Smoking is associated with increased risk of myeloproliferative neoplasms: A general population-based cohort study

Aqueous humor perturbations in chronic smokers: a proteomic study

The detrimental effects of smoking are multisystemic and its effects on the eye health are significant. Smoking is a strong risk factor for age-related nuclear cataract, age-related macular degeneration, glaucoma, delayed corneal epithelial healing and increased risk of cystoid macular edema in patients with intermediate uveitis among others. We aimed to characterize the aqueous humor (AH) proteome in chronic smokers to gain insight into its perturbations and to identify potential biomarkers for smoking-associated ocular pathologies. Compared to the control group, chronic smokers displayed 67 (37 upregulated, 30 downregulated) differentially expressed proteins (DEPs). Analysis of DEPs from the biological point of view revealed that they were proteins involved in complement activation, lymphocyte mediated immunity, innate immune response, cellular oxidant detoxification, bicarbonate transport and platelet degranulation. From the molecular function point of view, DEPs were involved in oxygen binding, oxygen carrier activity, hemoglobin binding, peptidase/endopeptidase/cysteine-type endopeptidase inhibitory activity. Several of the upregulated proteins were acute phase reactant proteins such as clusterin, alpha-2-HS-glycoprotein, fibrinogen, alpha-1-antitrypsin, C4b-binding protein and serum amyloid A-2. Further research should confirm if these proteins might serve as biomarkers or therapeutic target for smoking-associated ocular diseases.

JAK2V617F mutation is highly prevalent in patients with ischemic stroke: a case-control study

Ischemic stroke has a high recurrence rate despite treatment. This underlines the significance of investigating new possible cerebrovascular risk factors, such as the acquired gene mutation JAK2V617F found in 3.1% of the general population. We aimed to investigate the prevalence of the JAK2V617F mutation in a population with ischemic stroke compared with that in matched controls. We enrolled 538 consecutive Danish patients with ischemic stroke (mean age, 69.5 ± 10.9 years; 39.2% female) within 7 days of symptom onset. Using multiple-adjusted conditional logistic regression analysis, we compared the prevalence of JAK2V617F with that in age- and sex-matched controls free of ischemic cerebrovascular disease (ICVD) from the Danish General Suburban Population Study. DNA was analyzed for JAK2V617F mutation using sensitive droplet digital polymerase chain reaction in patients and controls. Of the 538 patients with ischemic stroke, 61 (11.3%) had JAK2V617F mutation. There were no differences in patient demographics or cerebrovascular comorbidities between the patients with and without mutations. Patients with ischemic stroke were more likely to have the JAK2V617F mutation than matched controls, in whom the JAK2V617F prevalence was 4.4% (odds ratio, 2.37; 95% confidence interval, 1.57-3.58; P < .001). A subanalysis stratified by smoking history revealed that the association was strongest in current smokers (odds ratio, 4.78; 95% confidence interval, 2.22-10.28; P < .001). Patients with ischemic stroke were 2.4 times more likely to have the JAK2V617F mutation than matched controls without ICVD when adjusting for other cerebrovascular risk factors. This finding supports JAK2V617F mutation as a novel cerebrovascular risk factor.

Molecular Studies for the Early Detection of Philadelphia-Negative Myeloproliferative Neoplasms

JAK2 V617F is the predominant driver mutation in patients with Philadelphia-negative myeloproliferative neoplasms (MPN). JAK2 mutations are also frequent in clonal hematopoiesis of indeterminate potential (CHIP) in otherwise "healthy" individuals. However, the period between mutation acquisition and MPN diagnosis (known as latency) varies widely between individuals, with JAK2 mutations detectable several decades before diagnosis and even from birth in some individuals. Here, we will review the current evidence on the biological factors, such as additional mutations and chronic inflammation, which influence clonal expansion and may determine why some JAK2-mutated individuals will progress to an overt neoplasm during their lifetime while others will not. We will also introduce several germline variants that predispose individuals to CHIP (as well as MPN) identified from genome-wide association studies. Finally, we will explore possible mutation screening or interventions that could help to minimize MPN-associated cardiovascular complications or even delay malignant progression.

Mutations, inflammation and phenotype of myeloproliferative neoplasms

Knowledge on the myeloproliferative neoplasms (MPNs) - polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) - has accumulated since the discovery of the JAK/STAT-activating mutations associated with MPNs: JAK2V617F, observed in PV, ET and PMF; and the MPL and CALR mutations, found in ET and PMF. The intriguing lack of disease specificity of these mutations, and of the chronic inflammation associated with MPNs, triggered a quest for finding what precisely determines that MPN patients develop a PV, ET or PMF phenoptype. The mechanisms of action of MPN-driving mutations, and concomitant mutations (ASXL1, DNMT3A, TET2, others), have been extensively studied, as well as the role played by these mutations in inflammation, and several pathogenic models have been proposed. In parallel, different types of drugs have been tested in MPNs (JAK inhibitors, interferons, hydroxyurea, anagrelide, azacytidine, combinations of those), some acting on both JAK2 and inflammation. Yet MPNs remain incurable diseases. This review aims to present current, detailed knowledge on the pathogenic mechanisms specifically associated with PV, ET or PMF that may pave the way for the development of novel, curative therapies.

