Polycythemia Vera: Scientific Advances and Current Practice

Raman spectroscopy-based biomarker screening by studying the fingerprint and lipid characteristics of Polycythemıa Vera cases blood serum

This study aimed to develop a novel approach for diagnosing Polycythemia Vera (PV), a stem cell-derived neoplasm of the myeloid lineage. The approach utilized Raman spectroscopy coupled with multivariate analysis to analyze blood serum samples collected from PV patients. The results showed that PV serum exhibited lower protein and lipid levels and structural changes in the functional groups that comprise proteins and lipids. The study also demonstrated differences in lipid biosynthesis and protein levels in PV serum. Using the Partial Least Square Discriminant Analysis (PLS-DA) model, Raman-based multivariate analysis achieved high accuracy rates of 96.49% and 93.04% in the training sets and 93.10% and 89.66% in the test sets for the 800-1800 cm-1 and 2700-3000 cm-1 ranges, respectively. The area under the curve (AUC) values of the test datasets were calculated as 0.92 and 0.89 in the 800-1800 cm-1 and 2700-3000 cm-1 spectral regions, respectively, demonstrating the effectiveness of the PLS-DA models for the diagnosis of PV. This study highlights the potential of Raman spectroscopy-based analysis in the early and accurate diagnosis of PV, enabling the application of effective treatment strategies.

Vascular Endothelial Dysfunction in Myeloproliferative Neoplasms and Gene Mutations

Essential thrombocythemia (ET) and polycythemia vera (PV), are common Philadelphia-negative myeloproliferative neoplasms (MPN). Patients with MPN have a high rate of cardiovascular complications and often have acquired JAK2V617F and CALR genetic mutations. In this study, we aimed to analyze vascular endothelial function in patients with MPN.We evaluated 27 outpatients, including 10 patients diagnosed with MPN, flow-mediated dilatation (FMD), and nitroglycerin-mediated dilation (NMD), between September 2014 and August 2016. We measured serum adiponectin, which protects vascular endothelial function, and serum asymmetric dimethyl arginine (ADMA), which inhibits the production of adiponectin. The presence or absence of JAK2V617F and CALR mutations was evaluated in patients with MPN.Venous thrombosis was observed more frequently in patients with MPN than in those without. Seven MPN patients were diagnosed with PV, and 3 MPN patients were diagnosed with ET. JAK2V617F and CALR mutations were found in 5 and 3 MPN patients, respectively. FMD was significantly lower in JAK2V617F-positive MPN patients than in JAK2V617F-negative MPN patients, although NMD, adiponectin, and ADMA were similar in both groups. Adiponectin levels were higher and ADMA levels were lower in CALR-positive MPN patients than in CALR-negative MPN patients. There was no difference in FMD and NMD prevalence between the 2 groups. Furthermore, we had 3 representative MPN patients who were complicated with coronary spasm, possibly caused by MPN-related endothelial dysfunction.We found that patients with MPN presented with endothelial dysfunction, which was related to the presence of genetic mutations and was sometimes associated with cardiovascular disease.

Clinical characteristics of Japanese patients with polycythemia vera: results of the JSH-MPN-R18 study

The presence of a JAK2 V617F or JAK2 exon 12 mutation is one of the three major criteria listed for the diagnosis of polycythemia vera (PV) in the 2017 World Health Organization Classification. However, a nationwide study has not yet been conducted in Japan since the discovery of JAK2 mutations. Therefore, the Japanese Society of Hematology (JSH) retrospectively analyzed the clinical characteristics of 596 Japanese patients with PV diagnosed between April 2005 and March 2018. Among the 473 patients with complete data on JAK2 mutations available, 446 (94.3%) and 10 (2.1%) were positive for the JAK2 V617F and JAK2 exon 12 mutations, respectively. During a median follow-up of 46 months (range: 0-179 months), 47 (7.9%) deaths occurred. The major causes of death were secondary malignancies (23.4%), acute leukemia (12.8%), non-leukemic progressive disease (10.6%) and thrombotic (6.4%) and hemorrhagic complications (6.4%). Thrombotic and hemorrhagic events occurred during the clinical course in 4.0% (n = 24) and 3.5% (n = 21) of patients, respectively. These results show that the international PV prognostic score (age, venous thrombosis and leukocytosis) is applicable to Japanese patients with PV.

Polycythaemia Vera and Coronary Artery Bypass Graft Surgery: A Systematic Review of the Literature

OBJECTIVES

Polycythaemia vera (PV) is a condition that may potentially put patients undergoing cardiac surgery at an increased risk of bleeding and thrombosis; however, there is currently a paucity of literature regarding the management of these patients. We aim to examine the literature in this systematic review to indicate the interventions that may be considered to minimise complications.

METHODS

We conducted a literature search using keywords and MeSH terms to identify articles discussing PV and cardiac surgery. The studies were identified and qualitatively analysed using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol.

