Neutrophils from chronic lymphocytic leukemia patients exhibit an increased capacity to release extracellular traps (NETs)

Single-cell dissection reveals immunosuppressive F13A1+ macrophage as a hallmark for multiple primary lung cancers

BACKGROUND

The increasing prevalence of multiple primarylung cancers (MPLCs) presents challenges to current diagnostic and clinicalmanagement approaches. However, the molecular mechanisms driving MPLCdevelopment and distinguishing it from solitary primary lung cancers (SPLCs)remain largely unexplored.

METHODS

We performed a comparative single-cell RNAsequencing (scRNA-seq) analysis on tumour and adjacent para-tumour tissues fromMPLC and SPLC patients to comparatively evaluate their immunological landscapes.Additionally, multiplex immunofluorescence (mIF) staining and independentvalidation datasets were used to confirm findings.

RESULTS

MPLCs and SPLCs share significant similarities in genetic, transcriptomic and immune profiles, suggesting common therapeutic strategies such as EGFR-TKIs andICIs. Notably, an immunosuppressive macrophage subtype, F13A1+ Macrophage (Mϕ), is specifically enriched in MPLCs. This subtype overexpresses M2 macrophagemarkers and exhibits up-regulation of SPP1-CD44/CCL13-ACKR1 interactions, indicatingits role in shaping the immunosuppressive tumour microenvironment and promotingtumour growth in MPLCs.

CONCLUSIONS

This study unveils shared molecular mechanismsbetween MPLCs and SPLCs, while identifying MPLC-specific cellular and molecularfeatures, such as the role of F13A1+ macrophages. The findings provide novelinsights into MPLC pathogenesis, supporting the development of targetedtherapeutic strategies.

KEY POINTS

Comparative scRNA-seq analysis reveals significant similarities in genetic, transcriptomicand immune profiles between MPLCs and SPLCs. Identification of a unique immunosuppressive F13A1+ macrophage subtype, preferentially enriched in MPLCs, linked to immune evasion and tumourprogression. SPP1-CD44/CCL13-ACKR1 interactions are crucial in MPLC tumour microenvironment, indicating potential targets for therapeutic intervention.

Phenotypical differences of neutrophils patrolling tumour-draining lymph nodes in head and neck cancer

BACKGROUND

The complexity and heterogeneity of neutrophils are recognized, especially their roles in modulating inflammation and cancer immune responses. The detailed functions of neutrophils in human tumour-draining lymph nodes (TDLNs), specifically in the context of head and neck cancer, remain inadequately characterized.

AIM

This study aims to delineate the phenotypic diversity of neutrophils in TDLNs, non-tumour-draining lymph nodes (nTDLNs) from patients with oral squamous cell carcinoma (OSCC), and to evaluate their correlation with clinical outcomes.

METHODS

A flow cytometry-based investigation.

RESULTS

Neutrophils manifest a tissue-specific heterogeneity with significant phenotypic differences between compartments. A substantial fraction of neutrophils displayed an activated CD16highCD62Ldim profile in TDLNs, more prominent in patients with advanced T stages, implicating their involvement in the disease's progression. Notably, the presence of this activated neutrophil phenotype in TDLNs was strongly associated with poorer patient prognosis.

CONCLUSIONS

The study confirms the heterogeneity of neutrophils in human TDLNs, aligning with findings from animal models but extending them to show clinical relevance in human disease. The correlation of neutrophil phenotypes with cancer progression and prognosis emphasizes the importance of these cells in the tumour-microenvironment. The data suggests a future possibility to develop targeted therapies that modulate the neutrophilic response in OSCC.

Neutrophils in the premetastatic niche: key functions and therapeutic directions

Metastasis has been one of the primary reasons for the high mortality rates associated with tumours in recent years, rendering the treatment of current malignancies challenging and representing a significant cause of recurrence in patients who have undergone surgical tumour resection. Halting tumour metastasis has become an essential goal for achieving favourable prognoses following cancer treatment. In recent years, increasing clarity in understanding the mechanisms underlying metastasis has been achieved. The concept of premetastatic niches has gained widespread acceptance, which posits that tumour cells establish a unique microenvironment at distant sites prior to their migration, facilitating their settlement and growth at those locations. Neutrophils serve as crucial constituents of the premetastatic niche, actively shaping its microenvironmental characteristics, which include immunosuppression, inflammation, angiogenesis and extracellular matrix remodelling. These characteristics are intimately associated with the successful engraftment and subsequent progression of tumour cells. As our understanding of the role and significance of neutrophils in the premetastatic niche deepens, leveraging the presence of neutrophils within the premetastatic niche has gradually attracted the interest of researchers as a potential therapeutic target. The focal point of this review revolves around elucidating the involvement of neutrophils in the formation and shaping of the premetastatic niche (PMN), alongside the introduction of emerging therapeutic approaches aimed at impeding cancer metastasis.

TRIM8 as a predictor for prognosis in childhood acute lymphoblastic leukemia based on a signature of neutrophil extracellular traps

Background

Neutrophil extracellular traps (NETs) can be attributed to the metastasis, occurrence, and immune evasion of cancer cells. We investigated the prognostic value of NET-related genes in childhood acute lymphoblastic leukemia (cALL) patients.

Methods

Differential gene expression analysis was conducted on samples collected from public databases. Grouping them based on the expression level of NET-related genes, we assessed the correlation between immune cell types and the risk score for having a poor prognosis of cALL, with an evaluation of the sensitivity of drugs used in cALL. We further divided the groups, integrating survival data. Subsequently, methods including multivariable Cox algorithms, least absolute shrinkage and selection operator (LASSO), and univariable were utilized to create a risk model predicting prognosis. Experiments in cell lines and animals were performed to explore the functions of TRIM8, a gene selected by the model. To validate the role of TRIM8 in leukemia development, lentivirus-mediated overexpression or knockdown of TRIM8 was employed in mice with T-ALL and B-ALL.

Results

Kaplan-Meier (KM) analysis underscored the importance of differentially expressed genes identified in the groups divided by genes participated in NETs, with enrichment analysis showing the mechanism. Correlation analysis revealed significant associations with B cells, NK cells, mast cells, T cells, plasma cells, dendritic cells, and monocytes. The IC50 values of drugs such as all-trans-retinoic acid (ATRA), axitinib, doxorubicin, methotrexate, sorafenib, and vinblastine were increased, while dasatinib exhibited a lower IC50. A total of 13 NET-related genes were selected in constructing the risk model. In the training, testing, and merged cohorts, KM analysis demonstrated significantly improved survival for low-risk cALL patients compared to high-risk cALL patients (p < 0.001). The area under the curve (AUC) indicated strong predictive performance. Experiments in Jurkat and SUP-B15 revealed that TRIM8 knockdown decreased the proliferation of leukemia cell lines. Further experiments demonstrated a more favorable prognosis in mice with TRIM8-knockdown leukemia cells. Results of cell lines and animals showed better outcomes in prognosis when TRIM8 was knocked down.