Deepening Our Understanding of the Factors Affecting Landscape of Myeloproliferative Neoplasms: What Do We Know about Them?

Myeloproliferative neoplasms (MPNs) arise from the uncontrolled proliferation of hematopoietic stem and progenitor cells in bone marrow. As with all tumors, the development of MPNs is a consequence of alterations in malignant cells and their interaction with other extrinsic factors that support and promote tumor progression. Since the discovery of driver mutations, much work has focused on studying and reviewing the genomic features of the disease but has neglected to delve into the important role that many other mechanisms may play. This review discusses the genetic component of MPNs but focuses mainly on some of the most relevant work investigating other non-genetic factors that may be crucial for the disease. The studies summarized here address MPN cell-intrinsic or -extrinsic factors and the interaction between them through transcriptomic, proteomic and microbiota studies, among others.

Frequency of JAK2V617F, MPL and CALR driver mutations and associated clinical characteristics in a Norwegian patient cohort with myeloproliferative neoplasms

Myeloproliferative neoplasms are hematological disorders characterized by increased production in one or more myeloid cell lines, associated with driver mutations in JAK2-, MPL- and CALR-genes. The aims of this study were to investigate the prevalence of these driver mutations in a Norwegian patient cohort with myeloproliferative neoplasms, and to assess whether the different mutations were associated with different clinical presentation and natural history.Results from 820 patients in whom analysis for JAK2V617F-, CALR- and MPL had been performed at Haukeland University Hospital in the period 2014-2019 were retrieved and analyzed together with clinical variables related to diagnosis, hematological blood parameters and complications, obtained from patient records.We identified 182 cases of myeloproliferative neoplasms: 78 with JAK2V617F, 28 with CALR-mutations, two with MPL-mutations and 23 cases without a driver mutation. There was a lower prevalence of JAK2V617F mutation than expected in the polycythemia vera group, likely related to overdiagnosis. In patients with essential thrombocytosis, we found significantly higher levels of hemoglobin and erythrocyte volume fraction for JAK2V617F-mutated disease, and significantly higher levels of platelets and lactate dehydrogenase for CALR-mutated disease. Patients with JAK2V617F-mutated primary myelofibrosis had significantly higher levels of hemoglobin, and there was an increased number of smokers or former smokers in this group compared to patients with CALR-mutations.Except for a lower prevalence of JAK2V617F-mutation in polycythemia vera, the mutational distribution in our patient cohort was similar to previous findings in other populations. The novel finding of a higher prevalence of smokers in JAK2V617F-mutated primary myelofibrosis warrants further investigation.

Disease and Clinical Characteristics of Patients With a Clinical Diagnosis of Myelofibrosis Enrolled in the MOST Study

BACKGROUND

Clinical characteristics and treatment patterns of patients with lower-risk myelofibrosis (MF) are not well described. This analysis from the MOST (NCT02953704) assessed the demographic and clinical characteristics and treatment patterns of patients with the clinical diagnosis of lower-risk MF at enrollment.

PATIENTS AND METHODS

MOST is an ongoing, prospective, observational study in patients with clinical diagnoses of MF or essential thrombocythemia enrolled at clinical practices throughout the United States. Patients included in the MF cohort (≥18 years of age) had low-risk MF by the Dynamic International Prognostic Scoring System or intermediate-1 (INT-1) risk MF (by age >65 years only) at enrollment. Patient data were entered into an electronic case report form during usual-care visits over a planned 36 month observation period.

RESULTS

Two hundred five patients were eligible for this analysis (low risk, n = 85; INT-1 risk, n = 120; median age, 68 years [range, 35-88]); 166 patients (81.0%) had mutation testing results available. The median time from MF diagnosis to enrollment was 1.8 years. Hemoglobin and hematocrit levels were below the normal range in 50.5% and 48.7% of patients, respectively. Nearly all (98.0%) patients had comorbid conditions, most commonly hypertension (49.8%). Fatigue was the most common physician-reported MF symptom (30.7%). At enrollment, 55.6% of patients were receiving MF-directed monotherapy, most frequently hydroxyurea (46.5%) or ruxolitinib (40.4%).

CONCLUSION

Future longitudinal analyses of data from MOST will help identify unmet needs and characterize how patients with lower-risk MF are managed throughout the disease course.