RESULTS

In total, 10 case reports representing 11 patients were identified for this systematic review and were included in qualitative analysis. 63.6% of patients had preoperative intermittent phlebotomy, and the majority of patients received postoperative therapy that involved one antiplatelet and one anticoagulant. Generous perioperative fluid management, phlebotomy, preservation of core body temperature, early extubation, monitoring of myocardial ischaemia, infarction and vascular events, intense chest physiotherapy and patient mobilisation are important to consider to reduce the risk of complications arising from surgery.

CONCLUSION

These considerations should be systematically discussed in a multidisciplinary team, where the acute surgical need can be balanced appropriately against the risk of haemorrhage and thrombosis.

Recurrent cerebral venous sinus thrombosis in a young man- A case report of JAK2-negative polycythemia vera

Polycythemia vera (PV) is a myeloproliferative disorder most commonly associated with JAK2V617F mutation. Cerebral venous sinus thrombosis (CVST) has a wide range of etiologies and PV is one of them. CVST associated with PV has a poor prognosis. Some patients with classical PV lack JAK2V617F mutation and the molecular basis of JAK2V617F-negative PV is not known. We hereby report a case of a young man who presented with headache, vomiting and altered sensorium and was found to have recurrent CSVT. The patient had primary polycythemia and was subsequently diagnosed to have JAK2-negative PV.

Testosterone Therapy: An Assessment of the Clinical Consequences of Changes in Hematocrit and Blood Flow Characteristics

INTRODUCTION

Clinical guidelines indicate that hematocrit should be monitored during testosterone replacement therapy (TTh), with action taken if a level of 0.54 is exceeded.

AIM

To consider the extent of changes in hematocrit and putative effects on viscosity, blood flow, and mortality rates after TTh.

METHODS

We focused on literature describing benefits and possible pitfalls of TTh, including increased hematocrit. We used data from the BLAST RCT to determine change in hematocrit after 30 weeks of TTh and describe a clinical case showing the need for monitoring. We consider the validity of the current hematocrit cutoff value at which TTh may be modified. Ways in which hematocrit alters blood flow in the micro- and macro-vasculature are also considered.

MAIN OUTCOME MEASURES

The following measures were assessed: (i) change in hematocrit, (ii) corresponding actions taken in clinical practice, and (iii) possible blood flow changes following change in hematocrit.

RESULTS

Analysis of data from the BLAST RCT showed a significant increase in mean hematocrit of 0.01, the increase greater in men with lower baseline values. Although 0 of 61 men given TTh breached the suggested cutoff of 0.54 after 30 weeks, a clinical case demonstrates the need to monitor hematocrit. An association between hematocrit and morbidity and mortality appears likely but not proven and may be evident only in patient subgroups. The consequences of an increased hematocrit may be mediated by alterations in blood viscosity, oxygen delivery, and flow. Their relative impact may vary in different vascular beds.

CONCLUSIONS

TTh can effect an increased hematocrit via poorly understood mechanisms and may have harmful effects on blood flow that differ in patient subgroups. At present, there appears no scientific basis for using a hematocrit of 0.54 to modify TTh; other values may be more appropriate in particular patient groups. König CS, Balabani S, Hackett GI, et al. Testosterone Therapy: An Assessment of the Clinical Consequences of Changes in Hematocrit and Blood Flow Characteristics. Sex Med Rev 2019;7:650-660.

Polycythemia Vera Presenting as Cardiac Arrest: Novel Management Strategies

Acute coronary syndromes (ACS) usually occur in patients with multiple cardiac risk factors. In young adults, drug use and hypercoagulable states are common causes for ACS presentations. We report a case of a man in his early 30s who was diagnosed with polycythemia vera (PV) and had a cardiac arrest due to an anterolateral ST elevation myocardial infarction. We discuss his unique management and review the evidence on the management of arterial thromboembolism in PV patients.

Polycythemia Vera Management and Challenges in the Community Health Setting

Patients with polycythemia vera (PV) experience shortened survival, increased risk of thromboembolic and hemorrhagic events, and burdensome symptoms. For all patients with PV, treatment with aspirin and hematocrit control with phlebotomy are recommended. In addition, patients with high-risk status or poor hematocrit control benefit from cytoreductive therapy with hydroxyurea, although approximately 1 in 4 patients develops resistance or intolerance. For patients who are resistant to or intolerant of hydroxyurea, studies have shown that ruxolitinib, a Janus kinase 1/2 inhibitor, provides hematocrit control, reduces spleen size, normalizes blood counts, and improves PV-related symptoms. For many patients, PV is managed in a community health setting, and it is important that community hematologists, oncologists, and internists are familiar with the contemporary management of PV to improve patient outcomes, including management for patients who present with unique health-care needs. This review provides an overview of current treatment options for patients with PV and discusses challenging circumstances encountered by community providers in the management of PV, including symptom assessment, identification of hydroxyurea resistance/intolerance, pregnancy, elective surgeries, concomitant immunosuppressants, and managing patients in areas with limited access to specialized hematologic care.