Conclusion

We identified a novelty in a prognostic model that could aid in the development of personalized treatments for cALL patients. Furthermore, it revealed that the expression of TRIM8 is a contributing factor to the proliferation of leukemia cells and worsens the prognosis of cALL.

Cross-talk between leukemic and immune cells at the tumor microenvironment in chronic lymphocytic leukemia: An update review

Chronic lymphocytic leukemia (CLL) is a mature-type B cell malignancy correlated with significant changes and defects in both the innate and adaptive arms of the immune system, together with a high dependency on the tumor microenvironment. Overall, the tumor microenvironment (TME) in CLL provides a supportive niche for leukemic cells to grow and survive, and interactions between CLL cells and the TME can contribute to disease progression and treatment resistance. Therefore, the increasing knowledge of the complicated interaction between immune cells and tumor cells, which is responsible for immune evasion and cancer progression, has provided an opportunity for the development of new therapeutic approaches. In this review, we outline tumor microenvironment-driven contributions to the licensing of immune escape mechanisms in CLL patients.

Risk score constructed with neutrophil extracellular traps-related genes predicts prognosis and immune microenvironment in multiple myeloma

Background

Multiple myeloma (MM) exhibits considerable heterogeneity in treatment responses and survival rates, even when standardized care is administered. Ongoing efforts are focused on developing prognostic models to predict these outcomes more accurately. Recently, neutrophil extracellular traps (NETs) have emerged as a potential factor in MM progression, sparking investigation into their role in prognostication.

Methods

In this study, a multi-gene risk scoring model was constructed using the intersection of NTEs and differentially expressed genes (DEGs), applying the least absolute shrinkage and selection operator (LASSO) Cox regression model. A nomogram was established, and the prognostic model's effectiveness was determined via Kaplan-Meier survival analysis, receiver operating characteristic (ROC) curve, and decision curve analysis (DCA). The ESTIMATE algorithm and immune-related single-sample gene set enrichment analysis (ssGSEA) were employed to evaluate the level of immune infiltration. The sensitivity of chemotherapy drugs was assessed using the Genomics of Drug Sensitivity in Cancer (GDSC) database. Ultimately, the presence of the detected genes was confirmed through quantitative real-time polymerase chain reaction (qRT-PCR) analysis in MM cell specimens.

Results

64 NETs-DEGs were yielded, and through univariate Cox regression and LASSO regression analysis, we constructed a risk score composed of six genes: CTSG, HSPE1, LDHA, MPO, PINK1, and VCAM1. MM patients in three independent datasets were classified into high- and low-risk groups according to the risk score. The overall survival (OS) of patients in the high-risk group was significantly reduced compared to the low-risk group. Furthermore, the risk score was an independent predictive factor for OS. In addition, interactions between the risk score, immune score, and immune cell infiltration were investigated. Further analysis indicated that patients in the high-risk group were more sensitive to a variety of chemotherapy and targeted drugs, including bortezomib. Moreover, the six genes provided insights into the progression of plasma cell disorders.

Conclusion

This study offers novel insights into the roles of NETs in prognostic prediction, immune status, and drug sensitivity in MM, serving as a valuable supplement and enhancement to existing grading systems.

Role of the tumor microenvironment in CLL pathogenesis

Chronic lymphocytic leukemia (CLL) cells extensively interact with and depend on their surrounding tumor microenvironment (TME). The TME encompasses a heterogeneous array of cell types, soluble signals, and extracellular vesicles, which contribute significantly to CLL pathogenesis. CLL cells and the TME cooperatively generate a chronic inflammatory milieu, which reciprocally reprograms the TME and activates a signaling network within CLL cells, promoting their survival and proliferation. Additionally, the inflammatory milieu exerts chemotactic effects, attracting CLL cells and other immune cells to the lymphoid tissues. The intricate CLL-TME interactions also facilitate immune evasion and compromise leukemic cell surveillance. We also review recent advances that have shed light on additional aspects that are substantially influenced by the CLL-TME interplay.

Deregulation of New Cell Death Mechanisms in Leukemia

Hematological malignancies are among the top five most frequent forms of cancer in developed countries worldwide. Although the new therapeutic approaches have improved the quality and the life expectancy of patients, the high rate of recurrence and drug resistance are the main issues for counteracting blood disorders. Chemotherapy-resistant leukemic clones activate molecular processes for biological survival, preventing the activation of regulated cell death pathways, leading to cancer progression. In the past decade, leukemia research has predominantly centered around modulating the well-established processes of apoptosis (type I cell death) and autophagy (type II cell death). However, the development of therapy resistance and the adaptive nature of leukemic clones have rendered targeting these cell death pathways ineffective. The identification of novel cell death mechanisms, as categorized by the Nomenclature Committee on Cell Death (NCCD), has provided researchers with new tools to overcome survival mechanisms and activate alternative molecular pathways. This review aims to synthesize information on these recently discovered RCD mechanisms in the major types of leukemia, providing researchers with a comprehensive overview of cell death and its modulation.

Targeting neutrophil extracellular traps: A novel strategy in hematologic malignancies

Neutrophil extracellular traps (NETs) have emerged as a critical factor in malignant hematologic disease pathogenesis. These structures, comprising DNA, histones, and cytoplasmic proteins, were initially recognized for their role in immune defense against microbial threats. Growing evidence suggests that NETs contribute to malignant cell progression and dissemination, representing a double-edged sword. However, there is a paucity of reports on its involvement in hematological disorders. A comprehensive understanding of the intricate relationship between malignant cells and NETs is necessary to explore effective therapeutic strategies. This review highlights NET formation and mechanisms underlying disease pathogenesis. Moreover, we discuss recent advancements in targeted inhibitor development for selective NET disruption, empowering precise design and efficacious therapeutic interventions for malignant hematologic diseases.

