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.

JAK2-V617F is a negative regulation factor of SHIP1 protein and thus influences the AKT signaling pathway in patients with Myeloproliferative Neoplasm (MPN)

BACKGROUND

Myeloproliferative neoplasms (MPN) are a group of chronic haematological disorders. At the molecular level of MPN cells, the gain-of-function mutation V617F of the Janus kinase 2 (JAK2) leads to a constitutive activation of the downstream signaling cascade and is a conventional criteria for diagnosis. Here, the functional role of the tumor suppressor SHIP1 (SH2 domain containing inositol-5 phosphatase 1) in the pathogenesis of MPNs was investigated.

METHODS

Primary blood samples of MPN-patients were analysed using Western Blot technique regarding the level of SHIP1 expression. Moreover, SHIP1 and SHIP1-mutations were lentivirally transduced in the JAK2-V617F-positive UKE-1 cell line and expression was monitored over time. In addition, we examined SHIP1 reconstitution by inhibition of JAK2-V617F. Furthermore, we transfected SHIP1-expressing cells with a JAK2-V617F respectively a BCR-ABL construct and investigated changes in SHIP1 expression.

RESULTS

Four out of five MPN-patient samples showed a loss or a reduction in SHIP1 expression. We identified JAK2 as a negative regulator of SHIP1 expression in MPN cells and inhibition of JAK2-V617F implicates a reconstituted SHIP1 expression. This is significant because SHIP1 negatively regulates the AKT signaling pathway and in consequence the reconstitution of SHIP1 expression leads to a decreased cell growth. Moreover, we examined the impact of SHIP1 and patient-derived SHIP1-mutations on AKT phosphorylation and show the benefit of a combined therapy in MPN cells with inhibitors of the AKT/mTOR pathway.

CONCLUSION

In summary, the data suggest that SHIP1 may play a role during the development of MPNs and could be the basis for establishing a targeted therapy.

Management of Myeloproliferative Neoplasms (MPNs)

PURPOSE

To provide up to date guidance, practice recommendations and highlight barriers to medication adherence in the long-term management of chronic myeloproliferative neoplasms (MPNs).

AIM

Current drug therapy for MPN is not curative and has not been shown to prolong survival. The main indication for treatment is the prevention of thrombosis and medication adherence remains a challenge in this group of patients. Identifying potentially modifiable barriers to medication adherence including primary nonadherence and non-persistent adherence enables timely interventions to be put in place and improve overall medication adherence.

METHODS

A systematic review of peer-reviewed literature and expert opinions was performed using electronic databases (PubMed, EMBASE, MEDLINE, and Web of Science) that were searched for articles reporting MPN and medication adherence. Discussions A case vignette is discussed throughout the article and expert opinion with international peer reviewed guidelines that are authored to support clinical decision making at the point of care were utilised. The evidence base was combined with more practical/clinical (data based) insight from real world clinical practice. Adoption of a broad range of digital health care activities and services in the health care system (telehealth applications) by the advanced practice providers (Non-Medical Prescribers-NMPs) in MPN clinics included medication prescribing and management, oral drug compliance and adherence evaluations, interventions, chronic care management, counselling and patient education on treatments.

CONCLUSION

Current drug therapy for MPN is neither curative nor has it been shown to prolong survival, and medication adherence remains a challenge in this group of patients. The longevity of the patients' disease course may contribute to the high risk of non-adherence in this patient cohort. Poor adherence to long-term therapies severely compromises the effectiveness of treatment. Adherence interventions should be tailored to the needs of the patient in order to achieve maximum impact. Interventions aimed at improving adherence provide the best experience and outcome for the patient and their families and can have a profound impact on the quality of life and mitigation of disease consequences.

Role of inflammation in the biology of myeloproliferative neoplasms

What is the role of inflammation in Myeloproliferative Neoplasms? This is currently a topic of much debate. In this review, we will discuss experimental results and basic concepts of inflammatory processes in the pathogenesis of myeloproliferative neoplasms (MPN). So, which are the players involved? First, these are the clonal hematopoietic stem cells (HSC) and their normal stem cell counterparts in the bone marrow (BM), as well as their more mature progeny in the BM and the peripheral blood (PB), including neutrophils, macrophages, erythrocytes, and platelets, but also other cell lineages. Second, these cells produce a plethora of inflammatory cytokines, such as interleukin 6 (IL6), interleukin 8 (IL8), TNF-alpha (TNFa), interferon-alpha (IFNa), and others. Third, these cells and cytokines act in concert with non-hematopoietic cells, including endothelial cells and mesenchymal stromal cells (MSCs). The latter cells, in particular GLI1 positive or leptin receptor (LepR) positive stromal cells, may become activated by the hematopoietic clone to give rise to myofibroblasts, producing excessive fibrosis in the bone marrow (myelofibrosis). Ultimately, the inflammatory and fibrotic circuit involving these three key players may lead to progression of the disease, resulting in BM failure and transformation into acute leukemia, also termed blast crisis. Here, we review the role of these three effectors in the pathogenesis of MPN.