Abnormal adhesion of red blood cells in polycythemia vera: a prothrombotic effect?

Polycythemia vera (PV) is a myeloproliferative neoplasm (MPN) characterised by the V617F activating mutation in the tyrosine kinase JAK2. PV patients exhibit increased haemoglobin levels and red cell mass because of uncontrolled proliferation of the erythroid lineage. Thrombosis and transformation to acute leukaemia are the major causes of morbidity and mortality in this disease. Increased thrombotic risk in PV patients is multifactorial and complex; it is associated with high levels of haemoglobin, impaired rheology and increased viscosity resulting from erythrocytosis. An additional parameter that might contribute to this risk was recently brought to light by work from our group showing abnormal activation of adhesion proteins in PV RBCs. In this review we provide an overview of these recent findings and discuss how the pro-adhesive features of JAK2V617F-positive red blood cells might initiate and contribute to the circulatory complications described in PV.

Antimalarial drug artemisinin depletes erythrocytes by activating apoptotic pathways in zebrafish

Despite its extraordinary efficacy, administration of the major antimalarial drug artemisinin leads to anemia, and the underlying cellular and molecular mechanisms are not well understood. Here, we report the effects of artemisinin on erythroid development and apoptosis in zebrafish and human cells. By performing a small-molecule screen with zebrafish embryos, we found that artemisinin treatment depleted red blood cells and slightly decreased definitive hematopoietic stem cells, but had no effect on primitive hematopoietic progenitors. RNA-Seq revealed that artemisinin suppressed a cluster of genes in the heme biosynthesis and globin synthesis pathways. Furthermore, artemisinin induced apoptosis in erythrocytes in zebrafish embryos, as assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling assay, and preferentially acted on differentiated erythrocytes by elevating caspase 8 and caspase 9 activity in differentiated human K562 cells. Consistently, artemisinin suppressed the ectopic expression of erythroid genes in jak2aV581F-injected embryos, a zebrafish model for human polycythemia vera in which the bone marrow makes too many red blood cells. Taken together, our data suggested that artemisinin, in addition to killing parasites, has a direct action on differentiated erythrocytes other than definitive hematopoietic stem cells and causes erythroid apoptosis by interfering with the heme biosynthesis pathway in zebrafish and human cells.

Case studies on ESA-doping as revealed by the Biological Passport

Blood doping, through the increase of red cells, induces changes of hematological parameters. The aim of the Biological Passport is first to analyse individual longitudinal profiles in order to identify, through variations of the specific parameters, doping manipulations. Additionally, on the basis of abnormal values or profiles, athletes can be targeted for traditional anti-doping tests in order to detect forbidden substances or methods. We report the experience of the International Cycling Union in applying the Biological Passport to target athletes for the presence of erythropoiesis stimulating agents. All positive results which have been reported between 2008 and 2010 concerning athletes enrolled in the Biological Passport program are presented. Four cases are discussed more in details. To conclude, we propose possible ways of using the Biological Passport in order to better understand athletes' doping modalities, so that testing programs efficiency can be improved.

Significance of the JAK2V617F mutation in patients with chronic myeloproliferative neoplasia

In Philadelphia chromosome-negative chronic myeloproliferative neoplasia, i.e. polycythemia vera, essential thrombocythemia and primary idiopathic myelofibrosis enhanced risk of thrombosis could be connected with Janus kinase 2 gene mutation occurring in various frequency in these diseases (JAK2V617F). Since 2002 the presence of JAK2 mutation in chronic myeloproliferative neoplasia has been regularly detected. Aims: In a retrospective survey the possible connection between JAK2 mutation and thrombosis was analyzed in patients with chronic myeloproliferative neoplasia subgroups cared and treated in their hospital and outpatient departments. Patients and methods: Between 2007-2010 peripheral blood samples of 171 patients with chronic myeloproliferative neoplasia (68 patients of polycythemia vera, 84 of essential thrombocythemia and 19 ones with primary idiopathic myelofibrosis) were sent to several molecular biological laboratories, where V617F mutation from DNA specimens was detected by allele-specific polymerase chain reaction, as well. Thromboembolic complications (arterial, i.e. cerebro-and cardiovascular and venous thrombosis) occurred during course of illness of patients were registered. Statistical analysis was made by statistical software program for Windows. Results: JAK2 mutation in 53 patients with polycythemia vera (77.9%) was detected, whilst in essential thrombocythemia 55 patients (65.4%) and in primary idiopathic myelofibrosis 7 patients (36.8%) proved to be JAK2 positive. In 18 JAK2 positive patients of polycythemia vera thromboembolic episodes were observed (18/53, 33.9%), whilst in essential thrombocythemia JAK2 mutational status was accompanied with thromboembolic events in 17/55 patients (30.9%). In the 7 JAK2 positive ones with primary idiopathic myelofibrosis thrombotic complication did not occurred. However, in JAK2 negative cases thrombotic events could also be detected (from 10 JAK2 negative patients with polycythemia vera in four ones, and in six with JAK2 negative 23 essential thrombocythemic patients. Conclusions: Incidence of the JAK2 mutation in their patients with chronic myeloproliferative neoplasia subgroups mainly corresponds to the literary data. Thrombosis ensued both in JAK positive polycythemia vera and essential thrombocythemia cases occurred nearly in the same number, but the incidence of thrombosis ensued in JAK2 negative cases did not differ significantly from the JAK2 positive patients. From these results it could be suggested that the presence or absence of JAK2 mutation in the development of thrombosis has no predictive value in patients with chronic myeloproliferative neoplasia. Orv. Hetil., 2011, 152, 1795–1803.

