Thromboinflammation in Myeloproliferative Neoplasms (MPN)-A Puzzle Still to Be Solved

Myeloproliferative Neoplasms and Dementia Risk: A Population-Based Cohort Study

Objectives

To estimate dementia risk for persons diagnosed with Philadelphia chromosome–negative myeloproliferative neoplasms (MPNs), which serve as a human chronic inflammation model.

Methods

We identified 9895 individuals in Denmark newly diagnosed with MPNs from 1995 to 2017; matched them 10:1 by age and sex with a general population cohort of 95 770 individuals; and followed them until dementia identification, death, emigration, or December 31, 2018. We applied a Cox proportional‐hazards regression model to estimate the cause‐specific hazard ratios (HRs) and 95% confidence intervals (CIs) for dementia. We included control diseases, like chronic lymphocytic leukemia (CLL), which is not characterized by chronic inflammation.

Results

Patients with MPNs showed a 1.15‐fold (95% CI: 1.04–1.27) increased incidence of dementia compared with members of the general population. Associations were stronger for men with MPNs (HR: 1.40, 95% CI: 1.19–1.63) than for women (HR: 1.02, 95% CI: 0.89–1.15). Patients with CLL showed a decreased dementia incidence (HR: 0.81, 95% CI: 0.72–0.90). The findings for CLL could be explained by depletion‐of‐susceptibles bias, suggesting that the findings for MPNs were underestimated by a similar bias.

Conclusions

The findings support MPNs as risk factors for dementia and the role of chronic inflammation in dementia development.

Secondary Solid Cancers in Patients with Philadelphia Chromosome-Negative Myeloproliferative Neoplasms: A Multicenter Study

Objective

We investigated the occurrence and characteristics of secondary solid cancers (SSCs) in patients with Philadelphia chromosome-negative myeloproliferative neoplasms (Ph- MPNs) from Türkiye. We identified the potential risk factors for SSC development, including the impact of cytoreductive therapies, and we assessed the influence of SSC on patient survival.

Materials and Methods

A total of 1013 Ph- MPN patients diagnosed between 1995 and 2022 were retrospectively analyzed. Data related to demographics, clinical and laboratory parameters, SSC development, cytoreductive therapy exposure, and survival outcomes were collected. Statistical analyses were performed using IBM SPSS Statistics 26.0.

Results

Of the analyzed Ph- MPN patients, 6.6% developed SSC, with carcinoma being the most common type. Older age at the time of Ph- MPN diagnosis and male sex were associated with SSC occurrence. Ph- MPN patients diagnosed with SSC and patients with no diagnosis of SSC showed no significant difference in complete blood count results, spleen size, Ph- MPN diagnostic groups, or driver mutation frequencies. However, patients with SSC had a higher frequency of arterial thrombosis and a tendency towards an increased rate of total thrombosis (p=0.030 and p=0.069, respectively). In multivariate analysis, arterial thrombosis was the sole independent risk factor and interferon (IFN)-based therapy was the sole protective factor for SSC development. Median overall survival (OS) did not differ between patients with and without SSC except for polycythemia vera patients with SSC, who had shorter OS (175±15 versus 321±26 months, respectively; p=0.005).

Conclusion

This study highlights the prevalence and characteristics of SSCs in Turkish patients diagnosed with Ph- MPNs. Arterial thrombosis was associated with increased SSC risk while IFN-based therapy offered potential protection from SSC. Screening for SSC in Ph- MPN patients with arterial thrombosis may be valuable. These findings emphasize the importance of malignancy screening in Ph- MPN patients, especially in high-risk subgroups, and call for further research to elucidate the underlying mechanisms and optimize treatment strategies.

Impact of Phlebotomy on Quality of Life in Low-Risk Polycythemia Vera

Polycythemia vera is an indolent myeloproliferative disorder that predisposes patients to venous and arterial thrombosis and can transform into myelofibrosis and acute myeloid leukemia. Consistent phlebotomy prevents life-threatening cerebrovascular and coronary artery disease and prolongs survival in low-risk polycythemia vera (patients under 60 years without thrombosis). However, despite its effectiveness in preventing serious complications, phlebotomy does not necessarily enhance the quality of life (QoL). This review assesses QoL issues associated with low-risk PV, explores alternative management strategies such as erythrocytapheresis, and discusses the roles of hydroxyurea, peginterferon, ruxolitinib, and other novel agents in potentially improving disease management and patient outcomes.