Role of inflammation in the biology of myeloproliferative neoplasms

What is the role of inflammation in Myeloproliferative Neoplasms? This is currently a topic of much debate. In this review, we will discuss experimental results and basic concepts of inflammatory processes in the pathogenesis of myeloproliferative neoplasms (MPN). So, which are the players involved? First, these are the clonal hematopoietic stem cells (HSC) and their normal stem cell counterparts in the bone marrow (BM), as well as their more mature progeny in the BM and the peripheral blood (PB), including neutrophils, macrophages, erythrocytes, and platelets, but also other cell lineages. Second, these cells produce a plethora of inflammatory cytokines, such as interleukin 6 (IL6), interleukin 8 (IL8), TNF-alpha (TNFa), interferon-alpha (IFNa), and others. Third, these cells and cytokines act in concert with non-hematopoietic cells, including endothelial cells and mesenchymal stromal cells (MSCs). The latter cells, in particular GLI1 positive or leptin receptor (LepR) positive stromal cells, may become activated by the hematopoietic clone to give rise to myofibroblasts, producing excessive fibrosis in the bone marrow (myelofibrosis). Ultimately, the inflammatory and fibrotic circuit involving these three key players may lead to progression of the disease, resulting in BM failure and transformation into acute leukemia, also termed blast crisis. Here, we review the role of these three effectors in the pathogenesis of MPN.

Janus Kinase V617F Mutation Detection in Patients with Myelofibrosis

Myelofibrosis (MF) is characterized by a presence of an extra fibrous tissue in the bone marrow and additional hematopoiesis. The somatic mutation in the Janus kinase 2 (JAK2) gene (V617F) occurs gradually and is detected in about 50.0% of myelofibrosis or essential thrombo-cytopenia (ET) patients. Our aim was to determine the genotype status according to the carriers of the V617F mutation in patients with MF at the Hematology Ward of the University Hospital "Ivan Rilski" in Sofia, Bulgaria. DNA samples were isolated from venous blood of patients with various hematological disorders. DNA was amplified by polymerase chain reaction (PCR) and subsequent restriction analysis was performed using a BsaXI restriction enzyme. The genotype status was determined on 2.0% agarose gel. We analyzed 38 patients initially suspected of carrying MF or osteomyelofibrosis (OMF). After trepanobiopsy, 20 out of 38 patients were confirmed as myelofibrotic (52.6%), 5/38 (13.2%) were diagnosed as ET, 1/38 (2.6%) was diagnosed as myeloproliferative neoplasm (MPN), 6/38 (15.8%) had polycythemia vera (PV). In six patients, the presence of disease was rejected. Patients with MF were divided into three groups according to the JAK2 V617F genotype status: homozygous for the mutation (3/20 or 15.0%), heterozygous (9/20 or 45.0%) and homozygous for the wild type allele (8/20 or 40.0%). The triggering factor of MF is still unknown. It was considered that this factor could have a genetic nature. Mutations in three genes were mainly accepted as an actual predisposing events to this disease: point mutations leading to amino acid substitutions in JAK2 (V617F) and in MPL (W515L, W515K), as well as insertion or deletion in CALK We have proven that carriers of the V617F mutation prevailed in the group of patients with MF (altogether 12 patients or 60.0%). Previous studies also showed that JAK2 V617F is present in more than half of MF patients within their blood-forming cells. Therefore, the risk of evolution to MF could be associated with V617F-mutant allele burden in patients with MPN.

Novel Detection of CALR-Mutated Cells in Myeloproliferative Neoplasm-Related Glomerulopathy With Interstitial Extramedullary Hematopoiesis: A Case Report

Myeloproliferative neoplasms (MPNs) are associated with somatic mutations of genes including JAK2, CALR, or MPL in hematopoietic stem cells. Various glomerular lesions are known to be involved in MPN-related glomerulopathy, including mesangial hypercellularity, segmental sclerosis, features of chronic thrombotic microangiopathy, and intracapillary hematopoietic cell infiltration. Renal extramedullary hematopoiesis (EMH) is uncommon, but it is reported to occur in the setting of MPN; however, to our knowledge, there have been no reports of renal EMH with pathologically verified mutations. We report the case of a 65-year-old woman with MPN who had a CALR mutation and developed nephrotic syndrome. Kidney biopsy showed the typical findings of MPN-related glomerulopathy. CALR mutation-specific immunostaining of the kidney revealed immunopositive cells in the EMH lesion of the interstitium, indicating that renal EMH was caused by CALR-mutated cells. Based on these findings, we diagnosed nephrotic syndrome caused by MPN-related glomerulopathy. After initiation of steroid therapy, the patient's proteinuria gradually decreased and she achieved an incomplete remission. Additionally, the patient was prescribed the JAK inhibitor ruxolitinib and maintained incomplete remission. There is no established treatment for MPN-related glomerulopathy; therefore, further studies are needed to elucidate its pathophysiology.

