Procoagulant Platelet-Derived Microparticles Are Lower in Calreticulin-Than in-JAK2-Mutated Essential Thrombocythemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 110-110 ◽  
Author(s):  
Agnes Charpentier ◽  
Nathalie Cambier ◽  
Anne Bauters ◽  
Nathalie Trillot ◽  
Matthieu Wemeau ◽  
...  
Keyword(s):  
Essential Thrombocythemia ◽  
Lower Risk ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasm ◽  
Jak2 V617f ◽  
Procoagulant Activity ◽  
P Value ◽  
Thrombotic Risk ◽  
Testing Procedures ◽  
Increased Risk

Abstract Rationale: Essential Thrombocythemia (ET) is a Philadelphia-negative myeloproliferative neoplasm characterized by an increased risk of thrombosis. Previous reports suggest a role for microparticles (MP) in the pathogenesis of thrombosis in ET. MPs are small plasma membrane vesicles bearing potent procoagulant proteins and phospholipids. They are released into the circulation by various blood and endothelial cells after cellular activation and/or apoptosis. The recently described somatic calreticulin (CALR) exon 9 mutations in almost 20% of ET defines a lower-risk thrombosis ET subtype. We extensively studied phenotype and procoagulant activity of plasma MPs in order to assess MP contribution to the thrombotic risk in CALR versus JAK2 (V617F) mutated ET patients. Patients and methods: We analyzed MP count, phenotype and procoagulant activity in 45 JAK2 V617F+ and 15 CALR+ consecutive and newly diagnosed ET patients in accordance to WHO criteria recruited between november 2010 and april 2013. After given informed consent, blood samples were obtained in all patients before initiating any cytoreductive therapy. Pre-analytical and testing procedures complied with the recommendations of the ISTH Standardization Sub-Committee and each test was performed in duplicate . Using flow cytometry (FC500 flow-cytometer, Beckman-Coulter™), MPs were characterized and measured in platelet-free plasma samples. MPs were characterized by their size and co-expression of bound Annexin V and the following cell-specific monoclonal antibodies: CD41 (Platelet-MP, PMP), CD235a (Red cell-MP, RMP), CD14 (Monocytes-MP, MoMP), CD11b (Granulocytes-MP, GMP), CD144 (Endothelial-MP, EMP), CD62P and CD41 (P-Selectin+ PMP), CD142 and CD41 (Tissue Factor (TF)+ PMP, TF+PMP). MP-associated procoagulant activity was also measured using a-thrombin generation assay (Zymuphen™ MP-activity). Statistical analysis was performed with SPSS software. Results are expressed as median [interquartile range]. Results: Patients characteristics: The platelet count (109/L) was higher in CALR+ than in JAK2+ patients (866 [666 – 918], 659 [571 – 807] respectively, p= 0.049), and all other clinical and hematological characteristics were also distributed in agreement with previous reports. Furthermore, CALR+ patients were preferentially distributed in the lower risk categories of the IPSET-thrombosis and IPSET-survival scores than in JAK2+ patients (p<0.00001 and p= 0.04 respectively). The main results are summarized in table 1. MP count and MP/Platelets ratio were significantly lower in CALR+ than in JAK2+ patients. PMP count, PMP percentage of all MPs and PMP/Platelets ratio were lower in CALR+ than in JAK2+ patients. Furthermore, CALR+ patients had lower PMP surface P-Selectin. MP-associated procoagulant activity/Platelets ratio was significantly lower in CALR+ than in JAK2+ patients. There were no significant differences in TF-carrying PMP or in other cell-derived MP (RMP, MoMP, GMP, EMP). Conclusion: Our results demonstrate a decreased in circulating procoagulant PMP in CALR+ ET-patients compared to JAK2+ patients and lower platelet activation in CALR+ ET patients as measured by P-Selectin expression on PMP. Thus, as CALR+ patients have lower thrombotic-risk according to the literature and the IPSET-survival and IPSET-thrombosis scores observed in our study, the lower level of procoagulant PMP could account, at least in part, for a lower thrombotic risk of CALR+ ET patients. Table 1 main results CALR + JAK2 V617F + p value MP (/µL) 3289 [1662-4240] 4961 [2697-6687] 0.04 MP/Platelets 3.6 [2.8-5.3] 6.9 [4.7-9.6] 0.01 PMP (/µL) 3100 [2068–3887] 5702 [3423-10257] 0.004 PMP/Platelets 3.38 [2.97–6.33] 7.55 [5.12–12.66] 0.002 % PMP 90 [84–92] 93 [90–96] 0.03 MP-activity(nM)/platelet 0.015 [0.008–0.028] 0.029 [0.019–0.041] 0.05 P-Selectin+ PMP (/µL) 195 [152-219] 747 [383-965] 0.001 RMP (/µL) 4 [1.7–8.2] 4 [2.5–9.7] ns MoMP (/µL) 43 [27–52] 74.5 [22–135] ns GMP (/µL) 31.5 [24–48] 30 [11–55] ns EMP (/µL) 99.4 [32–110] 95.6 [51–140] ns TF+ PMP (/µL) 22.3 [9.8–115] 27.1 [20.8–94.4] ns Disclosures No relevant conflicts of interest to declare.