Increased mRNA expression for serotonin receptor 1B (HTR1B) is associated with thrombosis in BCR::ABL1-negative myeloproliferative neoplasms

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are clonal haematopoietic stem cell disorders characterized by specific driver mutations and an increased risk of both macrothrombosis and microthrombosis. Serotonin receptor type 1B (HTR1B) was found to be expressed by various solid tumours, and also primary bone marrow mononuclear cells from myelodysplastic neoplasm and acute myeloid leukaemia patients, representing a potential therapeutic target. In this study we assessed for the first time the expression levels of HTR1B mRNA in the peripheral blood mononuclear cells (PBMC) of 85 newly diagnosed MPN patients, consisting of 28 polycythemia vera, 25 essential thrombocythemia and 32 primary myelofibrosis cases. Levels of HTR1B expression between MPN subtypes and control group were not significantly different. However, at clinical data examination, it was observed that MPN patients with a recent history of major thrombosis and/or signs of impaired microcirculation exhibited significantly higher HTR1B expression levels compared to non-thrombotic MPNs and control group. Moreover, thrombotic MPN patients had significantly higher HTR1B expression than patients with recent thrombosis and absence of MPN diagnostic criteria. These findings suggest that increased levels of HTR1B expression in PBMC might be associated with thrombosis in MPN patients, but larger studies are needed for confirmation, including testing of the receptor protein expression level.

Structural, Biochemical Characterization and Molecular Mechanism of Cerastokunin: A New Kunitz-Type Peptide with Potential Inhibition of Thrombin, Factor Xa and Platelets

The current investigation focused on separating Cerastes cerastes venom to produce the first Kunitz-type peptide. Based on its anti-trypsin effect, Cerastokunin, a 7.75 kDa peptide, was purified until homogenity by three steps of chromatography. Cerastokunin was found to include 67 amino acid residues that were obtained by de novo sequencing using LC-MALDI-MSMS. Upon alignment with Kunitz-type peptides, there was a high degree of similarity. Cerastokunin's 3D structure had 12% α-helices and 21% β-strands with pI 8.48. Cerastokunin showed a potent anticoagulant effect by inhibiting the protease activity of thrombin and trypsin as well as blocking the intrinsic and extrinsic coagulation pathways. In both PT and aPPT, Cerastokunin increased the blood clotting time in a dose-dependent way. Using Lys48 and Gln192 for direct binding, Cerastokunin inhibited thrombin, Factor Xa and trypsin as shown by molecular docking. Cerastokunin exhibited a dose-response blockade of PARs-dependent pathway platelet once stimulated by thrombin. An increased concentration of Cerastokunin resulted in a larger decrease of tail thrombus in the mice-carrageenan model in an in vivo investigation when compared to the effects of antithrombotic medications. At all Cerastokunin doses up to 6 mg/kg, no in vivo toxicity was seen in challenged mice over the trial's duration.

Neutrophil-specific expression of JAK2-V617F or CALRmut induces distinct inflammatory profiles in myeloproliferative neoplasia

BACKGROUND

Neutrophils play a crucial role in inflammation and in the increased thrombotic risk in myeloproliferative neoplasms (MPNs). We have investigated how neutrophil-specific expression of JAK2-V617F or CALRdel re-programs the functions of neutrophils.

METHODS

Ly6G-Cre JAK2-V617F and Ly6G-Cre CALRdel mice were generated. MPN parameters as blood counts, splenomegaly and bone marrow histology were compared to wild-type mice. Megakaryocyte differentiation was investigated using lineage-negative bone marrow cells upon in vitro incubation with TPO/IL-1β. Cytokine concentrations in serum of mice were determined by Mouse Cytokine Array. IL-1α expression in various hematopoietic cell populations was determined by intracellular FACS analysis. RNA-seq to analyse gene expression of inflammatory cytokines was performed in isolated neutrophils from JAK2-V617F and CALR-mutated mice and patients. Bioenergetics of neutrophils were recorded on a Seahorse extracellular flux analyzer. Cell motility of neutrophils was monitored in vitro (time lapse microscopy), and in vivo (two-photon microscopy) upon creating an inflammatory environment. Cell adhesion to integrins, E-selectin and P-selection was investigated in-vitro. Statistical analysis was carried out using GraphPad Prism. Data are shown as mean ± SEM. Unpaired, two-tailed t-tests were applied.