Environmental Factors, Lifestyle Risk Factors, and Host Characteristics Associated With Philadelphia Negative Myeloproliferative Neoplasm: A Systematic Review

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell disorders characterized by the overproduction of mature myeloid cells and are often associated with an acquired genetic mutation of Janus Kinase2V617F. Various epidemiological studies have indicated associations between environmental factors, lifestyle factors, and host characteristics with developing MPNs. This review aims to collect and summarize the existing information on these risk factors and establish their association with pathogenesis MPNs. Medline, Embase, PubMed, and grey literature were systematically searched using key terms for MPNs, and epidemiological study designs, that is, cross-sectional studies, case-control, and cohort, that investigated the risk factors for MPNs published were identified. Out of the 4621 articles identified, 20 met the selection criteria and were included in this review. Heterogeneity, study reliability, and bias were assessed. A significant association was found between smoking and the development of MPNs. This relationship has been explained by the substantial increase in several proinflammatory mediators and systematic oxidative stress causing hyperstimulation of myeloid compartments leading to the development of MPNs. Obesity was modestly linked with an increased risk of MPNs. The underlying mechanisms have been linked to changes in endocrine, metabolic, and inflammatory systems. No strong association was found between exposure to hazardous substances, that is, benzene and MPNs, but further investigation on the effects of increased levels and duration of exposure on hematopoietic stem cells will be beneficial. Unique individual and host variations have been determined as a modifier of disease pathogenesis and phenotype variations. There is a higher incidence rate of females developing MPNs, specifically ET, than males with higher PV incidence. Therefore, gender contributes to the heterogeneity in myeloproliferative neoplasm. Studies identified as part of this review are very diverse. Thus, further in-depth assessment to explore the role of these etiological factors associated with MPNs is warranted.

Inflammation in Myeloid Malignancies: From Bench to Bedside

Myeloid malignancies, stemming from a somatically mutated hematopoietic clone, can cause a wide variety of clinical consequences, including pancytopenia in myelodysplastic syndrome, overproduction of three myeloid lineages in myeloproliferative neoplasm, and the rapid growth of immature hematopoietic cells in acute myeloid leukemia (AML). It is becoming clear that inflammation is a hallmark feature of clonal myeloid conditions, ranging from clonal hematopoiesis of indeterminate potential to AML. Fundamental findings from laboratory research on inflammation in myeloid malignancies has potential implications for diagnosis, prognostication, and treatment in these diseases. In this review, we highlighted some pertinent basic science findings regarding the role of inflammation in myeloid malignancies and speculated how these findings could impact the clinical care of patients.

Tobacco use in the Myeloproliferative neoplasms: symptom burden, patient opinions, and care

BACKGROUND

Patients with Philadelphia-negative Myeloproliferative Neoplasms (MPN) suffer from numerous symptoms and decreased quality of life. Smoking is associated with an increased symptom burden in several malignancies. The aim of this study was to analyze the association between smoking and MPN-related symptom burden and explore MPN patients' opinions on smoking.

METHODS

A total of 435 patients with MPN participated in a cross-sectional internet-based survey developed by the Mayo Clinic and the Myeloproliferative Neoplasm Quality of Life Group. Patients reported their demographics, disease characteristics, tobacco use, and opinions on tobacco use. In addition, MPN-related symptoms were reported via the validated 10-item version of the Myeloproliferative Neoplasms Symptom Assessment Form.

RESULTS

Current/former smokers reported worse fatigue (mean severity 5.6 vs. 5.0, p = 0.02) and inactivity (mean severity 4.0 vs. 3.4, p = 0.03) than never smokers. Moreover, current/former smokers more frequently experienced early satiety (68.5% vs. 58.3%, p = 0.03), inactivity (79.9% vs. 71.1%, p = 0.04), and concentration difficulties (82.1% vs. 73.1%, p = 0.04). Although not significant, a higher total symptom burden was observed for current/former smokers (mean 30.4 vs. 27.0, p = 0.07). Accordingly, overall quality of life was significantly better among never smokers than current/former smokers (mean 3.5 vs. 3.9, p = 0.03). Only 43.2% of the current/former smokers reported having discussed tobacco use with their physician, and 17.5% did not believe smoking increased the risk of thrombosis.

CONCLUSION

The current study suggests that smoking may be associated with increased prevalence and severity of MPN symptoms and underscores the need to enhance patient education and address tobacco use in the care of MPN patients.

Recent Advances in the Use of Molecular Analyses to Inform the Diagnosis and Prognosis of Patients with Polycythaemia Vera

Genetic studies in the past decade have improved our understanding of the molecular basis of the BCR-ABL1-negative myeloproliferative neoplasm (MPN) polycythaemia vera (PV). Such breakthroughs include the discovery of the JAK2V617F driver mutation in approximately 95% of patients with PV, as well as some very rare cases of familial hereditary MPN caused by inherited germline mutations. Patients with PV often progress to fibrosis or acute myeloid leukaemia, both associated with very poor clinical outcome. Moreover, thrombosis and major bleeding are the principal causes of morbidity and mortality. As a result of increasingly available and economical next-generation sequencing technologies, mutational studies have revealed the prognostic relevance of a few somatic mutations in terms of thrombotic risk and risk of transformation, helping to improve the risk stratification of patients with PV. Finally, knowledge of the molecular basis of PV has helped identify targets for directed therapy. The constitutive activation of the tyrosine kinase JAK2 is targeted by ruxolitinib, a JAK1/JAK2 tyrosine kinase inhibitor for PV patients who are resistant or intolerant to cytoreductive treatment with hydroxyurea. Other molecular mechanisms have also been revealed, and numerous agents are in various stages of development. Here, we will provide an update of the recent published literature on how molecular testing can improve the diagnosis and prognosis of patients with PV and present recent advances that may have prognostic value in the near future.

