scholarly journals Interrelationship between ADAMTS13 activity, von Willebrand factor, and complement activation in remission from immune‐mediated trhrombotic thrombocytopenic purpura

2020 ◽  
Vol 189 (1) ◽  
Author(s):  
Haiwa Wu ◽  
Lauren Jay ◽  
Shili Lin ◽  
Chenggong Han ◽  
Shangbin Yang ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Complement Activation ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Immune Mediated ◽  
Von Willebrand ◽  
Willebrand Factor

von Willebrand factor cleaving protease (ADAMTS13) is deficient in recurrent and familial thrombotic thrombocytopenic purpura and hemolytic uremic syndrome

Blood ◽  
2002 ◽  
Vol 100 (3) ◽  
pp. 778-785 ◽  
Author(s):  
Giuseppe Remuzzi ◽  
Miriam Galbusera ◽  
Marina Noris ◽  
Maria Teresa Canciani ◽  
Erica Daina ◽  
...  
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Acute Phase ◽  
Von Willebrand Factor ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Uremic Syndrome ◽  
Adamts13 Deficiency ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Whether measurement of ADAMTS13 activity may enable physicians to distinguish thrombotic thrombocytopenic purpura (TTP) from hemolytic uremic syndrome (HUS) is still a controversial issue. Our aim was to clarify whether patients with normal or deficient ADAMTS13 activity could be distinguished in terms of disease manifestations and multimeric patterns of plasma von Willebrand factor (VWF). ADAMTS13 activity, VWF antigen, and multimeric pattern were evaluated in patients with recurrent and familial TTP (n = 20) and HUS (n = 29). Results of the collagen-binding assay of ADAMTS13 activity were confirmed in selected samples by testing the capacity of plasma to cleave recombinant VWF A1-A2-A3. Most patients with TTP had complete or partial deficiency of ADAMTS13 activity during the acute phase, and in some the defect persisted at remission. However, complete ADAMTS13 deficiency was also found in 5 of 9 patients with HUS during the acute phase and in 5 patients during remission. HUS patients with ADAMTS13 deficiency could not be distinguished clinically from those with normal ADAMTS13. In a subgroup of patients with TTP or HUS, the ADAMTS13 defect was inherited, as documented by half-normal levels of ADAMTS13 in their asymptomatic parents, consistent with the heterozygous carrier state. In patients with TTP and HUS there was indirect evidence of increased VWF fragmentation, and this occurred also in patients with ADAMTS13 deficiency. In conclusion, deficient ADAMTS13 activity does not distinguish TTP from HUS, at least in the recurrent and familial forms, and it is not the only determinant of VWF abnormalities in these conditions.

scholarly journals Active and Ultra-Large Von Willebrand Factor Is Significantly Elevated in Patients with Immune Thrombotic Thrombocytopenic Purpura