RESULTS

Strikingly, neutrophil-specific expression of JAK2-V617F, but not CALRdel, was sufficient to induce pro-inflammatory cytokines including IL-1 in serum of mice. RNA-seq analysis in neutrophils from JAK2-V617F mice and patients revealed a distinct inflammatory chemokine signature which was not expressed in CALR-mutant neutrophils. In addition, IL-1 response genes were significantly enriched in neutrophils of JAK2-V617F patients as compared to CALR-mutant patients. Thus, JAK2-V617F positive neutrophils, but not CALR-mutant neutrophils, are pathogenic drivers of inflammation in MPN. In line with this, expression of JAK2-V617F or CALRdel elicited a significant difference in the metabolic phenotype of neutrophils, suggesting a stronger inflammatory activity of JAK2-V617F cells. Furthermore, JAK2-V617F, but not CALRdel, induced a VLA4 integrin-mediated adhesive phenotype in neutrophils. This resulted in reduced neutrophil migration in vitro and in an inflamed vessel. This mechanism may contribute to the increased thrombotic risk of JAK2-V617F patients compared to CALR-mutant individuals.

CONCLUSIONS

Taken together, our findings highlight genotype-specific differences in MPN-neutrophils that have implications for the differential pathophysiology of JAK2-V617F versus CALR-mutant disease.

The role of leukocytes in myeloproliferative neoplasm thromboinflammation

Classic myeloproliferative neoplasms lacking the Philadelphia chromosome are stem cell disorders characterized by the proliferation of myeloid cells in the bone marrow and increased counts of peripheral blood cells. The occurrence of thrombotic events is a common complication in myeloproliferative neoplasms. The heightened levels of cytokines play a substantial role in the morbidity and mortality of these patients, establishing a persistent proinflammatory condition that culminates in thrombosis. The etiology of thrombosis remains intricate and multifaceted, involving blood cells and endothelial dysfunction, the inflammatory state, and the coagulation cascade, leading to hypercoagulability. Leukocytes play a pivotal role in the thromboinflammatory process of myeloproliferative neoplasms by releasing various proinflammatory and prothrombotic factors as well as interacting with other cells, which contributes to the amplification of the clotting cascade and subsequent thrombosis. The correlation between increased leukocyte counts and thrombotic risk has been established. However, there is a need for an accurate biomarker to assess leukocyte activation. Lastly, tailored treatments to address the thrombotic risk in myeloproliferative neoplasms are needed. Therefore, this review aims to summarize the potential mechanisms of leukocyte involvement in myeloproliferative neoplasm thromboinflammation, propose potential biomarkers for leukocyte activation, and discuss promising treatment options for controlling myeloproliferative neoplasm thromboinflammation.

Features of immune mediated diseases in JAK2 (V617F)-positive myeloproliferative neoplasms and the potential therapeutic role of JAK inhibitors

OBJECTIVE

The Janus Kinase (JAK) 2 (V617F) mutation is the most frequently detected in myeloproliferative neoplasms (MPN). JAK2(V617F) mutation displays a pro-inflammatory phenotype that may be associated to a higher risk of immune mediated diseases (IMIDs), thromboembolic complications or other cancers. We aimed to evaluate the prevalence and main features of both rheumatic and non-rheumatic IMIDs in a cohort of MPNs patients with JAK2 (V617F) mutation.

METHODS

Study of all patients diagnosed with MPNs and JAK2 (V617F) mutation at a tertiary hospital in Northern Spain from 2004 to 2022. We focused on patients with rheumatic IMIDs to assess the time from IMIDs diagnosis to the detection of JAK2V617F mutation, the clinical course and severity of the disease, potential thrombotic complications, malignancies and therapeutic response.

RESULTS

130 patients (73 men/57 women; mean age, 70.1 ± 14.5 years) were identified. Fifty-four (41.5 %) patients were diagnosed with at least one IMID. The prevalence of rheumatic IMIDs was 7.7 % (n = 10), including rheumatoid arthritis (n = 4), polymyalgia rheumatica (n = 3), Sjögren syndrome (n = 1), antiphospholipid syndrome (n = 1) and autoinflammatory syndrome with WDR1 mutation (n = 1). Thrombotic complications were observed in 4 of these 10 patients. The clinical course of the rheumatic IMID was mild in most cases and responded to conventional immunosuppressive therapy. One patient was successfully treated with Baricitinib, a JAK1/JAK2 inhibitor.

