Markers of neutrophil activation and neutrophil extracellular traps in diagnosing patients with acute venous thromboembolism: A feasibility study based on two VTE cohorts

Serum MPO-DNA for Predicting the Risk of Venous Thromboembolism and the Effect of Statins in Patients with Spontaneous Intracerebral Hemorrhage

Patients with spontaneous intracerebral hemorrhage (ICH) are at high risk of venous thromboembolism (VTE). Recent studies have shown the involvement of neutrophil extracellular traps (NETs) in thrombogenesis.To explore the predictive value of serum MPO-DNA (a NETs surrogate) for VTE and the effect of statins on serum MPO-DNA levels and the VTE incidence in ICH patients.This prospective cohort study enrolled 117 ICH patients and 15 healthy controls. Serum MPO-DNA levels were measured via ELISA. The relationship between serum MPO-DNA levels and VTE risk was analyzed. The predictive value of MPO-DNA was evaluated by ROC curves. Effects of statin on NETs and VTE incidence were evaluated.The median MPO-DNA level in patients with VTE was 0.304 (95% CI: 0.231-0.349), significantly higher than the 0.188 (95% CI: 0.159-0.236) in non-VTE patients. Elevated MPO-DNA levels were associated with an increased VTE risk (OR 7.13, 95% CI 2.58-19.75; P < 0.001), and this association persisted after adjustment. The AUC values for MPO-DNA, CRP, and D-dimer were 0.824 (95% CI: 0.719-0.928), 0.618 (95% CI: 0.481-0.754), and 0.786 (95% CI: 0.683-0.888), respectively. Moreover, statin users exhibited reduced MPO-DNA levels (0.174 vs. 0.218; P = 0.007), though VTE incidence differences (13.8% vs. 19.3%) lacked statistical significance.Serum MPO-DNA serves as a sensitive biomarker for VTE prediction in ICH, highlighting NETs as potential therapeutic targets. Statins could attenuate NETosis, but larger trials are required to validate their clinical efficacy and safety in VTE prevention for ICH patients.

Risk factors and a risk assessment model for venous thromboembolism in head and neck cancer surgery

OBJECTIVES

Although various associations between venous thromboembolism (VTE) and head and neck cancer have been identified, limited data exist regarding the incidence of VTE in patients undergoing surgery for head and neck cancer. This study aims to investigate potential risk factors for VTE development in head and neck cancer patients and establish a risk assessment model to aid in risk stratification for these individuals.

METHODS

The Cox proportional hazards model, including univariable and multivariable analyses, was used to assess potentially significant risk factors. The competing risk model was employed for validation in the analysis of VTE events.

RESULTS

Among the 1,122 patients who underwent surgery for head and neck cancer, the incidence of VTE was found to be 2.3 %, with a mortality rate of 0.4 %. Significantly associated factors for VTE development included older age, smoking, hyperlipidemia, pulmonary disease, high neutrophils, low hemoglobin, high D-Dimer, and operation time > 3 h. Using the VTE risk assessment model for patients undergoing head and neck cancer surgery, the subdistribution hazard risk for VTE development was determined to be 8.96-fold (95 % CI, 1.03-98.19) (P = 0.047) for low-risk patients and 27.47-fold (95 % CI, 3.32-184.54) (P = 0.001) for high-risk patients.

CONCLUSION

The proposed risk assessment model may guide clinicians in stratifying VTE risk and implementing targeted prophylactic measures in head and neck cancer surgery patients.