The Complex Role of Thrombin in Cancer and Metastasis: Focus on Interactions with the Immune System

Thrombin, a pleiotropic enzyme involved in coagulation, plays a crucial role in both procoagulant and anticoagulant pathways. Thrombin converts fibrinogen into fibrin, initiates platelet activation, and promotes clot formation. Thrombin also activates anticoagulant pathways, indirectly inhibiting factors involved in coagulation. Tissue factor triggers thrombin generation, and the overexpression of thrombin in various cancers suggests that it is involved in tumor growth, angiogenesis, and metastasis. Increased thrombin generation has been observed in cancer patients, especially those with metastases. Thrombin exerts its effects through protease-activated receptors (PARs), particularly PAR-1 and PAR-2, which are involved in cancer progression, angiogenesis, and immunological responses. Thrombin-mediated signaling promotes angiogenesis by activating endothelial cells and platelets, thereby releasing proangiogenic factors. These functions of thrombin are well recognized and have been widely described. However, in recent years, intriguing new findings concerning the association between thrombin activity and cancer development have come to light, which justifies a review of this research. In particular, there is evidence that thrombin-mediated events interact with the immune system, and may regulate its response to tumor growth. It is also worth reevaluating the impact of thrombin on thrombocytes in conjunction with its multifaceted influence on tumor progression. Understanding the role of thrombin/PAR-mediated signaling in cancer and immunological responses is crucial, particularly in the context of developing immunotherapies. In this systematic review, we focus on the impact of the thrombin-related immune system response on cancer progression.

A neutrophil extracellular trap-related risk score predicts prognosis and characterizes the tumor microenvironment in multiple myeloma

Multiple myeloma (MM) is a distinguished hematologic malignancy, with existing studies elucidating its interaction with neutrophil extracellular traps (NETs), which may potentially facilitate tumor growth. However, systematic investigations into the role of NETs in MM remain limited. Utilizing the single-cell dataset GSE223060, we discerned active NET cell subgroups, namely neutrophils, monocytes, and macrophages. A transcriptional trajectory was subsequently constructed to comprehend the progression of MM. Following this, an analysis of cellular communication in MM was conducted with a particular emphasis on neutrophils, revealing an augmentation in interactions albeit with diminished strength, alongside abnormal communication links between neutrophils and NK cells within MM samples. Through the intersection of differentially expressed genes (DEGs) between NET active/inactive cells and MM versus healthy samples, a total of 316 genes were identified. This led to the development of a 13-gene risk model for prognostic prediction based on overall survival, utilizing transcriptomics dataset GSE136337. The high-risk group manifested altered immune infiltration and heightened sensitivity to chemotherapy. A constructed nomogram for predicting survival probabilities demonstrated encouraging AUCs for 1, 3, and 5-year survival predictions. Collectively, our findings unveil a novel NET-related prognostic signature for MM, thereby providing a potential avenue for therapeutic exploration.

Immune Dysfunction and Infection - Interaction between CLL and Treatment: A Reflection on Current Treatment Paradigms and Unmet Needs

BACKGROUND

Chronic lymphocytic leukemia (CLL) is a hematological malignancy characterized by immune dysfunction, which significantly contributes to increased morbidity and mortality due to infections.

SUMMARY

Advancement in therapeutic strategies based on combination chemoimmunotherapy and targeted treatment have increased life expectancy for patients affected by CLL. However, mortality and morbidity due to infection showed no improvement over the last decades. Although therapy options are highly efficient in targeting leukemic cells, several studies highlighted the interactions of different treatments with the tumor microenvironment immune components, significantly impacting their clinical efficacy and fostering increased risk of infections.

KEY MESSAGES

Given the profound immune dysfunction caused by CLL itself, treatment can thus represent a double-edged sword. Thus, it is essential to increase our understanding and awareness on how conventional therapies affect the disease-microenvironment-infection axis to ensure the best personalized strategy for each patient. This requires careful consideration of the advantages and disadvantages of efficient treatments, whether chemoimmunotherapy or targeted combinations, leading to risk of infectious complications. To this regard, our machine learning-based algorithm CLL Treatment-Infection Model, currently implemented into the local electronic health record system for Eastern Denmark, aims at early identification of patients at high risk of serious infections (PreVent-ACaLL; NCT03868722). We here review strategies for management of immune dysfunction and infections in CLL.

Immune Checkpoint Inhibitors, Small-Molecule Immunotherapies and the Emerging Role of Neutrophil Extracellular Traps in Therapeutic Strategies for Head and Neck Cancer

Immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment of many cancer types, including head and neck cancers (HNC). When checkpoint and partner proteins bind, these send an "off" signal to T cells, which prevents the immune system from destroying tumor cells. However, in HNC, and indeed many other cancers, more people do not respond and/or suffer from toxic effects than those who do respond. Hence, newer, more effective approaches are needed. The challenge to durable therapy lies in a deeper understanding of the complex interactions between immune cells, tumor cells and the tumor microenvironment. This will help develop therapies that promote lasting tumorlysis by overcoming T-cell exhaustion. Here we explore the strengths and limitations of current ICI therapy in head and neck squamous cell carcinoma (HNSCC). We also review emerging small-molecule immunotherapies and the growing promise of neutrophil extracellular traps in controlling tumor progression and metastasis.

B Cell Chronic Lymphocytic Leukemia Development in Mice with Chronic Lung Exposure to Coccidioides Fungal Arthroconidia

Links between repeated microbial infections and B cell chronic lymphocytic leukemia (B-CLL) have been proposed but not tested directly. This study examines how prolonged exposure to a human fungal pathogen impacts B-CLL development in Eµ-hTCL1-transgenic mice. Monthly lung exposure to inactivated Coccidioides arthroconidia, agents of Valley fever, altered leukemia development in a species-specific manner, with Coccidioides posadasii hastening B-CLL diagnosis/progression in a fraction of mice and Coccidioides immitis delaying aggressive B-CLL development, despite fostering more rapid monoclonal B cell lymphocytosis. Overall survival did not differ significantly between control and C. posadasii-treated cohorts but was significantly extended in C. immitis-exposed mice. In vivo doubling time analyses of pooled B-CLL showed no difference in growth rates of early and late leukemias. However, within C. immitis-treated mice, B-CLL manifests longer doubling times, as compared with B-CLL in control or C. posadasii-treated mice, and/or evidence of clonal contraction over time. Through linear regression, positive relationships were noted between circulating levels of CD5+/B220low B cells and hematopoietic cells previously linked to B-CLL growth, albeit in a cohort-specific manner. Neutrophils were positively linked to accelerated growth in mice exposed to either Coccidioides species, but not in control mice. Conversely, only C. posadasii-exposed and control cohorts displayed positive links between CD5+/B220low B cell frequency and abundance of M2 anti-inflammatory monocytes and T cells. The current study provides evidence that chronic lung exposure to fungal arthroconidia affects B-CLL development in a manner dependent on fungal genotype. Correlative studies suggest that fungal species differences in the modulation of nonleukemic hematopoietic cells are involved.