CONCLUSIONS

A high prevalence of rheumatic IMIDs is observed in patients with MPNs and JAK2 (V617F) mutation. JAK inhibitors might be a targeted therapy option in these patients.

Activating mutations in JAK2 and CALR differentially affect intracellular calcium flux in store operated calcium entry

BACKGROUND

Calcium (Ca2+) signaling regulates various vital cellular functions, including integrin activation and cell migration. Store-operated calcium entry (SOCE) via calcium release-activated calcium (CRAC) channels represents a major pathway for Ca2+ influx from the extracellular space in multiple cell types. The impact of JAK2-V617F and CALR mutations which are disease initiating in myeloproliferative neoplasms (MPN) on SOCE, calcium flux from the endoplasmic reticulum (ER) to the cytosol, and related key signaling pathways in the presence or absence of erythropoietin (EPO) or thrombopoietin (TPO) is poorly understood. Thus, this study aimed to elucidate the effects of these mutations on the aforementioned calcium dynamics, in cellular models of MPN.

METHODS

Intracellular Ca2+ levels were measured over a time frame of 0-1080 s in Fura-2 AM labeled myeloid progenitor 32D cells expressing various mutations (JAK2-WT/EpoR, JAK2-V617F/EpoR; CALR-WT/MPL, CALR-ins5/MPL, and del52/MPL). Basal Ca2+ concentrations were assessed from 0-108 s. Subsequently, cells were stimulated with EPO/TPO in Ca2+-free Ringer solution, measuring Ca2+ levels from 109-594 s (store depletion). Then, 2 mM of Ca2+ buffer resembling physiological concentrations was added to induce SOCE, and Ca2+ levels were measured from 595-1080 s. Fura-2 AM emission ratios (F340/380) were used to quantify the integrated Ca2+ signal. Statistical significance was assessed by unpaired Student's t-test or Mann-Whitney-U-test, one-way or two-way ANOVA followed by Tukey's multiple comparison test.

RESULTS

Following EPO stimulation, the area under the curve (AUC) representing SOCE significantly increased in 32D-JAK2-V617F cells compared to JAK2-WT cells. In TPO-stimulated CALR cells, we observed elevated Ca2+ levels during store depletion and SOCE in CALR-WT cells compared to CALR-ins5 and del52 cells. Notably, upon stimulation, key components of the Ca2+ signaling pathways, including PLCγ-1 and IP3R, were differentially affected in these cell lines. Hyper-activated PLCγ-1 and IP3R were observed in JAK2-V617F but not in CALR mutated cells. Inhibition of calcium regulatory mechanisms suppressed cellular growth and induced apoptosis in JAK2-V617F cells.

CONCLUSIONS

This report highlights the impact of JAK2 and CALR mutations on Ca2+ flux (store depletion and SOCE) in response to stimulation with EPO and TPO. The study shows that the JAK2-V617F mutation strongly alters the regulatory mechanism of EpoR/JAK2-dependent intracellular calcium balance, affecting baseline calcium levels, EPO-induced calcium entry, and PLCγ-1 signaling pathways. Our results reveal an important role of calcium flux in the homeostasis of JAK2-V617F positive cells.

Inflammation as a cause of acute myocardial infarction in patients with myeloproliferative neoplasm

Myeloproliferative neoplasms (MPN) are a group of diseases characterized by the clonal proliferation of hematopoietic progenitor or stem cells. They are clinically classifiable into four main diseases: chronic myeloid leukemia, essential thrombocythemia, polycythemia vera, and primary myelofibrosis. These pathologies are closely related to cardio- and cerebrovascular diseases due to the increased risk of arterial thrombosis, the most common underlying cause of acute myocardial infarction. Recent evidence shows that the classical Virchow triad (hypercoagulability, blood stasis, endothelial injury) might offer an explanation for such association. Indeed, patients with MPN might have a higher number and more reactive circulating platelets and leukocytes, a tendency toward blood stasis because of a high number of circulating red blood cells, endothelial injury or overactivation as a consequence of sustained inflammation caused by the neoplastic clonal cell. These abnormal cancer cells, especially when associated with the JAK2V617F mutation, tend to proliferate and secrete several inflammatory cytokines. This sustains a pro-inflammatory state throughout the body. The direct consequence is the induction of a pro-thrombotic state that acts as a determinant in favoring both venous and arterial thrombus formation. Clinically, MPN patients need to be carefully evaluated to be treated not only with cytoreductive treatments but also with cardiovascular protective strategies.