Overview of Myeloproliferative Neoplasms: History, Pathogenesis, Diagnostic Criteria, and Complications

Myeloproliferative disorders are a group of diseases morphologically linked by terminal myeloid cell expansion that frequently evolve from one clinical phenotype to another and eventually progress to acute myeloid leukemia. Diagnostic criteria for the Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) have been established by the World Health Organization and they are recognized as blood cancers. MPNs have a complex and incompletely understood pathogenesis that includes systemic inflammation, clonal hematopoiesis, and constitutive activation of the JAK-STAT pathway. Complications, such as thrombosis and progression to overt forms of myelofibrosis and acute leukemia, contribute significantly to morbidity and mortality of patients with MPN.

The importance of evaluating specific myeloid malignancies in epidemiological studies of environmental carcinogens

INTRODUCTION

Although myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), myeloproliferative neoplasms (MPN) - including chronic myeloid leukemia (CML) - and myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are largely clinically distinct myeloid malignancies, epidemiological studies rarely examine them separately and often combine them with lymphoid malignancies, limiting possible etiological interpretations for specific myeloid malignancies.

METHODS

We systematically evaluated the epidemiological literature on the four chemical agents (1,3-butadiene, formaldehyde, benzene, and tobacco smoking, excluding pharmaceutical, microbial and radioactive agents, and pesticides) classified by the International Agency for Research on Cancer as having sufficient epidemiological evidence to conclude that each causes "myeloid malignancies." Literature searches of IARC Monographs and PubMed identified 85 studies that we critically assessed, and for appropriate subsets, summarized results using meta-analysis.

RESULTS

Only two epidemiological studies on 1,3-butadiene were identified, but reported findings were inadequate to evaluate specific myeloid malignancies. Studies on formaldehyde reported results for AML and CML - and not for MDS or MPN - but reported no increased risks. For benzene, several specific myeloid malignancies were evaluated, with consistent associations reported with AML and MDS and mixed results for CML. Studies of tobacco smoking examined all major myeloid malignancies, demonstrating consistent relationships with AML, MDS and MPN, but not with CML.

CONCLUSIONS

Surprisingly few epidemiological studies present results for specific myeloid malignancies, and those identified were inconsistent across studies of the same exposure, as well as across chemical agents. This exercise illustrates that even for agents classified as having sufficient evidence of causing "myeloid malignancies," the epidemiological evidence for specific myeloid malignancies is generally limited and inconsistent. Future epidemiological studies should report findings for the specific myeloid malignancies, as combining them post hoc - where appropriate - always remains possible, whereas disaggregation may not. Furthermore, combining results across possibly discrete diseases reduces the chances of identifying important malignancy-specific causal associations.

Epidemiology of the Philadelphia Chromosome-Negative Classical Myeloproliferative Neoplasms

Polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) comprise the BCR-ABL-negative classical myeloproliferative neoplasms (MPNs). These clonal myeloid diseases are principally driven by well-described molecular events; however, factors leading to their acquisition are not well understood. Beyond increasing age, male sex, and race/ethnicity differences, few consistent risk factors for the MPNs are known. PV and ET have an incidence of 0.5 to 4.0 and 1.1 to 2.0 cases per 100,000 person-years, respectively, and predict similar survival. PMF, which has an incidence of about 0.3 to 2.0 cases per 100,000 person-years, is associated with the shortest survival of the MPNs.

The Microenvironment in Myeloproliferative Neoplasms

Chronic inflammation is a hallmark of myeloproliferative neoplasms (MPNs), with elevated levels of proinflammatory cytokines being commonly found in all 3 subtypes. Systemic inflammation is responsible for the constitutional symptoms, thrombosis risk, premature atherosclerosis, and disease evolution in MPN. Although the neoplastic clone and their differentiated progeny drive the inflammatory process, they also induce ancillary cytokine secretion from nonmalignant cells. Here, the authors describe the inflammatory milieu in MPN based on soluble factors and cellular mediators. They also discuss the prognostic value of cytokine measurements in patients with MPN and potential therapeutic strategies that target the cellular players in inflammation.