JAK2 Negative Polycythemia Vera

Polycythemia vera (PV) is a stem cell disorder, characterized as a panhyperplastic, malignant, and neoplastic marrow disorder. Several reasons suggest that a mutation on the Janus kinase-2 gene (JAK2) is the most probable candidate gene involved in PV pathogenesis, as JAK2 is directly involved in intracellular signaling, following its exposure to cytokines, to which PV progenitor cells display hypersensitivity. A recurrent unique acquired clonal mutation in JAK2 was found in most patients with PV and other myeloproliferative diseases (MPDs). A female patient of age 50 years, presented with hemiplegia, diplopia, and had a consistent rise in hemoglobin and hematocrit. Serum Erythropoietin (Epo) was decreased. JAK2 mutation analysis was found to be negative. A diagnosis of polycythemia vera was made on the basis of the British Committee for Standards in Hematology (BCSH) guidelines.

The CYTO-PV: A Large-Scale Trial Testing the Intensity of CYTOreductive Therapy to Prevent Cardiovascular Events in Patients with Polycythemia Vera

Polycythemia vera (PV) is a chronic myeloproliferative disorder whose major morbidity and mortality are thrombohaemorragic events. Current guidelines advise maintaining hematocrit (HCT) level below 45% in males and 42% in females. Such targets lean on pathophysiological reasoning, while evidence from ECLAP and PVSG-01, the two largest prospective studies in this disease, suggests no difference in the rate of thrombosis in patients maintained at different HCT values below 50%-52%. Cytoreductive therapy in PV (CYTO-PV) is a multicenter, randomized, and controlled trial assess the benefit/risk profile of cytoreductive therapy with phlebotomy or HU aimed at maintaining HCT < 45% versus maintaining HCT in the range 45%-50%. CYTO-PV is being conducted in the framework of the Gruppo Italiano Malattie Ematologiche nell'Adulto (GIMEMA) and is funded by the Italian Drug Agency (AIFA). It is an independent trial with broad recruitment criteria to mimic clinical practice. We describe here the study and its advancement status. Conclusions. Clinical research in rare disease can be carried out with limited funds, provided a research hypothesis is felt as clinically relevant by a scientific community willing to share knowledge on the outcome of clinical practice, thus producing scientific results useful to improve treatment and prognosis of patients.

[Abnormal hemoglobins with high oxygen affinity in the differential diagnosis of polycythemia]

Hemoglobin variant with high oxygen affinity is an uncommon, often misdiagnosed, etiology of erythrocytosis. We report two cases of erythrocytosis. Their hemoglobin-oxygen dissociation curve showed a P50 value (the oxygen tension at which hemoglobin is 50% saturated) below the normal range. Globin chains electrophoresis and DNA analysis evidenced hemoglobin Olympia and hemoglobin Malmö, respectively. More than 200 variants of hemoglobin with increased oxygen affinity have been described, that are in about one-third responsible of secondary erythocytosis because of tissular hypoxia. Such abnormal haemoglobin identification should be routinely included in the diagnostic work-up of unexplained erythocytosis, particularly in young people.

Myeloproliferative disorders and the hyperviscosity syndrome

Myeloproliferative disorders and the serum hyperviscosity syndrome can rapidly manifest with emergent presentations. Hyperviscosity occurs from pathologic elevations of either the cellular or acellular (protein) fractions of the circulating blood. Classic hyperviscosity syndrome presents with the triad of bleeding diathesis, visual disturbances, and focal neurologic signs. Emergency medicine providers should be aware of these conditions and be prepared to rapidly initiate supportive and early definitive management, including plasma exchange and apharesis. Early consultation with a hematologist is essential to managing these complex patients.