Advanced Research in the Pathophysiology of Venous Thromboembolism-Acute Pulmonary Embolism

According to the literature, cardiovascular diseases (CVDs)-including myocardial infarction, stroke, and venous thromboembolism (VTE)-are among the leading causes of mortality and morbidity worldwide. Evidence suggests that CVDs share common risk factors and pathophysiological mechanisms. Similar to the Mosaic Theory of Hypertension proposed by Irvine Page in 1949, the pathophysiology of VTE is multifactorial, involving multiple interacting processes. The concept of immunothrombosis, introduced by Engelmann and Massberg in 2009, describes the interplay between the immune system and thrombosis. Both thrombosis and hemostasis share core mechanisms, including platelet activation and fibrin formation. Additionally, immune mediators-such as monocytes, neutrophil extracellular traps (NETs), lymphocytes, selectins, and various molecular factors-play a critical role in thrombus formation. This review highlights inflammation as a key risk factor for pulmonary embolism (APE). Immunity is central to the complex interactions among the coagulation cascade, platelets, endothelium, reactive oxygen species (ROS), and genetic factors. Specifically, we examine the roles of the endothelium, immune cells, and microRNAs (miRNAs) in the pathophysiology of APE and explore potential therapeutic targets. This review aims to elucidate the roles of the endothelium, immune cells, and miRNAs in the pathophysiology of APE and explore potential future perspective.

Therapeutic potential of DNases in immunothrombosis: promising succor or uncertain future?

Sepsis, a life-threatening condition characterized by systemic inflammation and multiorgan dysfunction, is closely associated with the excessive formation of neutrophil extracellular traps (NETs) and the release of cell-free DNA. Both play a central role in sepsis progression, acting as major contributors to immunothrombosis and associated complications. Endogenous DNases play a pivotal role in degrading NETs and cell-free DNA, yet their activity is often dysregulated during thrombotic disease. Although exogenous DNase1 administration has shown potential in reducing NET burden and mitigating the detrimental effects of immunothrombosis, its therapeutic efficacy upon intravenous administration remains uncertain. The development of engineered DNase formulations and combination therapies may further enhance its therapeutic effectiveness by modifying its pharmacodynamic properties and avoiding the adverse effects associated with NET degradation, respectively. Although NETs are well-established targets of DNase1, it remains uncertain whether the positive effects of DNase1 on immunothrombosis are exclusively related to it's targeting of NETs or if other components contributing to immunothrombosis are also affected. This review examines the endogenous regulation of NETs in circulation and the therapeutic potential of DNases in immunothrombosis, underscoring the necessity for further investigation to optimize their clinical application.

HSYA ameliorates venous thromboembolism by depleting the formation of TLR4/NF-κB pathway-dependent neutrophil extracellular traps

Neutrophil extracellular traps (NETs), released by activated neutrophils, are implicated in various medical conditions, including venous thromboembolism (VTE). To develop effective therapeutic strategies for VTE, it is crucial to elucidate the mechanisms involved. In this study, we explored the role of NETs in VTE pathogenesis and assessed the impact of hydroxyl safflower yellow pigment A (HSYA) treatment on VTE pathogenesis. Various biochemical, pharmacological, and functional assessments were performed in human samples and VTE mouse models. Our findings revealed that NETs formation was enhanced in VTE patients and mouse model. NETs were shown to reduce the viability and integrity of endothelial cells and facilitated ferroptosis in human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. Depletion of NETs using the NE inhibitor Alvelestat significantly alleviated ferroptosis in VTE mice. Similarly, NETs depletion markedly attenuated thrombus formation and vein wall thickness in VTE mice. Notably, NETs treatment induced a significant elevation in total N6-Methyladenosine (m6A) RNA methylation level in HUVECs, with the most significant increase observed in methyltransferase-like 3 (METTL3). Mechanistically, the TLR4/NF-κB pathway was activated, and silencing METTL3 reversed the NETs-induced activation of this pathway in HUVECs. Rescue assays illustrated that METTL3 regulated the viability and ferroptosis of NETs-stimulated HUVECs by mediating TLR4 mRNA stability. Additionally, we found that HSYA exerted protective effects against ferroptosis in NETs-induced HUVECs and VTE mice. In summary, HSYA ameliorates VTE by depleting neutrophil extracellular traps through the inhibition of the TLR4/NF-κB pathway, thus providing a novel therapeutic strategy for treating VTE.