SOHO State of the Art Updates and Next Questions | Infections in Chronic Lymphocytic Leukemia Patients: Risks and Management

Although chronic lymphocytic leukemia (CLL) is a malignancy characterized by accumulation of tumor cells in the blood, bone marrow, lymph nodes and secondary lymphoid tissues, the hallmark of the disease and the major cause of death for patients with CLL is actually immune dysfunction and associated infections. Despite improvement in treatment based on combination chemoimmunotherapy and targeted treatment with BTK and BCL-2 inhibitors leading to longer overall survival for patients with CLL, the mortality due to infections have not improved over the last 4 decades. Thus, infections are now the main cause of death for patients with CLL, posing threats to the patient whether during the premalignant state of monoclonal B lymphocytosis (MBL), during the watch & wait phase for treatment naïve patients, or upon treatment in terms of chemoimmunotherapy or targeted treatment. To test whether the natural history of immune dysfunction and infections in CLL can be changed, we have developed the machine learning based algorithm CLL-TIM.org to identify these patients. The CLL-TIM algorithm is currently being used for selection of patients for the clinical trial PreVent-ACaLL (NCT03868722), testing whether short-term treatment with the BTK inhibitor acalabrutinib and the BCL-2 inhibitor venetoclax can improve immune function and decrease the risk of infections for this high-risk patient population. We here review the background for and management of infectious risks in CLL.

The Formation of NETs and Their Mechanism of Promoting Tumor Metastasis

Neutrophil extracellular traps (NETs) are network structures comprised of decondensed DNA strands coated with granule proteins. There have been three types of NETs recorded. NETs have been discovered concerning the progression of some malignancies, including gastric cancer, breast cancer, ovarian cancer, hepatocellular carcinoma, colorectal cancer, glioblastoma, diffuse large B cell lymphoma (DLBCL), and lung cancer, among others. In various methods, tumors encourage the formation of NETs, and NETs, in turn, promote tumor growth. NETs can stimulate primary tumor cell proliferation, suppress immune cells to create a tumor-friendly immune microenvironment, and stimulate epithelial-mesenchymal transition (EMT). NETs significantly promote liver and lung metastasis, possibly by altering vascular permeability, inducing cytoskeleton rearrangement and directional cell migration, and reawakening dormant cancer cells. NETs are therapeutically promising targets for cancer patients. Cancer patients may benefit from anti-NETs therapy, especially when combined with immune checkpoint inhibitors.

The Yin-Yang of myeloid cells in the leukemic microenvironment: Immunological role and clinical implications

The leukemic microenvironment has a high diversity of immune cells that are phenotypically and functionally distinct. However, our understanding of the biology, immunology, and clinical implications underlying these cells remains poorly investigated. Among the resident immune cells that can infiltrate the leukemic microenvironment are myeloid cells, which correspond to a heterogeneous cell group of the innate immune system. They encompass populations of neutrophils, macrophages, and myeloid-derived suppressor cells (MDSCs). These cells can be abundant in different tissues and, in the leukemic microenvironment, are associated with the clinical outcome of the patient, acting dichotomously to contribute to leukemic progression or stimulate antitumor immune responses. In this review, we detail the current evidence and the many mechanisms that indicate that the activation of different myeloid cell populations may contribute to immunosuppression, survival, or metastatic dissemination, as well as in immunosurveillance and stimulation of specific cytotoxic responses. Furthermore, we broadly discuss the interactions of tumor-associated neutrophils and macrophages (TANs and TAMs, respectively) and MDSCs in the leukemic microenvironment. Finally, we provide new perspectives on the potential of myeloid cell subpopulations as predictive biomarkers of therapeutical response, as well as potential targets in the chemoimmunotherapy of leukemias due to their dual Yin-Yang roles in leukemia.

The role of neutrophil extracellular traps in cancer progression, metastasis and therapy

Neutrophil extracellular traps (NETs) released by activated neutrophils typically consist of DNA-histone complexes and granule proteins. NETs were originally identified as a host defense system against foreign pathogens and are strongly associated with autoimmune diseases. However, a novel and predominant role of NETs in cancer is emerging. Increasing evidence has confirmed that many stimuli can facilitate NET formation in an NADPH oxidase (NOX)-dependent/NOX-independent manner. In cancer, NETs have been linked to cancer progression, metastasis, and cancer-associated thrombosis. In this review, we aimed to summarize the current available knowledge regarding NET formation and focused on the role of NETs in cancer biological behaviors. The potential target for cancer therapy will be further discussed.

Lenalidomide enhances CD23.CAR T cell therapy in chronic lymphocytic leukemia

Chimeric antigen receptors (CAR)-modified T cells are an emerging therapeutic tool for chronic lymphocytic leukemia (CLL). However, in patients with CLL, well-known T-cell defects and the inhibitory properties of the tumor microenvironment (TME) hinder the efficacy of CAR T cells. We explored a novel approach combining CARs with lenalidomide, an immunomodulatory drug that tempers the immunosuppressive activity of the CLL TME. T cells from patients with CLL were engineered to express a CAR specific for CD23, a promising target antigen. Lenalidomide maintained the in vitro effector functions of CD23.CAR⁺ T cells effector functions in terms of antigen-specific cytotoxicity, cytokine release and proliferation. Overall, lenalidomide preserved functional CAR T-CLL cell immune synapses. In a Rag2^-/-γ_c^-/--based xenograft model of CLL, we demonstrated that, when combined with low-dose lenalidomide, CD23.CAR⁺ T cells efficiently migrated to leukemic sites and delayed disease progression when compared to CD23.CAR⁺ T cells given with rhIL-2. These observations underline the therapeutic potential of this novel CAR-based combination strategy in CLL.

Management of Hematologic Malignancies in the Era of COVID-19 Pandemic: Pathogenetic Mechanisms, Impact of Obesity, Perspectives, and Challenges

The COVID-19 pandemic brought about an unprecedented societal and healthcare system crisis, considerably affecting healthcare workers and patients, particularly those with chronic diseases. Patients with hematologic malignancies faced a variety of challenges, pertinent to the nature of an underlying hematologic disorder itself as well as its therapy as a risk factor for severe SARS-CoV-2 infection, suboptimal vaccine efficacy and the need for uninterrupted medical observation and continued therapy. Obesity constitutes another factor which was acknowledged since the early days of the pandemic that predisposed people to severe COVID-19, and shares a likely causal link with the pathogenesis of a broad spectrum of hematologic cancers. We review here the epidemiologic and pathogenetic features that obesity and hematologic malignancies share, as well as potential mutual pathophysiological links predisposing people to a more severe SARS-CoV-2 course. Additionally, we attempt to present the existing evidence on the multi-faceted crucial challenges that had to be overcome in this diverse patient group and discuss further unresolved questions and future challenges for the management of hematologic malignancies in the era of COVID-19.