Screening JAK2 V617F-Negative and MPL W515K/L-Negative Essential Thrombocythemia Patients For Mutations In SESN2, DNAJC17, ST13, TOP1MT, and NTRK1

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5264-5264
Author(s):  
Carla AL Assaf ◽  
Els Lierman ◽  
Timothy Devos ◽  
Johan Billiet ◽  
Carlos Graux ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Recurrence Rate ◽  
Essential Thrombocythemia ◽  
Conflicts Of Interest ◽  
Single Cells ◽  
Myeloproliferative Neoplasm ◽  
Jak2 V617f ◽  
Driver Mutations ◽  
Potential Candidate ◽  
Dna Molecule

Abstract Background Essential thrombocythemia (ET) is a myeloproliferative neoplasm featured by a sustained elevation of platelet count and a tendency for thrombosis and hemorrhage. Cytogenetic abnormalities are rare in ET. The most common molecular abnormality in ET is JAK2 V617F, found in approximately 50% of ET cases followed by MPL W515K/L, found in about 10% of cases. The molecular cause of the remaining ET cases is still largely unknown. As such, in a substantial fraction of ET cases, the underlying molecular cause is yet to be discovered. In a recent study by Hou et al., single cells derived from an ET JAK2 V617F-negative ET patient were sequenced using a method based on exome sequencing. Eight genes were identified as possible candidate drivers. However, their recurrence rate in ET was not established. Aims To establish the recurrence rate in JAK2 V617F-negative and MPL W515K/L-Negative ET of potential candidate driver mutations, as identified by Hou et al. Methods and Results We studied unfractionated blood or bone marrow samples from a series of 64 cases of JAK2 V617F-negative and MPL W515K/L-negative ET. In this series, we used PCR and Sanger sequencing to detect the following mutations: SESN2 P87S, TOP1MT S479L, ST13 Q349*, and DNAJC17 A292P, as they exhibited the highest scores in the study of Hou et al. In addition, we included NTRK1 N323S, a mutant tyrosine kinase. None of the mutations reported by Hou et al. was detected in our patients. However, we identified a novel acquired heterozygous mutation in TOP1MT (c.1400 A>G, p.N467S) which is predicted to be damaging by polyphen 2. This mutation was not detected in the germline DNA from the buccal swab of the patient. TOP1MT is a mitochondrial topoisomerase encoded by the genomic DNA. It is a type IB enzyme, which sustains the appropriate conformation of DNA during replication, transcription, recombination, and repair. This mutation might affect the interaction of TOP1MT with the DNA molecule as suggested by the results of in silico analysis from I-Tasser. p.N467S mutation causes the gain of a helix and the loss of a β strand which are in close proximity to the bound DNA molecule. We screened exon 11 of TOP1MT gene in 38 additional JAK2 V617F-negative MPL W515K/L-negative ET cases, but did not find any additional cases. Conclusions In this series of 102 cases of JAK2 V617F-negative and MPL W515K/L-negative ET, only one case was identified with a mutation of TOP1MT. Mutations of SESN2, ST13, DNAJC17, or NTRK1, four other candidate driver genes as identified by Hou et al., could not be identified in a series of 64 cases. The functional role of TOP1MT in the pathogenesis of ET remains to be established. The absence of the mutations, as proposed by Hou et al., in our cohort raises questions about their role as potential driver mutations in JAK2 V617F-negative and MPL W515K/L-negative ET. The quest for the full complement of driver mutations in ET therefore remains open. Reference Hou, Y., et al., Single-cell exome sequencing and monoclonal evolution of a JAK2-negative myeloproliferative neoplasm. Cell, 2012. 148(5): p. 873-85. Disclosures: No relevant conflicts of interest to declare.