Neutrophil extracellular traps in homeostasis and disease

Neutrophil extracellular traps (NETs), crucial in immune defense mechanisms, are renowned for their propensity to expel decondensed chromatin embedded with inflammatory proteins. Our comprehension of NETs in pathogen clearance, immune regulation and disease pathogenesis, has grown significantly in recent years. NETs are not only pivotal in the context of infections but also exhibit significant involvement in sterile inflammation. Evidence suggests that excessive accumulation of NETs can result in vessel occlusion, tissue damage, and prolonged inflammatory responses, thereby contributing to the progression and exacerbation of various pathological states. Nevertheless, NETs exhibit dual functionalities in certain pathological contexts. While NETs may act as autoantigens, aggregated NET complexes can function as inflammatory mediators by degrading proinflammatory cytokines and chemokines. The delineation of molecules and signaling pathways governing NET formation aids in refining our appreciation of NETs' role in immune homeostasis, inflammation, autoimmune diseases, metabolic dysregulation, and cancer. In this comprehensive review, we delve into the multifaceted roles of NETs in both homeostasis and disease, whilst discussing their potential as therapeutic targets. Our aim is to enhance the understanding of the intricate functions of NETs across the spectrum from physiology to pathology.

Oxidative stress in acute pulmonary embolism: emerging roles and therapeutic implications

Oxidative stress is an imbalance between the body's reactive oxygen species and antioxidant defense mechanisms. Oxidative stress is involved in the development of several cardiovascular diseases, such as pulmonary hypertension, atherosclerosis, and diabetes mellitus. A growing number of studies have suggested the potential role of oxidative stress in the pathogenesis of pulmonary embolism. Biomarkers of oxidative stress in pulmonary embolism have also been explored, such as matrix metalloproteinases, asymmetric dimethylarginine, and neutrophil/lymphocyte ratio. Here, we comprehensively summarize some oxidative stress mechanisms and biomarkers in the development of acute pulmonary embolism and summarize related treatments based on antioxidant stress to explore effective treatment strategies for acute pulmonary embolism.

Neutrophil extracellular trap formation is an independent risk factor for occult cancer in patients presenting with venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE), particularly unprovoked VTE, is associated with occult cancer. The optimal screening regimen remains controversial. Neutrophil extracellular traps (NETs) are implicated in cancer-associated thrombosis, and elevated biomarkers of NET formation are associated with poor prognosis.

OBJECTIVES

To investigate the association between NET formation and occult cancer in patients with VTE.

METHODS

Blood biomarkers associated with NETs and neutrophil activation (nucleosomal citrullinated histone H3 [H3Cit-DNA], cell-free DNA, and neutrophil elastase) were quantified in patients with VTE. The primary outcome was cancer diagnosed during a one-year follow-up.

RESULTS

This study included 460 patients with VTE, of which 221 (48%) had isolated deep vein thrombosis. Forty-three patients had active cancer at inclusion and were excluded from the primary analysis Cancer during follow-up was diagnosed in 29 of 417 (7.0%) patients. After adjustment for age and unprovoked VTE, the hazard ratio of cancer during follow-up per 500 ng/mL increase of H3Cit-DNA was 1.79 (95% CI, 1.03-3.10). Furthermore, patients with cancer-associated VTE (known active cancer or cancer diagnosed during follow-up) had higher levels of H3Cit-DNA than cancer-free patients with VTE after adjustment for age, hemoglobin, gender, chronic obstructive pulmonary disease, previous cancer, and start of anticoagulant treatment (odds ratio 2.06 per 500 ng/mL increase of H3Cit-DNA [95% CI, 1.35-3.13]).

CONCLUSIONS

H3Cit-DNA is an independent predictor for occult cancer in patients with VTE and elevated in cancer-associated VTE, suggesting that H3Cit-DNA is potentially a useful diagnostic marker for cancer in patients with VTE and that elevated NET formation is a hallmark of cancer-associated VTE.