Acute myocardial infarction in myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of hematologic malignancies characterized by an abnormal proliferation of cells of the myeloid lineage. Affected individuals are at increased risk for cardiovascular and thrombotic events. Myocardial infarction (MI) may be one of the earliest clinical manifestations of MPNs or may be a thrombotic complication that develops during the natural course of the disease. In the present review, we examine the epidemiology, pathogenesis, clinical presentation, and management of MI in MPNs based on the available literature. Moreover, we review potential biomarkers that could mediate the MI-MPNs crosstalk, from classical biochemical tests, e.g., lactate dehydrogenase, creatine kinase and troponins, to pro-inflammatory cytokines, oxidative stress markers, and clonal hematopoiesis.

Primary Arterial Hypertension and Drug-Induced Hypertension in Philadelphia-Negative Classical Myeloproliferative Neoplasms: A Systematic Review

The impact of primary arterial hypertension (HTN) in myeloproliferative neoplasms (MPNs) remains unclear, with scant literature available, mostly focusing on cardiovascular risk factors as a singular entity or on organ-specific HTN. Furthermore, available studies reporting findings on drug-induced HTN in MPNs report varying and contradictory findings. In consideration of the above, this study set out to systematically review the available literature and shed light on the occurrence of HTN in MPNs, its association with thrombosis, as well as the drugs used in MPN management that could increase blood pressure. The literature search yielded 598 potentially relevant records of which 315 remained after the duplicates (n = 283) were removed. After we screened the titles and the abstracts of these publications, we removed irrelevant papers (n = 228) and evaluated the full texts of 87 papers. Furthermore, 13 records did not meet the inclusion criteria and were excluded from the systematic review. Finally, a total of 74 manuscripts were entered into the qualitative synthesis and included in the present systematic review. Our systematic review highlights that HTN is the most common comorbidity encountered in MPNs, with an impact on both the occurrence of thrombosis and survival. Moreover, drug-induced HTN remains a challenge in the management of MPNs. Further research should investigate the characteristics of patients with MPNs and HTN, as well as clarify the contribution of HTN to the development of thrombotic complications, survival and management in MPNs. In addition, the relationship between clonal hematopoiesis of indeterminate potential, HTN, cardiovascular disease and MPNs requires examination in upcoming assessments.

Pediatric Philadelphia-Negative Myeloproliferative Neoplasms in the Era of WHO Classification: A Systematic Review

BACKGROUND

Philadelphia-negative myeloproliferative neoplasms (MPN) are most prevalent in the older population (median age at the diagnosis is above 60 years) and rarely diagnosed in pediatrics. Thus, our knowledge about the clinical presentation, mutational status, and complications of MPNs in pediatrics is limited.

METHODS

The literature in English (PubMed, SCOPUS, and Google Scholar) was searched for studies, reviews, case series, and case reports of patients with Philadelphia-negative MPNs (including essential thrombocythemia, polycythemia vera, primary myelofibrosis, and profibrotic myelofibrosis) in the pediatrics age group (less than 18 years). Only studies that fulfilled WHO 2008 or 2016 criteria for MPNs were included. We aimed to describe the clinical characteristics, vascular and long-term complications, types of driver mutations, and treatment approaches in pediatric patients with MPNs.

RESULTS

We reviewed 33 articles of available published literature from 2008 to 2022 and collected data from a total of 196 patients of the pediatric population. Among the cohort of patients, 139 had essential thrombocythemia (ET), 20 had polycythemia vera (PV), and 37 had primary myelofibrosis (PMF). The median age at the time of diagnosis for each disease varied, with 8.8 years for ET, 10 years for PV, and 3.6 years for MF. There was a slight difference in gender prevalence between both gender groups and all three diseases. The presenting symptoms were not mentioned in more than 50% of studies. We found that JAK2 was the most prevalent among all mutations. Both bleeding and thrombosis were present equally in ET, with 9% of cases complicated by bleeding and 9% complicated by thrombosis. Hemorrhagic events did not occur in patients with PV; thrombosis in children with MF was also not found. The progression into AML occurred in two patients with PV and one with ET.

CONCLUSION

Given the rarity of MPNs in pediatrics and their different characteristics compared with adults, we believe there is a need for unique diagnostic criteria to match the different molecular statuses in pediatrics. Based on our review, the incidence of MPN complications in pediatrics, including thrombotic events, hemorrhage, and leukemic transformation, differs from that in adults.