scholarly journals What’s in a Number? Examining the Prognostic and Predictive Importance of Platelet Count in Patients With Essential Thrombocythemia

2020 ◽  
Vol 18 (9) ◽  
pp. 1279-1284
Author(s):  
Andrew T. Kuykendall ◽  
Rami Komrokji
Keyword(s):  
Platelet Count ◽  
Essential Thrombocythemia ◽  
Myeloproliferative Neoplasm ◽  
Consensus Guidelines ◽  
Thrombotic Risk ◽  
Increased Risk ◽  
Hemorrhagic Events ◽  
Platelet Number ◽  
Mutation Age ◽  
Shed Light

Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by clonal overproduction of platelets and an increased risk of thrombohemorrhagic complications. Patients are risk stratified by driver mutation, age, and thrombotic history and treated to reduce the risk of thrombotic and hemorrhagic events. The significance of platelet number as a risk factor or treatment goal is unclear. Despite the preponderance of data failing to demonstrate an association, there exists a pervasive belief that higher platelet counts correlate with an increased thrombotic risk. In fact, the association between thrombocytosis and bleeding is more clearly supported. Variability in regional consensus guidelines contributes to the uncertainty. This article reviews the data that shed light on the importance of platelet count in patients with ET.

scholarly journals PEAR1 Genetic Variants in Essential Thrombocythemia: A New Study of The Prevalence and Association of PEAR1 Variants with Hematological Parameters and ET Mutations

2021 ◽  
Author(s):  
Mohsen Maleknia ◽  
Mohammad Taha Jalali ◽  
Gholam Abbas Kaydani ◽  
Ahmad Ahmadzadeh ◽  
Najmaldin Saki
Keyword(s):  
Platelet Count ◽  
Essential Thrombocythemia ◽  
Significant Relationship ◽  
Hematological Parameters ◽  
Myeloproliferative Neoplasm ◽  
Pcr Amplification ◽  
Jak2 V617f ◽  
P Value ◽  
Arms Pcr ◽  
Calr Mutation