Smoking impairs molecular response, and reduces overall survival in patients with chronic myeloproliferative neoplasms: A retrospective cohort study

The effects of smoking on the molecular response (MR) and overall survival (OS) in patients with chronic myeloproliferative neoplasms (MPNs) have not been investigated before. We analysed a historical cohort of 498 consecutive patients diagnosed with MPNs. Moreover, we analysed a subgroup of 270 consecutive patients with MPNs with > 1 measurement of the JAK2V617F variant allele frequency. The data were analysed using Kaplan-Meier plots and Cox regression analysis, along with linear regression models. In all patients, the rate of MR was significantly higher in never-smokers compared with current smokers in the univariate model (HR, 1·9; 95% CI, 1·1-3·3; P = 0·033) and the multivariate model (HR, 1·9; 95% CI, 1·1-3·5; P = 0·029). Similar findings were observed with different cut-off values for a partial MR. A subgroup analysis including only interferon-α2-treated patients showed similar results. In multivariate analyses, the OS was significantly better for never-smokers (HR, 0·46; 95% CI, 0·29-0·75; P = 0·002) than current smokers. The differences were more pronounced in the pegylated interferon-α2-treated patients. However, no significant interaction of interferon-α2 treatment was observed. In conclusion, we found that tobacco smoking reduced the rate of MR and OS in patients with MPNs. Cessation of smoking should be encouraged.

Anti-Glucosylsphingosine Autoimmunity, JAK2V617F-Dependent Interleukin-1β and JAK2V617F-Independent Cytokines in Myeloproliferative Neoplasms

Simple Summary

Inflammation plays a major role in myeloproliferative neoplasms (MPNs) as regulator of malignant cell growth and mediator of clinical symptoms. Yet chronic inflammation may also be an early event that facilitates the development of MPNs. Here we analysed 42 inflammatory cytokines and report that in patients as well as in UT-7 cell lines, interleukin-1β and interferon-induced protein 10 (IP-10) were the main inflammatory molecules found to be induced by JAK2V617F, the most frequent driving mutation in MPNs. All other inflammatory cytokines were not linked to JAK2V617F, which implies that inflammation likely precedes MPN development at least in subsets of MPN patients. Consistently, a possible cause of early, chronic inflammation may be auto-immunity against glucolipids: we report that 20% of MPN patients presented with anti-glucosylsphingoside auto-antibodies. Since existing treatments can reduce glucosylsphingoside, this lysosphingolipid could become a new therapeutic target for subsets of MPN patients, in addition to JAK2V617F and inflammation.

Abstract

Inflammatory cytokines play a major role in myeloproliferative neoplasms (MPNs) as regulators of the MPN clone and as mediators of clinical symptoms and complications. Firstly, we investigated the effect of JAK2V617F on 42 molecules linked to inflammation. For JAK2V617F-mutated patients, the JAK2V617F allele burden (%JAK2V617F) correlated with the levels of IL-1β, IL-1Rα, IP-10 and leptin in polycythemia vera (PV), and with IL-33 in ET; for all other molecules, no correlation was found. Cytokine production was also studied in the human megakaryocytic cell line UT-7. Wild-type UT-7 cells secreted 27/42 cytokines measured. UT-7 clones expressing 50% or 75% JAK2V617F were generated, in which the production of IL-1β, IP-10 and RANTES was increased; other cytokines were not affected. Secondly, we searched for causes of chronic inflammation in MPNs other than driver mutations. Since antigen-driven selection is increasingly implicated in the pathogenesis of blood malignancies, we investigated whether proinflammatory glucosylsphingosine (GlcSph) may play a role in MPNs. We report that 20% (15/75) of MPN patients presented with anti-GlcSph IgGs, distinguished by elevated levels of 11 cytokines. In summary, only IL-1β and IP-10 were linked to JAK2V617F both in patients and in UT-7 cells; other inflammation-linked cytokines in excess in MPNs were not. For subsets of MPN patients, a possible cause of inflammation may be auto-immunity against glucolipids.

Myeloproliferative blood cancers as a human neuroinflammation model for development of Alzheimer's disease: evidences and perspectives

Chronic inflammation and involvement of myeloid blood cells are associated with the development of Alzheimer's disease (AD). Chronic inflammation is a highly important driving force for the development and progression of the chronic myeloproliferative blood cancers (MPNs), which are characterized by repeated thrombotic episodes years before MPN-diagnosis, being elicited by elevated erythrocytes, leukocytes, and platelets. Mutations in blood cells, the JAK2V617F and TET2-mutations, contribute to the inflammatory and thrombogenic state. Herein, we discuss the MPNs as a human neuroinflammation model for AD development, taking into account the many shared cellular mechanisms for reduction in cerebral blood, including capillary stalling with plugging of blood cells in the cerebral microcirculation. The therapeutic consequences of an association between MPNs and AD are immense, including reduction in elevated cell counts by interferon-alpha2 or hydroxyurea and targeting the chronic inflammatory state by JAK1-2 inhibitors, e.g., ruxolitinib, in the future treatment of AD.