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 523-523
Author(s):  
Wenjing Cao ◽  
Alicia Veninga ◽  
Elizabeth M. Staley ◽  
Adam Miszta ◽  
Nicole Kocher ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand Factor ◽  
Plasma Levels ◽  
Acute Episode ◽  
Healthy Controls ◽  
Plasma Samples ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Background: Immune thrombotic thrombocytopenic purpura (iTTP), a potentially fatal hematological emergency, is primarily caused by acquired deficiency of ADAMTS13 activity due to autoantibodies. Immunoglobulin G (IgG)-type autoantibodies bind ADAMTS13 and inhibit its ability to cleave endothelium-derived ultra large von Willebrand factor (ULVWF). However, it remains poorly understood whether plasma VWF status can be used as a disease marker for diagnosis and monitoring therapy in patients with acute iTTP. Objective: To address this question, we determined plasma levels of VWF antigen (VWF:Ag), collagen-binding activity (VWF:CB), active forms of VWF (VWF:Ac), and VWF multimers in iTTP patients during acute episode and in early remission. Patients and Methods: From the Alabama registry, we identified 69 unique patients with a confirmed diagnosis of iTTP in whom plasma ADAMTS13 activity was <10 U/dL with positive inhibitors and elevated anti-ADAMTS13 IgGs. Of 69 patients, 21 had longitudinal plasma samples collected. Plasma samples from 56 healthy individuals, who did not have a hematological disease, cancer, and infection, were recruited as controls. Plasma levels of VWF:Ag, VWF:CB, and VWF:Ac were determined by an ELISA-based assay. Plasma VWF multimer distribution was assessed by an in-gel Western blotting assay following electrophoresis on a 1% SDS-agarose gel. Results: The mean age for our cohort iTTP patients was 43.9 ± 13.4 years. Twenty-six patients were male and 43 were female with male to female ratio of 1 to 1.7. Fifty-three patients were African American descents, 14 Caucasians, 1 Hispanic, and 1 unknown race. Plasma levels of VWF:Ag in acute iTTP patients were 289.4 ± 17.7%, significantly increased compared with those in the healthy controls (144.9 ± 7.6%) (p<0.0001); plasma levels of VWF:CB in these patients were 241 ± 17.9%, also significantly elevated compared with those in the healthy controls (149.9 ± 12.01%) (p=0.0001); additionally, plasma levels of VWF:Ac (304.6 ± 23.2%), assessed by its ability to bind anti-VWF-A1 nanobody, were more dramatically elevated compared with those in the controls (101.6 ± 5.9%) (p<0.0001). More interestingly, while the ratios of VWF:CB to VWF:Ag in patients with acute iTTP (0.8 ± 0.04) were lower than those in the healthy controls (1.0 ± 0.05) (p=0.0036), the ratios of VWF:Ac to VWF:Ag were significantly higher in patients with acute episode (1.2 ± 0.1) than those in the controls (0.8 ± 0.05) (p=0.0003). Furthermore, there was no statistically significant difference in the patient plasma levels of VWF:Ag (p=0.69) and VWF:CB (p=0.08) during acute episode and during early remission. However, the plasma levels of VWF:Ac in patients with acute disease were significantly higher than those in the early remission (p=0.002). Surprisingly, 90% (36/40) of out iTTP patients during acute episode showed the presence of ULVWF in their plasma using in-gel Western blotting, which allows the ULVWF to be detected without the transfer step to avoid any potential loss of larger VWF multimers during protein transfer. These ULVWF multimers disappeared in 3/4 iTTP patients in remission when ADAMTS13 activity recovered. In 28 healthy control samples, only one showed ULVWF. Conclusion: Our results demonstrate, for the first time in a large cohort, that active forms of VWF and ultra large VWF multimers are present in iTTP patient's plasma during the acute period, which is reduced or disappears during the early remission. Therefore, measuring active forms of VWF and ultra large VWF multimers may aid in diagnosis of iTTP and help monitoring of disease processes following therapy. Our ongoing study is to determine whether these biomarkers can be used to predict responses to treatment and long-term outcome. Disclosures Zheng: Alexion: Research Funding, Speakers Bureau.

scholarly journals A Quantitative Assay of In Vivo Cleavage of Von Willebrand Factor By ADAMTS13 Reveals Excessive Cleavage in Type 2B Von Willebrand Disease and Diminished Cleavage in Thrombotic Thrombocytopenic Purpura