Extracellular Traps Increase Burden of Bleeding by Damaging Endothelial Cell in Acute Promyelocytic Leukaemia

The rate of complete remission of acute promyelocytic leukemia (APL) is currently over 90% because of the use of all-trans retinoic acid (ATRA) with arsenic trioxide (ATO). However, hemorrhagic mortality has emerged as the most significant barrier to APL-induced remission. Neutrophils extracellular traps (NETs/ETs) cause vascular leakage by damaging the integrity of endothelial cells. We have previously demonstrated that APL cells treated with ATRA/ATO undergo a cell death process, releasing extracellular chromatin, termed ETosis/NETosis. However, the mechanism underlying the involvement of ETs in endothelial injury in APL remain largely unknown. Here, we analysed the ability of mature and immature neutrophils to release ETs, and their interaction with platelets (PLTs) in APL. Importantly, the effect of ETs on vascular endothelium in APL was discussed. Our results showed that the ability of immature neutrophils to release ETs was impaired in APL, whereas mature neutrophils produced ETs, which were associated with activated PLTs. Moreover, ATRA+ATO induced immature neutrophil differentiation, as well as increased the release of ETs from mature neutrophils. The excessive ETs damaged endothelial cells, causing blood cell leakage. Removing ETs using DNase 1 alleviated endothelial damage and improved blood cells leakage. Our results indicate that vascular endothelial injury is at least partially associated with ETs in APL, and that targeting ETs production may be an effective approach for relieving vascular leakage and reducing the burden of bleeding in APL.

The Role of Neutrophils in the Pathogenesis of Chronic Lymphocytic Leukemia

Tumor-associated neutrophils appear to be a crucial element of the tumor microenvironment that actively participates in the development and progression of cancerous diseases. The increased lifespan, plasticity in changing of phenotype, and functions of neutrophils influence the course of the disease and may significantly affect survival. In patients with chronic lymphocytic leukemia (CLL), disturbances in neutrophils functions impede the effective immune defense against pathogens. Therefore, understanding the mechanism underlying such a phenomenon in CLL seems to be of great importance. Here we discuss the recent reports analyzing the phenotype and functions of neutrophils in CLL, the most common leukemia in adults. We summarize the data concerning both the phenotype and the mechanisms by which neutrophils directly support the proliferation and survival of malignant B cells.

Neutrophil Extracellular Traps in Digestive Cancers: Warrior or Accomplice

Characterized as a complex of extracellular DNA fibers and granule proteins, neutrophil extracellular traps (NETs) are generated specifically by neutrophils which play a critical role in host defense and immune regulation. NETs have been initially found crucial for neutrophil anti-microbial function. Recent studies suggest that NETs are involved in tumorigenesis and cancer progression. However, the function of NETs in cancer remains unclear, which might be due to the variation of research models and the heterogeneity of cancers. Although most of malignant tumors have similar biological behaviors, significant differences indeed exist in various systems. Malignant tumors of the digestive system cause the most incidence and mortality of cancer worldwide. In this review, we would focus on research developments on NETs in digestive cancers to provide insights on their role in digestive cancer progression and future research directions.

The regulatory mechanism of neutrophil extracellular traps in cancer biological behavior

As the predominant host defense against pathogens, neutrophil extracellular traps (NETs) have attracted increasing attention due to their vital roles in infectious inflammation in the past few years. Interestingly, NETs also play important roles in noninfectious conditions, such as rheumatism and cancer. The process of NETs formation can be regulated and the form of cell death accompanied by the formation of NETs is regarded as "NETosis". A large amount of evidence has confirmed that many stimuli can facilitate the release of NETs from neutrophils. Furthermore, it has been illustrated that NETs promote tumor growth and progression via many molecular pathways. Meanwhile, NETs also can promote metastasis in many kinds of cancers based on multiple studies. In addition, some researchs have found that NETs can promote coagulation and cancer-associated thrombosis. In the present review, it will highlight how NETosis, which is stimulated by various stimuli and signaling pathways, affects cancer biological behaviors via NETs. Given their crucial roles in cancer, NETs will become possible therapeutic targets for inhibiting proliferation, metastasis and thrombosis in cancer patients.

Secondary Immunodeficiency in Hematological Malignancies: Focus on Multiple Myeloma and Chronic Lymphocytic Leukemia

Secondary immunodeficiency is reported in most patients with hematological malignancies such as chronic lymphocytic leukemia and multiple myeloma. The aim of our review was to evaluate the existing literature data on patients with hematological malignancies, with regard to the effect of immunodeficiency on the outcome, the clinical and therapeutic approach, and on the onset of noninfectious complications, including thrombosis, pleural effusion, and orofacial complications. Immunodeficiency in these patients has an intense impact on their risk of infection, in turn increasing morbidity and mortality even years after treatment completion. However, these patients with increased risk of severe infectious diseases could be treated with adequate vaccination coverage, but the vaccines' administration can be associated with a decreased immune response and an augmented risk of adverse reactions. Probably, immunogenicity of the inactivated is analogous to that of healthy subjects at the moment of vaccination, but it undertakes a gradual weakening over time. However, the dispensation of live attenuated viral vaccines is controversial because of the risk of the activation of vaccine viruses. A particular immunization schedule should be employed according to the clinical and immunological condition of each of these patients to guarantee a constant immune response without any risks to the patients' health.

Hexavalent chromium inhibits the formation of neutrophil extracellular traps and promotes the apoptosis of neutrophils via AMPK signaling pathway

As the most common heavy metal pollutant, hexavalent chromium [Cr(VI)] has caused serious environmental pollution and health damage. Although the toxic effect of Cr(VI) has been widely studied, and oxidative stress has been confirmed to be the main mechanism of its cytotoxicity, the toxicity of Cr(VI) to human immune system remains to be elucidated. Neutrophil extracellular traps (NETs) participate in the innate immune response, and the release of NETs is considered to be the most important part of the extracellular killing mechanism. We demonstrated in this study that Cr(VI) inhibited the formation of NETs in rat peripheral blood and induced neutrophils apoptosis by inhibiting the AMP-activated protein kinase (AMPK) signaling pathway. Cr(VI)-induced inhibition of NETs was accompanied by down-regulated myeloperoxidase (MPO)/Histones-3 (H3) protein expressions and decreased NETs-associated intracellular and extracellular DNA levels in the neutrophils. Metformin (Met), as an AMPK activator, triggered autophagy and thus alleviated the inhibitory effect of Cr(VI) on NETs. At the same time, Met can reduce the intracellular reactive oxygen species (ROS) level by activating the AMPK/nuclear factor erythroid-2 related factor 2 (Nrf2) signaling pathway, thus alleviating Cr(VI)-induced neutrophils apoptosis. In conclusion, this study elucidated the mechanism of Cr(VI)-induced neutrophils toxicity and the role of AMPK as a key regulatory signal, which could provide valuable experimental basis for the prevention and treatment of related diseases in Cr(VI)-exposed populations.