Radionuclide imaging of bone marrow disorders

Noninvasive imaging techniques have been used in the past for visualization the functional activity of the bone marrow compartment. Imaging with radiolabelled compounds may allow different bone marrow disorders to be distinguished. These imaging techniques, almost all of which use radionuclide-labelled tracers, such as ^99mTc-nanocolloid, ^99mTc-sulphur colloid, ¹¹¹In-chloride, and radiolabelled white blood cells, have been used in nuclear medicine for several decades. With these techniques three separate compartments can be recognized including the reticuloendothelial system, the erythroid compartment and the myeloid compartment. Recent developments in research and the clinical use of PET tracers have made possible the analysis of additional properties such as cellular metabolism and proliferative activity, using ¹⁸F-FDG and ¹⁸F-FLT. These tracers may lead to better quantification and targeting of different cell systems in the bone marrow. In this review the imaging of different bone marrow targets with radionuclides including PET tracers in various bone marrow diseases are discussed.

Iron control of erythroid development by a novel aconitase-associated regulatory pathway

Human red cell differentiation requires the action of erythropoietin on committed progenitor cells. In iron deficiency, committed erythroid progenitors lose responsiveness to erythropoietin, resulting in hypoplastic anemia. To address the basis for iron regulation of erythropoiesis, we established primary hematopoietic cultures with transferrin saturation levels that restricted erythropoiesis but permitted granulopoiesis and megakaryopoiesis. Experiments in this system identified as a critical regulatory element the aconitases, multifunctional iron-sulfur cluster proteins that metabolize citrate to isocitrate. Iron restriction suppressed mitochondrial and cytosolic aconitase activity in erythroid but not granulocytic or megakaryocytic progenitors. An active site aconitase inhibitor, fluorocitrate, blocked erythroid differentiation in a manner similar to iron deprivation. Exogenous isocitrate abrogated the erythroid iron restriction response in vitro and reversed anemia progression in iron-deprived mice. The mechanism for aconitase regulation of erythropoiesis most probably involves both production of metabolic intermediates and modulation of erythropoietin signaling. One relevant signaling pathway appeared to involve protein kinase Calpha/beta, or possibly protein kinase Cdelta, whose activities were regulated by iron, isocitrate, and erythropoietin.

The JAK2(V617F) tyrosine kinase mutation in blood donors with upper-limit haematocrit levels

BACKGROUND

It is not rare to observe in blood donors a level of haematocrit (Hct) above or close to the highest normal limit. In the case of blood donors the diagnosis and clinical evaluation of this alteration may be complicated by regular blood donations that can mask an underlying disease such as polycythaemia vera. Recently a single acquired mutation in the Janus kinase 2 gene (JAK2) on chromosome 9 was identified and it was found that the incidence of this mutation was high in patients with polycythaemia vera.

MATERIAL AND METHODS

From the January 1, 2006 to December 31, 2006 all consecutive donors with a Hct above 50% if males (n=84) and 46% if females (n=19) underwent JAK2 mutation analysis. Seventy-nine donors (59 males and 20 females) whose Hct was normal at their last blood donation were randomly selected and used as controls.

RESULTS

Among the group of blood donors with a high Hct, we identified one donor who was positive for the JAK2 mutation. This man had a Hct of 50.6% at his last donation, while his average Hct in the preceding year was 51.7%. The prevalence of the JAK2 mutation could be estimated to be 1%, 0.6% or 0.02% in the three different populations considered: donors with a Hct level above the upper limit of normal, all tested donors or the entire donor cohort attending our transfusion service, respectively.

CONCLUSIONS

The present study suggests that apparently healthy subjects with repeatedly high levels of Hct may have the acquired mutation in JAK2. Laboratory screening tests for JAK2 may be offered to blood donors at transfusion services with expertise in molecular genetics.

Late Drug-eluting Stent Thrombosis and Erythropoietin: Cause and Effect?

A case of late thrombosis of a sirolimus-eluting stent, 16 months after implantation, is described. Two weeks prior to presentation with stent thrombosis the patient had a 50% dose increase of longterm erythropoietin. The prothrombotic effect of erythropoietin may have precipitated the thrombotic event.

Role of the activating mutation Val617Phe of Janus kinase 2 gene in myeloproliferative diseases and significance of its detection

