autoantibodies with no detectable inhibitory action and as many as 32/43 patients had autoantibodies with inhibitory function that was insufficient to account for the severe deficiency state, suggesting that in many patients there is an alternative pathogenic mechanism. We therefore analysed plasma ADAMTS13 antigen levels in 91 acquired TTP presentation samples. We demonstrated markedly reduced ADAMTS13 antigen levels in all presentation samples, median 6% normal (range 0–47%), with 84/91 patients having Conclusions Anti-spacer domain autoantibodies are the major inhibitory antibodies in acquired TTP. However, depletion of ADAMTS13 antigen (rather than enzyme inhibition) is a dominant pathogenic mechanism. ADAMTS13 antigen levels at presentation have prognostic significance. Taken together, our results provide new insights into the pathophysiology of acquired TTP.
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a phenotype genotype correlation of ADAMTS13 mutations in congenital thrombotic thrombocytopenic purpura patients treated in the united kingdom
Journal of Thrombosis and Haemostasis, 2012Co-Authors: Raymond Camilleri, Marie Scully, Mari Thomas, I J Mackie, R Liesner, W Chen, K Manns, S J MachinAbstract:Background: ADAMTS13 mutations play a role in thrombotic thrombocytopenic purpura (TTP) pathogenesis. Objectives: To establish a phenotype-genotype correlation in a cohort of congenital TTP patients. Patients/Methods: Clinical history and ADAMTS13 activity, antigen and anti-ADAMTS13 antibody assays were used to diagnose congenital TTP, and DNA sequencing and in vitro expression were performed to identify the functional effects of the ADAMTS13 mutations responsible. Results: Seventeen (11 novel) ADAMTS13 mutations were identified in 17 congenital TTP patients. All had severely reduced ADAMTS13 activity and antigen levels at presentation. Six patients with pregnancy-associated TTP and six patients with childhood TTP were homozygous or compound heterozygous for ADAMTS13 mutations located in the metalloprotease (MP), cysteine-rich, spacer and/or distal thrombospondin type 1 domains. The adults had TTP precipitated by pregnancy, and had overall higher antigen levels (median, 30ngmL-1; range, <10-57ngmL-1) than the children (median, 14ngmL-1; range, <10-40ngmL-1). Presentation in the neonatal period was associated with more intensive treatment requirements. The two neonates with the most severe phenotype had mutations in the first thrombospondin type 1 motif of ADAMTS13 (p.R398C, p.R409W, and p.Q436H). Using transfected HEK293T cells, we have shown that p.R398C and p.R409W block ADAMTS13 secretion, whereas p.Q436H allows secretion at reduced levels. Conclusions: This study confirms the heterogeneity of ADAMTS13 defects and an association between ADAMTS13 genotypes and TTP phenotype. © 2012 International Society on Thrombosis and Haemostasis.