New Therapeutic Targets for the Prevention and Treatment of Venous Thromboembolism With a Focus on Factor XI Inhibitors

FXI (factor XI) and FXII (factor XII) have emerged as targets for new anticoagulants that have the potential to be both more efficacious and safer than the currently available direct oral anticoagulants for the prevention and treatment of venous thromboembolism. In this review, we discuss the role of FXI and FXII in the pathogenesis of venous thromboembolism, explain why FXI is a better target, and explain why FXI inhibitors have potential advantages over currently available anticoagulants. Finally, we describe the FXI inhibitors under development and discuss their potential to address unmet needs in venous thromboembolism management.

Neutrophil extracellular traps mediate deep vein thrombosis: from mechanism to therapy

Deep venous thrombosis (DVT) is a part of venous thromboembolism (VTE) that clinically manifests as swelling and pain in the lower limbs. The most serious clinical complication of DVT is pulmonary embolism (PE), which has a high mortality rate. To date, its underlying mechanisms are not fully understood, and patients usually present with clinical symptoms only after the formation of the thrombus. Thus, it is essential to understand the underlying mechanisms of deep vein thrombosis for an early diagnosis and treatment of DVT. In recent years, many studies have concluded that Neutrophil Extracellular Traps (NETs) are closely associated with DVT. These are released by neutrophils and, in addition to trapping pathogens, can mediate the formation of deep vein thrombi, thereby blocking blood vessels and leading to the development of disease. Therefore, this paper describes the occurrence and development of NETs and discusses the mechanism of action of NETs on deep vein thrombosis. It aims to provide a direction for improved diagnosis and treatment of deep vein thrombosis in the near future.

Immobility-associated thromboprotection is conserved across mammalian species from bear to human

Venous thromboembolism (VTE) comprising deep venous thrombosis and pulmonary embolism is a major cause of morbidity and mortality. Short-term immobility-related conditions are a major risk factor for the development of VTE. Paradoxically, long-term immobilized free-ranging hibernating brown bears and paralyzed spinal cord injury (SCI) patients are protected from VTE. We aimed to identify mechanisms of immobility-associated VTE protection in a cross-species approach. Mass spectrometry-based proteomics revealed an antithrombotic signature in platelets of hibernating brown bears with heat shock protein 47 (HSP47) as the most substantially reduced protein. HSP47 down-regulation or ablation attenuated immune cell activation and neutrophil extracellular trap formation, contributing to thromboprotection in bears, SCI patients, and mice. This cross-species conserved platelet signature may give rise to antithrombotic therapeutics and prognostic markers beyond immobility-associated VTE.

Identifying Neutrophil Extracellular Traps (NETs) in Blood Samples Using Peripheral Smear Autoanalyzers

Neutrophil Extracellular Traps (NETs) are large neutrophil-derived structures composed of decondensed chromatin, cytosolic, and granule proteins. NETs play an important role in fighting infection, inflammation, thrombosis, and tumor progression processes, yet their fast and reliable identification has been challenging. Smudge cells (SCs) are a subcategory of white cells identified by CellaVision^®, a hematology autoanalyzer routinely used in clinical practice that uses digital imaging to generate "manual" differentials of peripheral blood smears. We hypothesize that a proportion of cells identified in the SC category by CellaVision^® Hematology Autoanalyzers are actually NETs. We demonstrate that NET-like SCs are not present in normal blood samples, nor are they an artifact of smear preparation. NET-like SCs stain positive for neutrophil markers such as myeloperoxidase, leukocyte alkaline phosphatase, and neutrophil elastase. On flow cytometry, cells from samples with high percent NET-like SCs that are positive for surface DNA are also positive for CD45, myeloperoxidase and markers of neutrophil activation and CD66b. Samples with NET-like SCs have a strong side fluorescent (SFL) signal on the white count and nucleated red cells (WNR) scattergram, representing cells with high nucleic acid content. When compared to patients with low percent SCs, those with a high percentage of SCs have a significantly higher incidence of documented bacterial and viral infections. The current methodology of NET identification is time-consuming, complicated, and cumbersome. In this study, we present data supporting identification of NETs by CellaVision^®, allowing for easy, fast, cost-effective, and high throughput identification of NETs that is available in real time and may serve as a positive marker for a bacterial or viral infections.