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2532-2532
Author(s):  
Xiaoyun Fu ◽  
Mallory N. Pahl ◽  
Yi Wang ◽  
Barbara A. Konkle ◽  
Junmei Chen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Von Willebrand Factor ◽  
Peptide Bond ◽  
Von Willebrand Disease ◽  
Adamts13 Activity ◽  
Small Peptide ◽  
Thrombocytopenic Purpura ◽  
Normal Plasma ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Von Willebrand Factor (VWF) is a large glycoprotein that plays a crucial role in hemostasis by enabling platelets to adhere to sites of vascular injury, particularly under conditions of high shear stress. The multimeric structure of VWF is central to its activity; VWF is most active in its ultra-large multimer form (ULVWF). The size of plasma VWF is regulated by the plasma metalloprotease ADAMTS13, which cleaves VWF at the Tyr1605-Met1606 peptide bond within the A2 domain. Abnormal VWF cleavage has been implicated in a wide range of thrombotic and bleeding disorders, including thrombotic thrombocytopenic purpura (TTP) and Type 2 von Willebrand disease (VWD). These two diseases represent extreme phenotypes of VWF proteolysis-the former with too little cleavage and the latter with too much cleavage. ADAMTS13 proteolysis of VWF is currently assessed by either multimer gel analysis or ADAMTS13 activity assays. High-resolution agarose gels give an estimate of the extent to which a particular band represents cleaved vs native VWF. This method, however, is not quantitative and cannot distinguish whether a particular cleavage product is produced by ADAMTS13 or by another protease. Alternatively, ADAMTS13 activity assays are indirect measures of VWF cleavage, used especially to diagnose TTP. These assays measure the extent to which a subject's ADAMTS13 can cleave an exogenous substrate, usually a small peptide, and do not determine the extent of endogenous VWF cleavage. Therefore, we developed a mass spectrometry-based method to directly quantify cleavage of the Tyr1605-Met1606 peptide bond in plasma VWF. Here, we report quantification of VWF cleavage in plasma from normal donors, and TTP and VWD patients. Methods: VWF was isolated from plasma by immunoprecipitation using polyclonal VWF antibody and then digested with trypsin. Tryptic peptides, including the ADAMTS13-cleaved peptide and a control peptide, were quantified by nano ultra-performance liquid chromatography tandem mass spectrometry (nanoLC-MS/MS) using heavy isotope-labelled peptides as internal standards. The extent of VWF cleavage by ADAMTS13 was determined as the concentration ratio of ADAMTS13-cleaved peptide to a control peptide representative of total VWF, and expressed as percent cleavage. Results: Given that the plasma concentration of VWF is relatively low, we first optimized conditions for sample preparation and analysis. Using NanoLC-MS/MS with isotopic dilution, we quantified ADAMTS13 cleavage of VWF in plasma samples (10-100 µl) containing 100-500 ng of VWF. We tested the reproducibility of the measurement using pooled normal plasma. The quantification was highly reproducible, with a wide linear range. VWF cleavage in pooled normal plasma was 4.9% ± 0.3% (mean ± SD, n=6), indicating that one VWF monomer in 20 is cleaved, on average. Cleavage was much higher in plasma from type 2B VWD patients (n=5), ranging from 15-30% depending on mutations. In contrast, we observed only 2.1-3.2% (n=6) cleavage in plasma VWF from TTP patients. Summary: This is the first report of quantification of ADAMTS13-mediated VWF cleavage in plasma. In normal plasma, approximately 5% of VWF A2 domains are cleaved, whereas cleavage was reduced to approximately 60% of normal on average in 6 TTP patients, and increased up to 6 times normal in patients with Type 2B VWD. In TTP, this level of proteolysis would be expected to result in accumulation of ULVWF multimers, as only between 1 in 50 to 1 in 30 monomers were cleaved. In type 2B VWD, by contrast, proteolysis may play a much larger role in the lack of larger multimers than previously appreciated, as up to 1 in 3 monomers were cleaved. This method should also prove useful in conditions such as severe malaria, in which it has been suggested that VWF cleavage is impaired, but this is not necessarily accompanied by low ADAMTS13 activity as measured with a small peptide substrate. Disclosures No relevant conflicts of interest to declare.

Von Willebrand factor–cleaving protease (ADAMTS13) in thrombocytopenic disorders: a severely deficient activity is specific for thrombotic thrombocytopenic purpura

Blood ◽  
2002 ◽  
Vol 100 (2) ◽  
pp. 710-713 ◽  
Author(s):  
Valentina Bianchi ◽  
Rodolfo Robles ◽  
Lorenzo Alberio ◽  
Miha Furlan ◽  
Bernhard Lämmle
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand Factor ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Heparin Induced Thrombocytopenia ◽  
Severe Deficiency ◽  
Uremic Syndrome ◽  
Adamts13 Deficiency ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract A severe deficiency in von Willebrand factor–cleaving protease (ADAMTS13) activity (&lt; 5% that in normal plasma) has been observed in most patients with a diagnosis of thrombotic thrombocytopenic purpura (TTP) but not in those with a diagnosis of hemolytic uremic syndrome. However, ADAMTS13 deficiency has been claimed not to be specific for TTP, since it was observed in various thrombocytopenic and other conditions. We studied 68 patients with thrombocytopenia due to severe sepsis or septic shock (n = 17), heparin-induced thrombocytopenia (n = 16), idiopathic thrombocytopenic purpura (n = 10), or other hematologic (n = 15) or miscellaneous conditions (n = 10). Twelve of the 68 patients had subnormal levels of ADAMTS13 activity (≤ 30%), but none had less than 10%. Thus, the study showed that ADAMTS13 activity is decreased in a substantial proportion of patients with thrombocytopenia of various causes. A severe deficiency of ADAMTS13 (&lt; 5%), identified in more than 120 patients during 1996 to 2001 in our laboratory, is specific for a thrombotic microangiopathy commonly labeled TTP.

Sign in / Sign up

Export Citation Format

Share Document