The Val617Phe point mutation of Janus kinase 2 gene is believed to participate in the pathogenesis of myeloproliferative syndrome characterised by the clonal alteration of hematopoetic stem cells. According to current results, the frequency of Val617Phe activating mutation is around 80% in polycythaemia vera, 35% in essential thrombocythaemia, and 50% in chronic idiopathic myelofibrosis. The diagnoses of polycythaemia vera, essential thrombocythaemia and idiopathic myelofibrosis were so far based on the exclusion of secondary factors as well as bone marrow biopsy histology. The goal of the present work was to establish simple molecular genetic techniques for the routine testing of Janus kinase 2 gene Val617Phe mutation, and to compare the clinical phenotypes of Val617Phe mutation positive and negative myeloproliferative syndromes. We employed the allele specific polymerase chain technique for detection of Val617Phe mutation in 252 patients with myeloproliferative syndrome. We measured Val617Phe frequency as 85,4% (117/137) in polycytaemia vera, 56,6% (56/99) in essential thrombocythaemia, and 87,5% (14/16) in idiopathic myelofibrosis. We found significantly elevated hemoglobin levels and white blood cell counts (measured at the time of diagnosis) in Val617Phe-positive polycythaemia vera and essential thrombocythaemia patient groups compared to Val617Phe-negative patients. However, the frequencies of splenomegaly and other complications (thrombosis, bleeding, transformation to acute leukemia) were not significantly different between the mutation-positive and negative groups. In conclusion, the non-invasive mutation analysis of the Janus kinase 2 Val617Phe is suitable for routine laboratory application and helps the differential diagnosis of myeloproliferative syndrome. Althought the exact role of Val617Phe mutation testing has not yet been identified on the basis of a broad professional consensus, the testing is suggested in cases of erythrocytoses and thrombocytoses of unknown origin.

Diagnostic usefulness of the Janus kinase 2 mutation in non BCR/ABL myeloproliferative disorders

BACKGROUND

We investigated the Janus kinase 2 (JAK2) mutation and its diagnostic value in patients suffering with non BCR/ABL myeloproliferative diseases (nMPD) or other reactive conditions.

METHODS

We reviewed the clinical records of 83 patients who underwent bone marrow (BM) examinations with suspect of nMPD. The diagnoses of nMPD were made based on the WHO criteria since 2001 and the PVSG criteria before 2001. The JAK2 mutation was examined by PCR in 54 patients whose BM samples were available.

RESULTS

The JAK2 mutation was detected in 25 patients (46%); 12 of 26 patients with essential thrombocythemia (ET), 9 of 12 patients with polycyhtemia vera (PV), one of 7 patients with chronic idiopathic myelofibrosis (CIM) and one patient with unclassifiable MPD. Additionally, JAK2 mutation was detected in each one patient with secondary polycythemia and reactive thrombocytosis. These two patients and two other patients among the JAK2 mutated ET did not meet the WHO PV criteria due to their initial low hemoglobin levels. These patients had liver cirrhosis and hypersplenism due to Budd-Chiari syndrome (1), gastrointestinal bleeding (1) or the initial hemoglobin level was slightly below the level as provided by the criteria, but the level showed a rising pattern despite cytoreductive therapy (2). With the results of the JAK2 mutation available, 4 patients' disease could be re-diagnosed as PV. Finally, the positive rate of the JAK2 mutation was 81% in PV, 48% in ET and 14% in CIM. The presence of JAK2 mutation closely correlated with PV (p = 0.001), leukocytosis (0 = 0.001) and an increased cellularity of BM (p=0.024).

CONCLUSIONS

The JAK2 mutation may help differentiate nMPD from secondary cytosis. Therefore, it should be incorporated into the guidelines for the nMPD work-up for making a more accurate diagnosis and administering proper treatment.

Leukocytosis as a major thrombotic risk factor in patients with polycythemia vera

In polycythemia vera, vascular risk assessment is based on age and thrombotic history, while the role of other potential predictors of this risk is still uncertain. Thus, we exploited the large database collected by the observational study of the European Collaboration on Low-Dose Aspirin in Polycythemia Vera (ECLAP) to investigate the association of hematologic variables and cardiovascular risk factors with the thrombotic risk. Among 1638 polycythemic patients followed for 2.7 +/- 1.3 years, there were 205 thromboses. Subjects with hypertension had a mild nonsignificant increase in the risk of arterial thrombosis, while this risk was significantly increased by smoking (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.15-3.14; P = .012). The time-dependent analysis adjusted for potential confounders showed that patients with a white blood cell count above 15 x 10(9)/L, compared with those with a white blood cell count below 10 x 10(9)/L, had a significant increase in the risk of thrombosis (HR, 1.71; 95% CI, 1.10-2.65; P = .017), mainly deriving from an increased risk of myocardial infarction (HR, 2.84; 95% CI, 1.25-6.46; P = .013). Thus, leukocyte count may help in defining the vascular risk of polycythemic subjects.