E-Cigarette Exposure Decreases Bone Marrow Hematopoietic Progenitor Cells

Electronic cigarettes (E-cigs) generate nicotine containing aerosols for inhalation and have emerged as a popular tobacco product among adolescents and young adults, yet little is known about their health effects due to their relatively recent introduction. Few studies have assessed the long-term effects of inhaling E-cigarette smoke or vapor. Here, we show that two months of E-cigarette exposure causes suppression of bone marrow hematopoietic stem and progenitor cells (HSPCs). Specifically, the common myeloid progenitors and granulocyte-macrophage progenitors were decreased in E-cig exposed animals compared to air exposed mice. Competitive reconstitution in bone marrow transplants was not affected by two months of E-cig exposure. When air and E-cig exposed mice were challenged with an inflammatory stimulus using lipopolysaccharide (LPS), competitive fitness between the two groups was not significantly different. However, mice transplanted with bone marrow from E-cigarette plus LPS exposed mice had elevated monocytes in their peripheral blood at five months post-transplant indicating a myeloid bias similar to responses of aged hematopoietic stem cells (HSC) to an acute inflammatory challenge. We also investigated whether E-cigarette exposure enhances the selective advantage of hematopoietic cells with myeloid malignancy associated mutations. E-cigarette exposure for one month slightly increased JAK2V617F mutant cells in peripheral blood but did not have an impact on TET2-/- cells. Altogether, our findings reveal that chronic E-cigarette exposure for two months alters the bone marrow HSPC populations but does not affect HSC reconstitution in primary transplants.

Impact of Host, Lifestyle and Environmental Factors in the Pathogenesis of MPN

Philadelphia-negative myeloproliferative neoplasms (MPNs) occur when there is over-production of myeloid cells stemming from hematopoietic stem cells with constitutive activation of JAK/STAT signaling, with JAK2^V617F being the most commonly occurring somatic driver mutation. Chronic inflammation is a hallmark feature of MPNs and it is now evident that inflammation is not only a symptom of MPN but can also provoke development and precipitate progression of disease. Herein we have considered major MPN driver mutation independent host, lifestyle, and environmental factors in the pathogenesis of MPN based upon epidemiological and experimental data. In addition to the traditional risk factors such as advanced age, there is evidence to indicate that inflammatory stimuli such as smoking can promote and drive MPN clone emergence and expansion. Diet induced inflammation could also play a role in MPN clonal expansion. Recognition of factors associated with MPN development support lifestyle modifications as an emerging therapeutic tool to restrain inflammation and diminish MPN progression.

Key Role of Inflammation in Myeloproliferative Neoplasms: Instigator of Disease Initiation, Progression. and Symptoms

PURPOSE OF REVIEW

Chronic inflammation is a characteristic feature of myeloproliferative neoplasm (MPN) and impacts many aspects of the disease including initiation, progression, and symptomatology.

RECENT FINDINGS

The chronic inflammatory state of MPN results from disruption of immune signaling pathways leading to overproduction of inflammatory cytokines by both the neoplastic clones and bystander immune cells. This chronic inflammation may allow for the neoplastic clone to gain a selective advantage. The symptomatic burden felt by MPN patients may be a result of the chronic inflammation associated with MPN, as several cytokines have been linked with different symptoms. Pharmacologic as well as nonpharmacologic treatments of the inflammatory component of this disease may lead to decreased symptomatic burden, prevention of disease progression, and improvement in overall disease trajectory. Inflammation plays a key role in the pathogenesis of MPN and represents an important therapeutic target.

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.

Epidemiology of the classical myeloproliferative neoplasms: The four corners of an expansive and complex map

The classical myeloproliferative neoplasms (MPNs), specifically chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF), represent clonal myeloid disorders whose pathogenesis is driven by well-defined molecular abnormalities. In this comprehensive review, we summarize the epidemiological literature and present our own analysis of the most recent the Surveillance, Epidemiology, and End Results (SEER) program data through 2016. Older age and male gender are known risk factors for MPNs, but the potential etiological role of other variables is less established. The incidences of CML, PV, and ET are relatively similar at 1.0-2.0 per 100,000 person-years in the United States, while PMF is rarer with an incidence of 0.3 per 100,000 person-years. The availability of tyrosine kinase inhibitor therapy has dramatically improved CML patient outcomes and yield a life expectancy similar to the general population. Patients with PV or ET have better survival than PMF patients.

Loss-of-function polymorphism in IL6R reduces risk of JAK2V617F somatic mutation and myeloproliferative neoplasm: A Mendelian randomization study

BACKGROUND

Whether inflammation is independently associated with development of JAK2V617F mutation and myeloproliferative neoplasm is not clear. We tested the hypothesis that a loss-of-function polymorphism in IL6R (marked by rs4537545) reduces risk of JAK2V617F mutation and myeloproliferative neoplasm in a Mendelian randomization study.

METHODS

We genotyped 107,969 Danes from the Copenhagen General Population Study for the IL6R rs4537545 genotype, where the T-allele is associated with impaired interleukin-6 receptor signaling and reduced inflammation. JAK2V617F was examined in a subset of 49,143 individuals. We investigated the association between IL6R rs4537545 and risk of JAK2V617F using logistic regression and myeloproliferative neoplasm using Cox regression.