Neutrophils in Tumorigenesis: Missing Targets for Successful Next Generation Cancer Therapies?

Neutrophils—once considered as simple killers of pathogens and unexciting for cancer research—are now acknowledged for their role in the process of tumorigenesis. Neutrophils are recruited to the tumor microenvironment where they turn into tumor-associated neutrophils (TANs), and are able to initiate and promote tumor progression and metastasis. Conversely, anti-tumorigenic properties of neutrophils have been documented, highlighting the versatile nature and high pleiotropic plasticity of these polymorphonuclear leukocytes (PMN-L). Here, we dissect the ambivalent roles of TANs in cancer and focus on selected functional aspects that could be therapeutic targets. Indeed, the critical point of targeting TAN functions lies in the fact that an immunosuppressive state could be induced, resulting in unwanted side effects. A deeper knowledge of the mechanisms linked to diverse TAN functions in different cancer types is necessary to define appropriate therapeutic strategies that are able to induce and maintain an anti-tumor microenvironment.

Proteomic and bioinformatic profiling of neutrophils in CLL reveals functional defects that predispose to bacterial infections

Patients with chronic lymphocytic leukemia (CLL) typically suffer from frequent and severe bacterial infections. Although it is well known that neutrophils are critical innate immune cells facilitating the early defense, the underlying phenotypical and functional changes in neutrophils during CLL remain largely elusive. Using a murine adoptive transfer model of CLL, we demonstrate aggravated bacterial burden in CLL-bearing mice upon a urinary tract infection with uropathogenic Escherichia coli. Bioinformatic analyses of the neutrophil proteome revealed increased expression of proteins associated with interferon signaling and decreased protein expression associated with granule composition and neutrophil migration. Functional experiments validated these findings by showing reduced levels of myeloperoxidase and acidification of neutrophil granules after ex vivo phagocytosis of bacteria. Pathway enrichment analysis indicated decreased expression of molecules critical for neutrophil recruitment, and migration of neutrophils into the infected urinary bladder was significantly reduced. These altered migratory properties of neutrophils were also associated with reduced expression of CD62L and CXCR4 and correlated with an increased incidence of infections in patients with CLL. In conclusion, this study describes a molecular signature of neutrophils through proteomic, bioinformatic, and functional analyses that are linked to a reduced migratory ability, potentially leading to increased bacterial infections in patients with CLL.

Circulating Nucleosomes as Potential Markers to Monitor COVID-19 Disease Progression

The severity of coronavirus disease 2019 (COVID-19) varies significantly with cases spanning from asymptomatic to lethal with a subset of individuals developing Severe Acute Respiratory Syndrome (SARS) and death from respiratory failure. To determine whether global nucleosome and citrullinated nucleosome levels were elevated in COVID-19 patients, we tested two independent cohorts of COVID-19 positive patients with quantitative nucleosome immunoassays and found that nucleosomes were highly elevated in plasma of COVID-19 patients with a severe course of the disease relative to healthy controls and that both histone 3.1 variant and citrullinated nucleosomes increase with disease severity. Elevated citrullination of circulating nucleosomes is indicative of neutrophil extracellular trap formation, neutrophil activation and NETosis in severely affected individuals. Importantly, using hospital setting (outpatient, inpatient or ICU) as a proxy for disease severity, nucleosome levels increased with disease severity and may serve as a guiding biomarker for treatment. Owing to the limited availability of mechanical ventilators and extracorporal membrane oxygenation (ECMO) equipment, there is an urgent need for effective tools to rapidly assess disease severity and guide treatment selection. Based on our studies of two independent cohorts of COVID-19 patients from Belgium and Germany, we suggest further investigation of circulating nucleosomes and citrullination as biomarkers for clinical triage, treatment allocation and clinical drug discovery.

Common and Rare Variants Genetic Association Analysis of Circulating Neutrophil Extracellular Traps

Introduction

Neutrophils contribute to host defense through different mechanisms, including the formation of neutrophil extracellular traps (NETs). The genetic background and underlying mechanisms contributing to NET formation remain unclear.

Materials and Methods

We performed a genome-wide association study (GWAS) and exome-sequencing analysis to identify common and rare genetic variants associated with plasma myeloperoxidase (MPO)-DNA complex levels, a biomarker for NETs, in the population-based Rotterdam Study cohort. GWAS was performed using haplotype reference consortium(HRC)-imputed genotypes of common variants in 3,514 individuals from the first and 2,076 individuals from the second cohort of the Rotterdam Study. We additionally performed exome-sequencing analysis in 960 individuals to investigate rare variants in candidate genes.

Results

The GWAS yielded suggestive associations (p-value < 5.0 × 10^-6) of SNPs annotated to four genes. In the exome-sequencing analysis, a variant in TMPRSS13 gene was significantly associated with MPO-DNA complex levels (p-value < 3.06×10^-8). Moreover, gene-based analysis showed ten genes (OR10H1, RP11-461L13.5, RP11-24B19.4, RP11-461L13.3, KHDRBS1, ZNF200, RP11-395I6.1, RP11-696P8.2, RGPD1, AC007036.5) to be associated with MPO-DNA complex levels (p-value between 4.48 × 10^-9 and 1.05 × 10^-6). Pathway analysis of the identified genes showed their involvement in cellular development, molecular transport, RNA trafficking, cell-to-cell signaling and interaction, cellular growth and proliferation. Cancer was the top disease linked to the NET-associated genes.

Conclusion

In this first GWAS and exome-sequencing analysis of NETs levels, we found several genes that were associated with NETs. The precise mechanism of how these genes may contribute to neutrophil function or the formation of NETs remains unclear and should be further investigated in experimental studies.

Dynamic Changes in the Ability to Release Neutrophil ExtraCellular Traps in the Course of Childhood Acute Leukemias

Acute leukemias, the most common cancers in children, are characterized by excessive proliferation of malignant progenitor cells. As a consequence of impaired blood cell production, leukemia patients are susceptible to infectious complications—a major cause of non-relapse mortality. Neutrophil extracellular traps (NETs) are involved in various pathologies, from autoimmunity to cancer. Although aberrant NETs formation may be partially responsible for immune defects observed in acute leukemia, still little is known on the NET release in the course of leukemia. Here, we present the first comprehensive evaluation of NETs formation by neutrophils isolated from children with acute leukemia in different stages of the disease and treatment stimulated in vitro with phorbol 12-myristate 13-acetate (PMA), N-formyl-methionyl-leucyl-phenylalanine (fMLP), and calcium ionophore (CI). NETs release was measured using quantitative fluorescent method and visualized microscopically. In this setting, NETs release was significantly impaired in leukemic children both at the diagnosis and during the treatment, and full restoration of neutrophil function was achieved only after successful completion of the leukemia treatment. We suggest that neutrophil function impairment may result from both disease- and treatment-related factors. In this context, deficient innate immune response observed in acute leukemia patients may be present regardless of neutrophil count and contribute to secondary immunodeficiency observed in this population.

