Search results for "MTS1"
showing 10 items of 28 documents
Late onset and pregnancy-induced congenital thrombotic thrombocytopenic purpura
2014
SummaryWe report on our patient (case 2) who experienced a first acute episode of thrombotic thrombocytopenic purpura (TTP) at the age of 19 years during her first pregnancy in 1976 which ended in a spontaneous abortion in the 30th gestational week. Treatment with red blood cell concentrates was implemented and splenectomy was performed. After having suffered from several TTP episodes in 1977, possibly mitigated by acetylsalicylic acid therapy, an interruption and sterilization were performed in 1980 in her second pregnancy thereby avoiding another disease flare-up. Her elder sister (case 1) had been diagnosed with TTP in 1974, also during her first pregnancy. She died in 1977 during her se…
Open ADAMTS13, induced by antibodies, is a biomarker for subclinical immune-mediated thrombotic thrombocytopenic purpura
2020
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 con…
Expression of the Tumor Suppressor Gene Product p16INK4 in Benign and Malignant Melanocytic Lesions
1998
The gene MTS1 encodes p16INK4, an inhibitor of cyclin-dependent kinase 4, and is frequently deleted, mutated, or silenced by promoter methylation in melanoma cells and in the germline of familial melanoma patients. Although MTS1 may thus be the candidate melanoma suppressor gene that maps to chromosome 9p21, it is not clear how dysfunction at that locus temporally relates to melanoma progression. To further test its role in sporadic melanoma, the expression of p16INK4-protein and -mRNA was characterized in melanomas and melanocytic nevi by immunocytochemistry and in situ reverse transcriptase-polymerase chain reaction. Histologic tissue sections were immunolabeled with anti-p16INK4 antibody…
Reversible posterior leukoencephalopathy syndrome in a patient with thrombotic thrombocytopenic purpura
2011
Thrombotic thrombocytopenic purpura (TTP) is an autoimmune disorder characterised by fever, microangiopathic haemolytic anaemia, renal insufficiency, and thrombocytopenia. Neurological involvement, a prominent component of TTP, is characterised by a variety of brain lesions which include reversible cerebral oedema or magnetic resonance imaging (MRI) features of reversible posterior leukoencephalopathy syndrome (RPLS). TTP is frequently associated with deficiency of the von Willebrand factor-cleaving protease, ADAMTS13.Here, we report a case of TTP with severe acute encephalopathy. Posterior leukoencephalopathy and brainstem oedema with triventricular hydrocephalus were observed on MRI. The …
Anti-ADAMTS13 autoantibody profiling in patients with immune-mediated thrombotic thrombocytopenic purpura.
2021
Anti-A Disintegrin and Metalloproteinase with a ThromboSpondin type 1 motif, member 13 (ADAMTS13) autoantibodies cause a severe ADAMTS13 deficiency in immune-mediated thrombotic thrombocytopenic purpura (iTTP). ADAMTS13 consists of a metalloprotease (M), a disintegrin-like (D) domain, 8 thrombospondin type 1 repeats (T1-T8), a cysteine-rich (C), a spacer (S), and 2 CUB domains (CUB1-2). We recently developed a high-throughput epitope mapping assay based on small, nonoverlapping ADAMTS13 fragments (M, DT, CS, T2-T5, T6-T8, CUB1-2). With this assay, we performed a comprehensive epitope mapping using 131 acute-phase samples and for the first time a large group of remission samples (n = 50). Ne…
Safety of Caplacizumab in Patients Without Documented Severe ADAMTS13 Deficiency During the HERCULES Study
2019
Background: Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare, life-threatening autoimmune thrombotic microangiopathy caused by a deficiency in the activity of ADAMTS13 leading to the formation of ultra-large multimers of von Willebrand factor (vWF) and abnormal platelet adhesion in the microvasculature. aTTP requires prompt diagnosis and rapid initiation of treatment to limit the risk of negative or fatal outcomes. The clinical diagnosis of aTTP is based on thrombocytopenia and microangiopathic hemolytic anemia and is confirmed by ADAMTS13 <10%. However, the latter confirmation is not always rapidly available, and treatment is typically initiated based on the clinical diagno…
A critical evaluation of caplacizumab for the treatment of acquired thrombotic thrombocytopenic purpura
2020
Introduction: Acquired thrombotic thrombocytopenic purpura (aTTP) is a thrombotic microangiopathy caused by inhibitory autoantibodies against ADAMTS13 protein. Until recently, the combination of plasma exchange (PEX) and immunosuppression has been the standard front-line treatment in this disorder. However, aTTP-related mortality, refractoriness, and relapse are still a matter of concern. Areas covered: The better understanding of the pathophysiological mechanisms of aTTP has allowed substantial improvements in the diagnosis and treatment of this disease. Recently, the novel anti-VWF nanobody caplacizumab has been approved for acute episodes of aTTP. Caplacizumab is capable to block the adh…
COVID-19 as a Potential Trigger for Immune Thrombotic Thrombocytopenic Purpura and Reason for an Unusual Treatment: A Case Report
2021
AbstractImmune thrombotic thrombocytopenic purpura (iTTP) is a rare autoimmune disorder characterized by severely reduced activity of the von Willebrand factor (VWF)-cleaving protease ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) due to autoantibodies. This leads to the development of pathogenic multimers of VWF, causing a thrombotic microangiopathy with decreased number of platelets, hemolysis, and life-threatening tissue ischemia of mostly brain, heart, and kidneys. Standard treatment of iTTP involves daily plasma exchange to remove ultra large multimers of VWF, inhibitors, substituting ADAMTS13, and the accompaniment of an immunosuppressive …
Immunogenic hotspots in the spacer domain of ADAMTS13 in immune‐mediated thrombotic thrombocytopenic purpura
2021
International audience; Background 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, th…
ADAMTS13 and VWF activities guide individualized caplacizumab treatment in patients with aTTP
2020
Abstract Introduction of the nanobody caplacizumab was shown to be effective in the treatment of acquired thrombotic thrombocytopenic purpura (aTTP) in the acute setting. The official recommendations include plasma exchange (PEX), immunosuppression, and the use of caplacizumab for a minimum of 30 days after stopping daily PEX. This study was a retrospective, observational analysis of the use of caplacizumab in 60 patients from 29 medical centers in Germany. Immunosuppressive treatment led to a rapid normalization of ADAMTS13 activities (calculated median, 21 days). In 35 of 60 patients, ADAMTS13 activities started to normalize before day 30 after PEX; in 11 of 60 patients, the treatment was…