FINDINGS

36,871 were non-carriers, 52,500 heterozygotes, and 18,598 homozygotes for the T-allele of the IL6R rs4537545 genotype. Among 107,969 individuals, 352 were diagnosed with myeloproliferative neoplasm, and among 49,143 individuals, 62 were JAK2V617F-positive (of these 62 individuals, 46 had myeloproliferative neoplasm diagnosed). Compared to non-carriers, age- and sex-adjusted odds ratios for risk of JAK2V617F were 0·55(95%CI:0·32-0·94) in heterozygotes, 0·51(0·24-1·12) in homozygotes, 0·54(0·33-0·89) in carriers, and 0·66(0·45-0·96) per T-allele. Compared to non-carriers, age- and sex-adjusted hazard ratios for risk of myeloproliferative neoplasm were 0·82(95% CI: 0·65-1·02) in heterozygotes, 0·65(0·47-0·91) in homozygotes, 0·77(0·63-0·96) in carriers, and 0·81(0·70-0·94) per T-allele. Associations were primarily observed for polycythaemia vera and myelofibrosis, and for JAK2V617F-positive myeloproliferative neoplasm.

INTERPRETATION

A loss-of-function polymorphism in IL6R reduces risk of JAK2V617F mutation and myeloproliferative neoplasm. This finding supports inflammation as an independent risk factor for JAK2V617F mutation and myeloproliferative neoplasm and indicates that therapeutics designed to block interleukin-6 receptor signaling might prevent or retard progression of myeloproliferative neoplasm.

FUNDING

Karen Elise Jensen Foundation.

Smoking, blood cells and myeloproliferative neoplasms: meta-analysis and Mendelian randomization of 2·3 million people

Meta-analyses and Mendelian randomization (MR) may clarify the associations of smoking, blood cells and myeloproliferative neoplasms (MPN). We investigated the association of smoking with blood cells in the Danish General Suburban Population Study (GESUS, n = 11 083), by meta-analyses (including GESUS) of 92 studies (n = 531 741) and MR of smoking variant CHRNA3 (rs1051730[A]) in UK Biobank, and with MPN in a meta-analysis of six studies (n (total/cases):1 425 529/2187), totalling 2 307 745 participants. In the meta-analysis the random-effects standardized mean difference (SMD) in current smokers versus non-smokers was 0·82 (0·75-0·89, P = 2·0 * 10^-108 ) for leukocytes, 0·09 (-0·02 to 0·21, P = 0·12) for erythrocytes, 0·53 (0·42-0·64, P = 8·0 * 10^-22 ) for haematocrit, 0·42 (0·34-0·51, P = 7·1 * 10^-21 ) for haemoglobin, 0·19 (0·08-0·31, P = 1·2 * 10^-3 ) for mean corpuscular haemoglobin (MCH), 0·29 (0·19-0·39, P = 1·6 * 10^-8 ) for mean corpuscular volume (MCV), and 0·04 (-0·04 to 0·13, P = 0·34) for platelets with trends for ever/ex-/current smokers, light/heavy smokers and female/male smokers. Analyses presented high heterogeneity but low publication bias. Per allele in CHRNA3, cigarettes per day in current smokers was associated with increased blood cell counts (leukocytes, neutrophils), MCH, red cell distribution width (RDW) and MCV. The pooled fixed-effects odds ratio for MPN was 1·44 [95% confidence interval (CI): 1·33-1·56; P = 1·8 * 10^-19 ; I²  = 0%] in current smokers, 1·29 (1·15-1·44; P = 8·0 * 10^-6 ; I²  = 0%) in ex-smokers, 1·49 (1·26-1·77; P = 4·4 * 10^-6 ; I²  = 0%) in light smokers and 2·04 (1·74-2·39, P = 2·3 * 10^-18 ; I²  = 51%) in heavy smokers compared with non-smokers. Smoking is observationally and genetically associated with increased leukocyte counts and red blood cell indices (MCH, MCV, RDW) and observationally with risk of MPN in current and ex-smokers versus non/never-smokers.

Prevalence and phenotypes of JAK2 V617F and calreticulin mutations in a Danish general population