Abstract Objective: Essential thrombocythemia (ET) is a type of myeloproliferative neoplasm characterized by the expansion of the megakaryocytic/platelet line. Given the undeniable role of genetic variations in the pathogenesis of ET, as well as the proven effects of PEAR1 SNPs on platelet function, the innovative purpose of this study is to investigate the prevalence of PEAR1 variants (rs12041331 and rs12566888) and their relationship to hematological parameters and ET-related mutations.Materials and Methods: We studied 105 ET patients and analyzed ET patients' mutational profiles, including JAK2 V617F mutation (detected by Allele-specific PCR), CALR, and MPL mutations (both through PCR amplification). Two SNPs of the PEAR1 gene were assessed through ARMS-PCR, and the Sanger method was used for the validation of ARMS-PCR amplification.Results: The prevalence of rs12041331 and rs12566888 in ET patients were 43.9% and 38.5%, respectively, and rs12041331 was significantly associated with increased platelet counts (P-Value: 0.02). A significant relationship was also found between the rs12041331 and CALR mutation (P-Value: 0.03). Platelet count was higher in CALR+ patients (934.45 ×10 9/L ± 265.35 SD) than in JAK2 + patients (790.11 ×10 9/L ± 265.35 SD). Conversely, other hematological parameters and thrombosis were higher in JAK2 + patients than the CALR + patients.Conclusions: Our findings reinforce the idea that rs12041331 and rs12566888 may be associated with ET, and rs12041331 is significantly associated with increased platelet count. Besides, the prevalence of ET-related mutations in patients with rs12041331 and rs12566888 was almost similar; however, only CALR mutation had a significant relationship with rs12041331.

Oxidative Stress Levels, JAK2V617F Mutational Status and Thrombotic Complications in Patients with Essential Thrombocythemia

2019 ◽  
Vol 70 (8) ◽  
pp. 2822-2825 ◽  
Author(s):  
Cornel Moisa ◽  
Mihnea Alexandru Gaman ◽  
Camelia Cristina Diaconu ◽  
Amelia Maria Gaman
Keyword(s):  
Oxidative Stress ◽  
Essential Thrombocythemia ◽  
Myeloproliferative Neoplasm ◽  
Oxygen Species ◽  
Mutational Status ◽  
Increased Risk ◽  
Stress Levels ◽  
Total Antioxidant ◽  
Thrombotic Complications ◽  
The Relationship

Essential thrombocythemia (ET) is a BCR-ABL1-negative myeloproliferative neoplasm associated with thrombotic and haemorrhagic complications. Reactive oxygen species (ROS) overexpression induces a growth advantage to JAK2V617F-positive clones and, in association with a higher number of immature platelets, leukocytosis, and additional cardiovascular risk factors, leads to an increased risk for thrombotic events. We evaluated oxidative stress by measuring ROS levels and the total antioxidant capacity (TAC) in 62 ET patients and investigated the relationship between oxidative stress, JAK2V617F mutational status and the development of thrombotic events. We found higher oxidative stress levels in JAK2V617F-positive vs. JAK2V617F-negative ET cases with no significant differences between homozygous and heterozygous genotypes. Increased ROS levels and thrombotic events were more frequent in ET patients with old age at diagnosis, higher haematocrit levels or leukocytosis.

Successful thrombolysis in essential thrombocythemia-related acute ischaemic stroke

2021 ◽  
Vol 14 (5) ◽  
pp. e242925
Author(s):  
Ishita Desai ◽  
Ashutosh Tiwari ◽  
Mritunjai Kumar Singh ◽  
Niraj Kumar
Keyword(s):  
Ischaemic Stroke ◽  
Essential Thrombocythemia ◽  
Acute Ischaemic Stroke ◽  
Jak2 V617f ◽  
Preliminary Evidence ◽  
Sudden Onset ◽  
Left Ventricular ◽  
Interesting Case ◽  
Increased Risk ◽  
Successful Thrombolysis

Essential thrombocythemia (ET)-related acute ischaemic stroke (AIS) may account for approximately 0.25%–0.5% of all ischaemic strokes. If left undiagnosed and untreated, patients with ET carry an increased risk of recurrent thrombosis involving major organs including the brain. We report an interesting case of a 67-year-old man, who was successfully thrombolysed for AIS resulting from ET. He presented with sudden onset of left-sided hemiparesis with a left-ventricular clot. His subsequent investigations including positive JAK2 V617F mutation confirmed the diagnosis of ET. He made a significant recovery with thrombolysis, anticoagulation, antiplatelet and hydroxyurea. A fear of post-thrombolytic haemorrhagic complications appears the major reason for the lack of reports of thrombolysis in ET-related AIS. Although the diagnosis of ET was confirmed on subsequent investigations, successful thrombolysis in our case provides preliminary evidence that ET-related AIS cases can undergo successful thrombolysis using tenecteplase. To date, ours is only the second case of ET-related AIS being thrombolysed.