The effect of ibrutinib on neutrophil and γδ T cell functions

Ibrutinib is a BTK/ITK inhibitor with efficacy for the treatment of various lymphoid cancers, including CLL. Considering that innate and adaptative immune defects are a dominant feature of CLL patients, we evaluated whether in vitro ibrutinib affects the survival and function of neutrophils and γδ T cells, key players of the early immune response against microbes. Neutrophils and γδ T cells were obtained from peripheral blood of healthy donors and CLL patients. We found that ibrutinib reduces the production of reactive oxygen species (ROS) and bacteria killing capacity, and slightly impairs neutrophil extracellular traps (NETs) production without affecting bacteria-uptake and CD62L-downregulation induced by fMLP or aggregated IgG. In addition, ibrutinib reduces γδ T cell activation and CD107a degranulation induced by phosphoantigens or anti-CD3. These findings are in agreement with previous data suggesting that ibrutinib interferes with the protective immune response to pathogens, particularly Mycobacteria and Aspergillus.

Clinico-Biological Implications of Modified Levels of Cytokines in Chronic Lymphocytic Leukemia: A Possible Therapeutic Role

B-cell chronic lymphocytic leukemia (B-CLL) is the main cause of mortality among hematologic diseases in Western nations. B-CLL is correlated with an intense alteration of the immune system. The altered functions of innate immune elements and adaptive immune factors are interconnected in B-CLL and are decisive for its onset, evolution, and therapeutic response. Modifications in the cytokine balance could support the growth of the leukemic clone via a modulation of cellular proliferation and apoptosis, as some cytokines have been reported to be able to affect the life of B-CLL cells in vivo. In this review, we will examine the role played by cytokines in the cellular dynamics of B-CLL patients, interpret the contradictions sometimes present in the literature regarding their action, and evaluate the possibility of manipulating their production in order to intervene in the natural history of the disease.

Neutrophil traps, anti-myeloperoxidase antibodies and cancer: Are they linked?

Myeloperoxidase is an enzyme present in neutrophils and has been demonstrated to be an important molecule for neutrophil extracellular traps (NETs) formation and function. Yet, it is also a source of autoantigens for anti-neutrophil or anti-myeloperoxidase antibodies (ANCAs), which are capable of activating these immune cells and provoke tissue damage in a sterile microenvironment. The presence of these antibodies in cancer has been related by case reports, but a few studies addressed the significance of this finding beyond autoimmunity context. In this review, we discuss the evidences regarding ANCAs and cancer and its putative clinical meaning in the context of tumor immunology.

Immunoregulatory effects of Lurbinectedin in chronic lymphocytic leukemia

Despite significant therapeutic improvements chronic lymphocytic leukemia (CLL) remains an incurable disease and there is a persistent pursuit of new treatment alternatives. Lurbinectedin, a selective inhibitor of active transcription of protein-coding genes, is currently in phase II/III clinical trials for solid tumors such as small-cell lung cancer (SCLC). In this study, we aimed to evaluate the activity of Lurbinectedin on circulating mononuclear cells from CLL patients and to determine whether Lurbinectedin could affect the cross-talk between B-CLL cells and the tumor microenvironment. We found that Lurbinectedin induced a dose- and time-dependent death in all cell types evaluated, with B cells, monocytes and monocytic myeloid derived suppressor cells (Mo-MDSC) being the most susceptible populations. At sub-apoptotic doses, Lurbinectedin decreased the expression of CCR7 in B-CLL cells and impaired their migration towards CCL19 and CCL21. Furthermore, low concentrations of Lurbinectedin stimulated the synthesis of pro-IL1β in monocytes and nurse-like cells, without inducing the inflammasome activation. Altogether, these results indicate that Lurbinectedin might have antitumor activity in CLL due to its direct action on leukemic cells in combination with its effects on the tumor microenvironment. Our findings encourage further investigation of Lurbinectedin as a potential therapy for CLL.

Chemokine CXCb1 stimulates formation of NETs in trunk kidney neutrophils of common carp

Both in mammals and in fish, CXC chemokines activate leukocytes and regulate their migration both under normal physiological and inflammatory conditions. Moreover, in mammalian neutrophils CXC chemokines also stimulate the formation of neutrophil extracellular traps (NETs). Here, we investigated the effects of recombinant carp CXCL8s and CXCb1 on NET formation in neutrophils from the head (HK) and trunk (TK) kidney of carp. We found that neither recombinant CXCL8s nor CXCb1 stimulated DNA release in HK-derived neutrophils, while in TK-derived cells rcCXCb1 stimulated the release of NETs, composed of extracellular DNA co-localized with citrulline H3 histone and neutrophil elastase. Furthermore, CXCb1-induced NET release required NADPH oxidase activity, while it did not change upon treatment with CXCR inhibitors. In conclusion, we demonstrated, for the first time in fish, that CXCb1 chemokine induces formation of NETs in TK-derived neutrophils and this process is ROS-dependent. The difference between HK and TK-derived neutrophils is probably related to differences in the maturation state of these cells.

Thrombin Generation and Cancer: Contributors and Consequences

The high occurrence of cancer-associated thrombosis is associated with elevated thrombin generation. Tumour cells increase the potential for thrombin generation both directly, through the expression and release of procoagulant factors, and indirectly, through signals that activate other cell types (including platelets, leukocytes and erythrocytes). Furthermore, cancer treatments can worsen these effects. Coagulation factors, including tissue factor, and inhibitors of coagulation are altered and extracellular vesicles (EVs), which can promote and support thrombin generation, are released by tumour and other cells. Some phosphatidylserine-expressing platelet subsets and platelet-derived EVs provide the surface required for the assembly of coagulation factors essential for thrombin generation in vivo. This review will explore the causes of increased thrombin production in cancer, and the availability and utility of tests and biomarkers. Increased thrombin production not only increases blood coagulation, but also promotes tumour growth and metastasis and as a consequence, thrombin and its contributors present opportunities for treatment of cancer-associated thrombosis and cancer itself.