Health care setting and severity, symptom burden, and complications in patients with Philadelphia-negative myeloproliferative neoplasms (MPN): a comparison between university hospitals, community hospitals, and office-based physicians

Philadelphia-negative myeloproliferative neoplasms (MPN) comprise a heterogeneous group of chronic hematological malignancies with significant variations in clinical characteristics. Due to the long survival and the feasibility of oral or subcutaneous therapy, these patients are frequently treated outside of larger academic centers. This analysis was performed to elucidate differences in MPN patients in three different health care settings: university hospitals (UH), community hospitals (CH), and office-based physicians (OBP). The MPN registry of the Study Alliance Leukemia is a non-interventional prospective study including adult patients with an MPN according to WHO criteria (2008). For statistical analysis, descriptive methods and tests for significant differences were used. Besides a different distribution of MPN subtypes between the settings, patients contributed by UH showed an impaired medical condition, a higher comorbidity burden, and more vascular complications. In the risk group analyses, the majority of polycythemia vera (PV) and essential thrombocythemia (ET) patients from UH were classified into the high-risk category due to previous vascular events, while for PV and ET patients in the CH and OBP settings, age was the major parameter for a high-risk categorization. Regarding MPN-directed therapy, PV patients from the UH setting were more likely to receive ruxolitinib within the framework of a clinical trial. In summary, the characteristics and management of patients differed significantly between the three health care settings with a higher burden of vascular events and comorbidities in patients contributed by UH. These differences need to be taken into account for further analyses and design of clinical trials.

Tyrosine 625 plays a key role and cooperates with tyrosine 630 in MPL W515L-induced signaling and myeloproliferative neoplasms

BACKGROUND

Myeloproliferative neoplasms (MPN) are a group of blood cancers that boost normal blood cell production in the bone marrow. Abnormal mutations in stem cells were found accompanying with the occurrence of MPN. It has been shown that MPL mutations (MPL W515L or MPL W515K) were involved in patients with MPN. Since tyrosine residues 625 and 630 mediate normal MPL signaling, whether them affect MPL W515L-induced myeloproliferative neoplasms (MPNs) is unknown.

RESULTS

In this study, we further tested their functions in MPL W515L-induced myeloproliferative neoplasms (MPNs) by substituting either or both of them with phenylalanine in MPL W515L (termed as MPL515/625, MPL515/630 and MPL515/625/630, respectively). In vitro, MPL515/630 but not MPL515/625 or MPL515/625/630 retained the ability to induce TPO-independent proliferation and increase colony-forming unit megakaryocytes (CFU-Mk). Accordingly, differential activation of the downstream signaling by four mutants was observed and constitutively active STAT5 or AKT instead of STAT3 partially compensated MPL515/625/630 function. Further support this, STAT5-deficiency impaired MPL W515L-induced CFU-Mk expansion. In vivo, MPL515/630 but not MPL515/625 or MPL515/625/630 induced typical features of MPNs with high WBC and platelet counts, splenomegaly, hepatomegaly and hypercellularity in the bone marrow. Surprisingly, MPL515/625 also caused hypercellularity of bone marrow and splenomegaly without any other significant features. We also observed differential effects of the four mutants on progenitors, myeloid cells and megakaryocytes.

CONCLUSIONS

Our studies have revealed distinct features of tyrosine sites 625 and 630 in mediating MPL W515L-induced megakaryocyte hyperproliferation and MPNs. Our study also suggests that MPL cytosolic phosphorylated Y625 and flanking amino acids could become targets for pharmacologic inhibition in MPNs.

Role of hematopoietic stem cell transplantation in patients with myeloproliferative disease

Myeloproliferative neoplasms (MPN) are clonal hematopoietic stem cell disorders. While some MPN patients have an indolent course, all are at risk of progressing to severe marrow failure or transforming into acute leukemia. Allogeneic hematopoietic cell transplantation (allo-HCT) is the only potential curative therapy. Major pre-transplant risk factors are disease stage of the MPN, the presence of comorbid conditions and the use of HLA non-identical donors. The development of reduced-intensity conditioning regimens has allowed for successful allo-HCT even for older patients and patients with comorbid conditions. The pre-transplant use of JAK2 inhibitors, which may be effective in down staging a patient's disease, may improve the outcomes following allo-HCT.