The JAK2 V617F and calreticulin mutations (CALR) are frequent within myeloproliferative neoplasms (MPNs). JAK2 V617F has been detected in the general population, but no studies have previously investigated the CALR prevalence. Thus, we aimed to determine the CALR and JAK2 V617F population prevalence and assess the biochemical profile and lifestyle factors in mutation-positive individuals with and without MPN. 19 958 eligible participants, enrolled from 2010-2013, from the Danish General Suburban Population Study were screened for JAK2 V617F and CALR by droplet digital polymerase chain reaction with (3.2%) mutation positives of which 16 (2.5%) had MPN at baseline. Of 645 participants, 613 were JAK2 V617F positive, and 32 were CALR positive, corresponding to a population prevalence of 3.1% (confidence interval [CI], 2.8-3.3) and 0.16% (CI, 0.11-0.23), respectively. Increasing age, smoking, and alcohol were risk factors for the mutations. JAK2 V617F positives with and without MPN presented elevated odds for prevalent venous thromboembolism. The odds ratio for a diagnosis of MPN per percentage allele burden was 1.14 (95% CI, 1.09-1.18; P = 1.6 × 10−10). Mutation positives displayed higher blood cell counts than nonmutated participants, and 42% of mutation positives without MPN presented elevation of ≥1 blood cell counts; 80 (13%) even presented blood cell counts in accordance with current MPN diagnostic criteria. In conclusion, we present a novel population prevalence of CALR and a JAK2 V617F prevalence that is 3 to 30 times higher compared with less sensitive methods. Mutation-positive non-MPNs with elevated blood cell counts raise concerns of MPN underdiagnosis in the population.

Smoking and Increased White and Red Blood Cells

Objective—

Whether tobacco smoking causally affects white and red blood cells and thrombocyte counts is unknown. Using a Mendelian randomization approach, we tested the hypothesis that smoking causes increases in these blood cell indices.

Approach and Results—

We included 104 607 white Danes aged 20 to 100 years from the Copenhagen General Population Study with information on blood cell indices, smoking habits, and CHRNA3 (alpha 3 nicotinic cholinergic receptor) rs1051730 genotype, where the T allele causes higher tobacco consumption; 41 759 were former smokers and 17 852 current smokers. In multivariable adjusted observational analyses and compared with never smokers, white blood cells were associated with up to 19% increases, thrombocytes with up to 4.7% increases, and red blood cell indices with up to 2.3% increases in former and current smokers. All associations were dose dependent, with tobacco consumption but for white blood cells and thrombocytes also dependent on smoking cessation time in former smokers; highest increases were for <1-year smoking cessation and lowest increases for >10-year smoking cessation. In age- and sex-adjusted genetic analyses, percent differences per T allele increase in current smokers were 1.15% (95% CI, 0.61%–1.68%) for leukocytes, 1.07% (0.38%–1.76%) for neutrophils, 1.34% (0.66%–2.02%) for lymphocytes, 1.50% (0.83%–2.18%) for monocytes, −0.60% (−1.91% to 0.74%) for eosinophils, 0.17% (−0.94% to 1.29%) for basophils, 0.38% (−0.17% to 0.93%) for thrombocytes, 0.04% (−0.14% to 0.23%) for erythrocytes, 0.34% (0.17% to 0.50%) for hematocrit, 0.26% (0.09% to 0.43%) for hemoglobin, and 0.29% (0.18% to 0.41%) for mean corpuscular volume.

Conclusions—

Smoking causes increased blood leukocytes, neutrophils, lymphocytes, and monocytes, as well as increased hematocrit, hemoglobin, and mean corpuscular volume. The observational smoking relationships were long term for white blood cells and short term for red blood cell indices.

Smoking is associated with increased risk of myeloproliferative neoplasms: A general population-based cohort study

Background

Former studies on smoking as a risk factor for Philadelphia‐negative myeloproliferative neoplasms (MPNs) have mainly been carried out in women's cohorts and studies with various definitions of MPNs. Herein, we conducted a cohort study with register‐based follow‐up of a general population from Denmark, to validate and substantiate prior observations.

Methods

In the Danish Health Examination Survey cohort, we used the Cox proportional‐hazards model adjusted for age, sex, body mass index, and level of education, to calculate hazard ratios (HRs), to investigate, whether daily smokers or occasional/ex‐smokers had an increased risk of MPNs compared to never‐smokers.

Results

From the time of data collection (September 2007 to October 2008) until 1 January 2015, 70 individuals were diagnosed with MPNs among 75 896 study participants. Similar results were observed in both the age and sex adjusted analysis and the multivariable analysis. The multivariable HR of any MPN diagnosis for daily smokers was 2.5 (95% CI: 1.3‐5.0). For essential thrombocytosis, polycythemia vera, myelofibrosis, and MPN‐unclassified, the HRs were 1.8 (95% CI: 0.5‐5.8), 1.7 (95% CI: 0.5‐5.8), 4.3 (95% CI: 0.9‐19), and 6.2 (95% CI: 1.5‐25), respectively. Among occasional/ex‐smokers the corresponding HRs were 1.9 (95% CI: 1.1‐3.3), 1.5 (95% CI: 0.6‐3.7), 0.8 (95% CI: 0.3‐2.4), 0.9 (95% CI: 0.2‐4.4), and 6.2 (95% CI: 1.8‐21). Participants, who smoked >15 g/day, had an overall HR of 3.4 (95% CI: 1.4‐8.2) for any MPN diagnosis, while participants who smoked ≤15 g/day, had an overall HR of 2.1 (95% CI: 0.9‐4.7).

Conclusion

Smoking was associated with MPN development when comparing smokers and never‐smokers. Further studies investigating smoking in MPNs are warranted to substantiate our findings.