Chronic lymphocytic leukemia cells increase neutrophils survival and promote their differentiation into CD16high CD62Ldim immunosuppressive subset

Reprogramming of neutrophils by malignant cells is well-described for many types of solid tumors, but data remain scarce for hematological diseases. Chronic lymphocytic leukemia (CLL) is characterized for a deep immune dysregulation mediated by leukemic cells that compromises patient's outcome. Murine models of CLL highlight the relevance of myeloid cells as tumor-driven reprogramming targets. In our study, we evaluated neutrophil reprogramming by CLL cells. We first show that the proportion of the CD16^high CD62L^dim neutrophil subset in peripheral blood of CLL patients is increased compared to age-matched healthy donors (HD). In vitro, neutrophils from HD cultured in the presence of CLL cells or conditioned media (CM) from CLL cells exhibited a longer lifespan. Depletion of G-CSF and GM-CSF from CM partially reversed the protective effect. In addition, the proportion of viable neutrophils that displayed a CD16^high CD62L^dim phenotype was increased in the presence of CM from CLL cells, being TGF-β/IL-10 responsible for this effect. Altogether, our results describe a novel mechanism through which CLL cells can manipulate neutrophils.

Peptidylarginine deiminase 4: a nuclear button triggering neutrophil extracellular traps in inflammatory diseases and aging

Peptidylarginine deiminase 4 (PAD4) is a nuclear citrullinating enzyme that is critically involved in the release of decondensed chromatin from neutrophils as neutrophil extracellular traps (NETs). NETs, together with fibrin, are implicated in host defense against pathogens; however, the formation of NETs (NETosis) has injurious effects that may outweigh their protective role. For example, PAD4 activity produces citrullinated neoantigens that promote autoimmune diseases, such as rheumatoid arthritis, to which PAD4 is genetically linked and where NETosis is prominent. NETs are also generated in basic sterile inflammatory responses that are induced by many inflammatory stimuli, including cytokines, hypoxia, and activated platelets. Mice that lack PAD4-deficient in NETosis-serve as an excellent tool with which to study the importance of NETs in disease models. In recent years, animal and human studies have demonstrated that NETs contribute to the etiology and propagation of many common noninfectious diseases, the focus of our review. We will discuss the role of NETs in thrombotic and cardiovascular disease, the induction of NETs by cancers and its implications for cancer progression and cancer-associated thrombosis, and elevated NETosis in diabetes and its negative impact on wound healing, and will propose a link between PAD4/NETs and age-related organ fibrosis. We identify unresolved issues and new research directions.-Wong, S. L., Wagner, D. D. Peptidylarginine deiminase 4: a nuclear button triggering neutrophil extracellular traps in inflammatory diseases and aging.

Reduced Neutrophil Elastase Activity and Neutrophil Extracellular Traps in Pediatric Acute Myeloid Leukemia May Increase the Rate of Infections

Data on the production of neutrophil extracellular traps (NETs) in leukemia patients are scant. Phagocytosis, hydrogen peroxide, neutrophil elastase and myeloperoxidase enzymatic activity as well as NETs formation were studied in 10 pediatric acute lymphoblastic leukemia and 7 pediatric acute myeloid leukemia (AML) patients after induction chemotherapy. Median neutrophil elastase activity and NETs formation were lower in AML versus acute lymphoblastic leukemia (41% vs. 90%, P=0.005 and 51% vs. 94%, P=0.008, respectively). AML patients had more episodes of febrile neutropenia during the first 2 blocks of treatment (100% vs. 40%, P=0.011) and a trend for more invasive bacterial and fungal infections.

Citrullinated histone H3 as a novel prognostic blood marker in patients with advanced cancer

Citrullinated histone H3 (H3Cit) is a central player in the neutrophil release of nuclear chromatin, known as neutrophil extracellular traps (NETs). NETs have been shown to elicit harmful effects on the host, and were recently proposed to promote tumor progression and spread. Here we report significant elevations of plasma H3Cit in patients with advanced cancer compared with age-matched healthy individuals. These elevations were specific to cancer patients as no increase was observed in severely ill and hospitalized patients with a higher non-malignant comorbidity. The analysis of neutrophils from cancer patients showed a higher proportion of neutrophils positive for intracellular H3Cit compared to severely ill patients. Moreover, the presence of plasma H3Cit in cancer patients strongly correlated with neutrophil activation markers neutrophil elastase (NE) and myeloperoxidase (MPO), and the inflammatory cytokines interleukin-6 and -8, known to induce NETosis. In addition, we show that high levels of circulating H3Cit strongly predicted poor clinical outcome in our cohort of cancer patients with a 2-fold increased risk for short-term mortality. Our results also corroborate the association of NE, interleukin-6 and -8 with poor clinical outcome. Taken together, our results are the first to unveil H3Cit as a potential diagnostic and prognostic blood marker associated with an exacerbated inflammatory response in patients with advanced cancer.

Revisiting the role of interleukin-8 in chronic lymphocytic leukemia

The proliferation and survival of malignant B cells in chronic lymphocytic leukemia (CLL) depend on signals from the microenvironment in lymphoid tissues. Among a plethora of soluble factors, IL-8 has been considered one of the most relevant to support CLL B cell progression in an autocrine fashion, even though the expression of IL-8 receptors, CXCR1 and CXCR2, on leukemic B cells has not been reported. Here we show that circulating CLL B cells neither express CXCR1 or CXCR2 nor they respond to exogenous IL-8 when cultured in vitro alone or in the presence of monocytes/nurse-like cells. By intracellular staining and ELISA we show that highly purified CLL B cells do not produce IL-8 spontaneously or upon activation through the B cell receptor. By contrast, we found that a minor proportion (<0.5%) of contaminating monocytes in enriched suspensions of leukemic cells might be the actual source of IL-8 due to their strong capacity to release this cytokine. Altogether our results indicate that CLL B cells are not able to secrete or respond to IL-8 and highlight the importance of methodological details in in vitro experiments.

Multiple Phenotypic Changes Define Neutrophil Priming

Exposure to pro-inflammatory cytokines, chemokines, mitochondrial contents, and bacterial and viral products induces neutrophils to transition from a basal state into a primed one, which is currently defined as an enhanced response to activating stimuli. Although, typically associated with enhanced generation of reactive oxygen species (ROS) by the NADPH oxidase, primed neutrophils show enhanced responsiveness of exocytosis, NET formation, and chemotaxis. Phenotypic changes associated with priming also include activation of a subset of functions, including adhesion, transcription, metabolism, and rate of apoptosis. This review summarizes the breadth of phenotypic changes associated with priming and reviews current knowledge of the molecular mechanisms behind those changes. We conclude that the current definition of priming is too restrictive. Priming represents a combination of enhanced responsiveness and activated functions that regulate both adaptive and innate immune responses.