Gö6976 is a potent inhibitor of the JAK 2 and FLT3 tyrosine kinases with significant activity in primary acute myeloid leukaemia cells

Aberrant activation of Janus kinase/signal transducers and activators of transcription (JAK/STAT) signalling is implicated in a number of haematological malignancies and effective JAK inhibitors may be therapeutically useful. We found that Gö6976, an indolocarbazole inhibitor of the calcium-dependent isozymes of protein kinase C (PKC), inhibited interleukin 3/granulocyte-macrophage colony-stimulating factor-induced signalling, proliferation and survival whereas Gö6983, a broad spectrum PKC inhibitor, had no such effects. Gö6976 was found to be a direct and potent inhibitor of JAK2 in vitro. Gö6976 also inhibited signalling, survival and proliferation in cells expressing the leukaemia-associated TEL-JAK2 fusion protein and the myeloproliferative disorder (MPD)-associated JAK2 V617F mutant. In primary acute myeloid leukaemia (AML) cells, incubation with Gö6976 reduced constitutive STAT activity in all cases studied. In addition, Akt and mitogen-activated protein kinase phosphorylation were reduced in 4/5 FLT3-internal tandem duplication (ITD) positive AML cases and 7/13 FLT3-wild-type (WT) cases. Expression of FLT3-WT, ITD and D835Y in 32D cells showed that Gö6976 is also a potent inhibitor of WT and mutant FLT3. In AML cells, Gö6976 reduced the survival to 55 +/- 5% of control in FLT3-ITD cases and to 69 +/- 5% in FLT3-WT samples. These data may help identify clinically useful compounds based on the structure of Gö6976, which can be employed for the treatment of MPDs as well as AML.

Essential thrombocythemia: a review of diagnostic and pathologic features

CONTEXT

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder (CMPD) characterized predominately by thrombocytosis and abnormal megakaryocyte proliferation. The current diagnostic criteria require a combination of clinical, histologic, and cytogenetic data. The diagnosis relies largely on exclusion of other causes of thrombocytosis.

OBJECTIVE

Describe historical, clinical, and laboratory features of ET in order to understand, clarify, and more accurately diagnose this entity.

DATA SOURCES

Review contemporary and historical literature on ET and other causes of thrombocytosis.

CONCLUSIONS

ET is a relatively indolent and often asymptomatic CMPD that is characterized primarily by a sustained elevation in platelets > or = 600 x 10(3)/microL (> or = 600 x 10(9)/L), proliferating enlarged and hyperlobated megakaryocytes, and minimal to absent bone marrow fibrosis. Significant changes and revisions to the diagnostic requirements and criteria for ET have occurred during the last 30 years. Recently, a mutation in the Janus kinase 2 (JAK2) gene has been found in a significant number of cases of ET and other CMPDs. In up to 57% of ET cases, a mutation in the JAK2 gene can be detected. In the absence of a JAK2 mutation and features of another CMPD, the diagnosis of ET remains a diagnosis of exclusion after other causes of thrombocytosis have been excluded.

Pleiotropic role of histone deacetylases in the regulation of human adult erythropoiesis

Histone acetylation and deacetylation play fundamental roles in transcriptional regulation. We investigated the role of histone deacetylases (HDACs) in human adult haematopoiesis, using the structurally distinct HDAC inhibitors FK228 (depsipeptide) and Trichostatin A. When CD34+ cells were cultured with interleukin (IL)-3 or stem cell factor (SCF) + IL-3, FK228 (0.5 ng/ml) specifically enhanced the generation of immature erythroid cells with a CD36+ glycophorin A (GPA)low phenotype. In semisolid cultures, FK228 promoted the formation of erythroid colonies by CD34+ cells with IL-3 and SCF + IL-3. Furthermore, upon exposure to FK228, CD34+ cell-derived CD36+ GPA- cells were induced to form erythroid colonies with IL-3 alone. Conversely, FK228 inhibited the generation of CD36+ GPAhigh relatively mature erythroid cells from CD34+ cells in the presence of erythropoietin (EPO) and SCF + EPO. FK228 suppressed the EPO-mediated survival of CD36+ GPAlow/- and CD36+ GPAhigh cells and induced their apoptosis. Similar effects were observed for trichostatin A in the generation of erythroid cells in IL-3- and EPO-containing cultures. These data suggest that HDACs negatively regulate the IL-3-mediated growth of early erythroid precursors by suppressing their responsiveness to IL-3, while playing an important role in EPO-mediated differentiation and survival of erythroid precursors. Our data revealed that HDACs have diverse functions in human adult erythropoiesis.

Proteomic approaches to dissect platelet function: Half the story

Platelets play critical roles in diverse hemostatic and pathologic disorders and are broadly implicated in various biological processes that include inflammation, wound healing, and thrombosis. Recent progress in high-throughput mRNA and protein profiling techniques has advanced our understanding of the biological functions of platelets. Platelet proteomics has been adopted to decode the complex processes that underlie platelet function by identifying novel platelet-expressed proteins, dissecting mechanisms of signal or metabolic pathways, and analyzing functional changes of the platelet proteome in normal and pathologic states. The integration of transcriptomics and proteomics, coupled with progress in bioinformatics, provides novel tools for dissecting platelet biology. In this review, we focus on current advances in platelet proteomic studies, with emphasis on the importance of parallel transcriptomic studies to optimally dissect platelet function. Applications of these global profiling approaches to investigate platelet genetic diseases and platelet-related disorders are also addressed.