scholarly journals Impact of Labor Induction at 39 Weeks Gestation Compared with Expectant Management on Maternal and Perinatal Morbidity among a Cohort of Low-risk Women

2021 ◽  
Author(s):  
Sabrina C. Burn ◽  
Ruofan Yao ◽  
Maria Diaz ◽  
Jordan Rossi ◽  
Stephen Contag
Keyword(s):  
Cesarean Delivery ◽  
Lower Risk ◽  
Fetal Death ◽  
Expectant Management ◽  
Low Risk ◽  
P Value ◽  
Cesarean Hysterectomy ◽  
Increased Risk ◽  
Nicu Admission ◽  
Low Risk Women

Abstract Objective: To determine rates of maternal and perinatal outcomes after induction of labor (IOL) at 39 weeks compared with expectant management.Methods: Cohort study of low risk women delivered between 39-42 weeks from 2015 to 2018. We excluded births with fetal abnormalities, previous cesarean, multiple pregnancies or those with spontaneous onset of labor (SOL) or indicated delivery at 39 weeks. Data was abstracted from National Center for Health Statistics birth files. Relative risks (aRR) were estimated with multivariable log-binomial regression. Main Outcome Measures: Maternal outcomes: chorioamnionitis (Triple I), blood transfusion, neonatal intensive care unit (NICU) admission, uterine rupture, cesarean delivery and cesarean hysterectomy. Fetal and infant outcomes: fetal death, 5-minute Apgar ≤3, prolonged ventilation, seizures, ICU admission, and death within 28 days. Results: There were 15,900,956 births, with 8,540,063 after exclusions. The IOL group included 1,177,790 births excluding women with diabetes or hypertensive disease. There were 3,835,185 births after 39 weeks excluding women with diabetes or chronic hypertension. With IOL at 39 weeks the risk for blood transfusion (p-value < 0.01; aRR 0.78; 95% CI [0.75-0.82]), Triple I (p-value < 0.01; aRR 0.71; 95% CI [0.70-0.73]) and cesarean delivery (p-value <0.01; aRR 0.87; 95% CI [0.87-0.88]) were lower, albeit increased risk of cesarean hysterectomy (p-value <0.01; aRR 1.23; 95% CI [1.07-1.41]). Neonates had a lower risk for 5-minute Apgar ≤3 (p-value < 0.01; aRR 0.68; 95% CI [0.66-0.71]), prolonged ventilation (p-value < 0.01; aRR 0.84; 95% CI [0.81-0.87]), NICU admission (p-value < 0.01; aRR 0.86; 95% CI [0.85-0.87]), and neonatal seizures (p-value <0.01; aRR 0.85; 95% CI [0.76-0.96]). There was no difference in risk for neonatal death 0.99% (p-value 0.99; aRR 1.00; 95%CI [0.99-1.00]), or fetal death (p-value 0.78; aRR 1.0002; 95%CI [0.99-1.002]. This benefit was greater compared with each subsequent week.Conclusions: Induction of labor at 39 weeks of gestation in a low risk cohort is associated a lower risk of cesarean delivery, transfusions and infection, as well as lower neonatal morbidity, without difference in fetal or neonatal death. This appears to be associated with increased risk for cesarean hysterectomy.

scholarly journals JAK2 V617F impairs hematopoietic stem cell function in a conditional knock-in mouse model of JAK2 V617F–positive essential thrombocythemia