Biomarkers of cell damage, neutrophil and macrophage activation associated with in-hospital mortality in geriatric COVID-19 patients

BACKGROUND

The risk for symptomatic COVID-19 requiring hospitalization is higher in the older population. The course of the disease in hospitalised older patients may show significant variation, from mild to severe illness, ultimately leading to death in the most critical cases. The analysis of circulating biomolecules involved in mechanisms of inflammation, cell damage and innate immunity could lead to identify new biomarkers of COVID-19 severity, aimed to improve the clinical management of subjects at higher risk of severe outcomes. In a cohort of COVID-19 geriatric patients (n= 156) who required hospitalization we analysed, on-admission, a series of circulating biomarkers related to neutrophil activation (neutrophil elastase, LL-37), macrophage activation (sCD163) and cell damage (nuclear cfDNA, mithocondrial cfDNA and nuclear cfDNA integrity). The above reported biomarkers were tested for their association with in-hospital mortality and with clinical, inflammatory and routine hematological parameters. Aim of the study was to unravel prognostic parameters for risk stratification of COVID-19 patients.

RESULTS

Lower n-cfDNA integrity, higher neutrophil elastase and higher sCD163 levels were significantly associated with an increased risk of in-hospital decease. Median (IQR) values observed in discharged vs. deceased patients were: 0.50 (0.30-0.72) vs. 0.33 (0.22-0.62) for n-cfDNA integrity; 94.0 (47.7-154.0) ng/ml vs. 115.7 (84.2-212.7) ng/ml for neutrophil elastase; 614.0 (370.0-821.0) ng/ml vs. 787.0 (560.0-1304.0) ng/ml for sCD163. The analysis of survival curves in patients stratified for tertiles of each biomarker showed that patients with n-cfDNA integrity < 0.32 or sCD163 in the range 492-811 ng/ml had higher risk of in-hospital decease than, respectively, patients with higher n-cfDNA integrity or lower sCD163. These associations were further confirmed in multivariate models adjusted for age, sex and outcome-related clinical variables. In these models also high levels of neutrophil elastase (>150 ng/ml) appeared to be independent predictor of in-hospital death. An additional analysis of neutrophil elastase in patients stratified for n-cfDNA integrity levels was conducted to better describe the association of the studied parameters with the outcome.

CONCLUSIONS

On the whole, biomarkers of cell-free DNA integrity, neutrophil and macrophage activation might provide a valuable contribution to identify geriatric patients with high risk of COVID-19 in-hospital mortality.

Clinical significance of neutrophil extracellular traps biomarkers in thrombosis

Neutrophil extracellular traps (NETs) may be associated with the development of thrombosis. Experimental studies have confirmed the presence of NETs in thrombi specimens and potential role of NETs in the mechanisms of thrombosis. Clinical studies also have demonstrated significant changes in the levels of serum or plasma NETs biomarkers, such as citrullinated histones, myeloperoxidase, neutrophil elastase, nucleosomes, DNA, and their complexes in patients with thrombosis. This paper aims to comprehensively review the currently available evidence regarding the change in the levels of NETs biomarkers in patients with thrombosis, summarize the role of NETs and its biomarkers in the development and prognostic assessment of venous thromboembolism, coronary artery diseases, ischemic stroke, cancer-associated thromboembolism, and coronavirus disease 2019-associated thromboembolism, explore the potential therapeutic implications of NETs, and further discuss the shortcomings of existing NETs biomarkers in serum and plasma and their detection methods.