Polycythemia Vera: New Clinicopathologic Perspectives

Context.—Polycythemia vera (PV) is a clonal myeloproliferative disease characterized by an erythroid dominant trilineage proliferation of hematopoietic precursor cells. Classified as a chronic myeloproliferative disease, PV represents a histopathologic spectrum of 2 recognized stages, the polycythemic and postpolycythemic phase. The clinical manifestations of hemorrhage, thrombosis, and increased red cell mass are directly related to primary bone marrow dysfunction. Prognosis is strongly associated with thrombosis risk and disease progression; thus, treatment is directed toward minimizing coagulopathic complications and preventing leukemic transformation. Recently, a specific point mutation in the Janus kinase 2 (JAK2) gene was described in a majority of PV patients. The potential diagnostic and/or prognostic value of JAK2V617F is discussed.

Objective.—To review important developments from the recent and historical literature. Modern diagnostic criteria and emerging molecular findings are emphasized.

Data Sources.—A comprehensive review was performed of the relevant literature indexed in PubMed (National Library of Medicine) and referenced medical texts.

Conclusions.—Modified clinical, histologic, and laboratory criteria have clarified the diagnosis of PV. Also, continuing studies on the recently discovered JAK2V617F gene mutation may significantly improve our understanding of PV pathogenesis and facilitate its medical management.

The role of Janus kinases in haemopoiesis and haematological malignancy

The production of blood cells is regulated by a number of protein growth factors and cytokines that influence cell survival, proliferation and differentiation. Many of these molecules bind to cell surface receptors, which belong to a family of closely related cytokine receptors that lack intrinsic catalytic activity but are intimately associated with tyrosine kinases of the Janus kinase (JAK) family. Ligand binding induces the activation of JAKs, which sit at the apex of a signalling cascade in which a key role is played by members of the signal transducers and activators of transcription (STAT) group. Congenital deficiencies in JAK-STAT signalling are associated with immunodeficiency states and acquired activating mutations and translocations are involved in the pathophysiology of haematological malignancy. The latter findings have raised hopes that drugs that target aberrant JAK-STAT signalling may be useful for the treatment of human disease.

A refined diagnostic algorithm for polycythemia vera that incorporates mutation screening for JAK2(V617F)

Historically, red cell mass (RCM) measurement has been promoted as an accurate indicator of the body's red cell content. Both the Polycythemia Vera Study Group and a committee sponsored by the World Health Organization have endorsed its inclusion in their diagnostic criteria without supporting evidence of diagnostic accuracy from a systematic study. Over the years, it has become evident that RCM measurement is a cumbersome and costly test and, as a result, it has been abandoned by many hematologists in practice. The recent discovery that a somatic JAK2-activating mutation, JAK2(V617F), is almost invariably associated with polycythemia vera further supports the use of diagnostic algorithms that are based on biologic parameters in place of traditional diagnostic criteria that are based on RCM measurement. Therefore, a contemporary approach to the diagnosis of polycythemia vera starts with peripheral blood mutation screening for JAK2(V617F) as well as measurement of serum erythropoietin. The results of these tests, along with the clinical scenario, determine the need for further investigation, including bone marrow examination.

[Mutation of protein kinase JAK2 in polycythemia vera: new perspectives in physiopathology and therapy]

INTRODUCTION

The pathogenic mechanisms of polyvythemia vera (PV) still remain unknown, although there is evidence that genetic parameters may play a role in the pathogenesis of the disease.

EXEGESIS

In 2005, many international research groups have identified an acquired mutation in the Janus kinase (JAK2) gene of chromosome 9; the mutation is defined by a valine-to-phenylalanine substitution at amino acid position 617 (V617F) in the JAK2's pseudokinase domain. JAK2 V617F mutation has been found in as high as 65 to 97% of patients with PV. Both in vitro and in vivo functional studies have further indicated that JAK2 V617F mutation leads to dysregulation of kinase activity, explaining, in part, clinical and biochemical features of PV.

CONCLUSION

These data suggest that JAK2 V617F mutation may be a novel diagnostic marker of PV. Moreover, JAK2 V617F mutation finding may permit promising therapeutic approaches in patients with PV, particularly tyrosine kinase inhibitors; preliminary series have, in fact, underscored the potential efficacy of imatinib mesylate in PV.

Mutation screening for JAK2V617F: when to order the test and how to interpret the results

With the application of adequately sensitive tests, it is now becoming evident that more than 90% of patients with conventionally-defined polycythemia vera (PV) carry the somatic JAK2V617F mutation in their granulocytes. However, the specific mutation is also found in other classic and atypical myeloproliferative disorders (MPD), albeit at a lesser frequency. In contrast, JAK2V617F has not been reported in patients with either reactive myeloproliferation or lymphoid disorders. Therefore, mutation screening for JAK2V617F can be considered as a myeloid-specific clonality assay and it is diagnostically most useful in the evaluation of "polycythemia".