Blood ◽  
2010 ◽  
Vol 116 (9) ◽  
pp. 1528-1538 ◽  
Author(s):  
Juan Li ◽  
Dominik Spensberger ◽  
Jong Sook Ahn ◽  
Shubha Anand ◽  
Philip A. Beer ◽  
...  
Keyword(s):  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Essential Thrombocythemia ◽  
Cell Function ◽  
Myeloproliferative Neoplasms ◽  
Myeloproliferative Neoplasm ◽  
Jak2 V617f ◽  
Transgenic Models ◽  
Disease Phenotype ◽  
Hematopoietic Stem

The JAK2 V617F mutation is found in most patients with a myeloproliferative neoplasm and is sufficient to produce a myeloproliferative phenotype in murine retroviral transplantation or transgenic models. However, several lines of evidence suggest that disease phenotype is influenced by the level of mutant JAK2 signaling, and we have therefore generated a conditional knock-in mouse in which a human JAK2 V617F is expressed under the control of the mouse Jak2 locus. Human and murine Jak2 transcripts are expressed at similar levels, and mice develop modest increases in hemoglobin and platelet levels reminiscent of human JAK2 V617F–positive essential thrombocythemia. The phenotype is transplantable and accompanied by increased terminal erythroid and megakaryocyte differentiation together with increased numbers of clonogenic progenitors, including erythropoietin-independent erythroid colonies. Unexpectedly, JAK2V617F mice develop reduced numbers of lineage−Sca-1+c-Kit+ cells, which exhibit increased DNA damage, reduced apoptosis, and reduced cell cycling. Moreover, competitive bone marrow transplantation studies demonstrated impaired hematopoietic stem cell function in JAK2V617F mice. These results suggest that the chronicity of human myeloproliferative neoplasms may reflect a balance between impaired hematopoietic stem cell function and the accumulation of additional mutations.

Increased risk of heparin induced thrombocytopenia and thrombosis in patients with essential thrombocythemia carrying the homozygous JAK2 V617F mutation

2018 ◽  
Vol 47 (1) ◽  
pp. 155-156 ◽  
Author(s):  
Roberto Castelli ◽  
Paolo Gallipoli ◽  
Riccardo Schiavon ◽  
Thomas Teatini ◽  
Giorgio Lambertenghi Deliliers ◽  
...  
Keyword(s):  
Essential Thrombocythemia ◽  
Jak2 V617f ◽  
Jak2 V617f Mutation ◽  
Heparin Induced Thrombocytopenia ◽  
Increased Risk ◽  
V617f Mutation

scholarly journals Thrombocytosis: Diagnostic Evaluation, Thrombotic Risk Stratification, and Risk-Based Management Strategies

Thrombosis ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
Jonathan S. Bleeker ◽  
William J. Hogan
Keyword(s):  
Polycythemia Vera ◽  
Essential Thrombocythemia ◽  
Myeloproliferative Neoplasms ◽  
Treatment Options ◽  
Treatment Strategies ◽  
Diagnostic Evaluation ◽  
Diagnostic Process ◽  
Special Focus ◽  
Thrombotic Risk ◽  
Increased Risk

Thrombocytosis is a commonly encountered clinical scenario, with a large proportion of cases discovered incidentally. The differential diagnosis for thrombocytosis is broad and the diagnostic process can be challenging. Thrombocytosis can be spurious, attributed to a reactive process or due to clonal disorder. This distinction is important as it carries implications for evaluation, prognosis, and treatment. Clonal thrombocytosis associated with the myeloproliferative neoplasms, especially essential thrombocythemia and polycythemia vera, carries a unique prognostic profile, with a markedly increased risk of thrombosis. This risk is the driving factor behind treatment strategies in these disorders. Clinical trials utilizing targeted therapies in thrombocytosis are ongoing with new therapeutic targets waiting to be explored. This paper will outline the mechanisms underlying thrombocytosis, the diagnostic evaluation of thrombocytosis, complications of thrombocytosis with a special focus on thrombotic risk as well as treatment options for clonal processes leading to thrombocytosis, including essential thrombocythemia and polycythemia vera.

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