NETosis promotes cancer-associated arterial microthrombosis presenting as ischemic stroke with troponin elevation

Occult cancer in patients with unprovoked venous thromboembolism: A nested case-control study

OBJECTIVES

Detecting occult cancer in patients with unprovoked venous thromboembolism (VTE) remains a significant challenge. Our objective was to investigate the potential predictive role of coagulation-related biomarkers in the diagnosis of occult malignancies.

METHODS

We conducted a nested case-control study with a 1-year prospective cohort of 214 patients with unprovoked VTE, with a focus on identifying occult cancer. At the time of VTE diagnosis, we measured various biomarkers, including soluble P-selectin (sP-selectin), dimerized plasmin fragment D (D-dimer), platelets, leukocytes, hemoglobin, total extracellular vesicles (EVs), EVs expressing tissue factor on their surface (TF+EVs), and EVs expressing P-selectin on their surface (Psel+EVs) in all participants.

RESULTS

We observed statistically significant increased levels of sP-selectin (P = .015) in patients with occult cancer. Despite an increase in Psel+EVs, TF+EVs, D-dimer, and platelets within this group, however, no significant differences were found. When sP-selectin exceeded 62 ng/mL and D-dimer surpassed 10,000 µg/L, the diagnosis of occult cancer demonstrated a specificity of up to 91% (95% CI, 79.9%-96.7%).

CONCLUSIONS

The combination of sP-selectin and D-dimer can be a valuable biomarker in detecting occult cancer in patients with unprovoked VTE. Further research is necessary to ascertain whether easily measurable biomarkers such as sP-selectin and D-dimer can effectively distinguish between patients who have VTE with and without hidden malignancies.

Cancer patients and ischemic stroke

Patients with cancer have an increased risk of ischemic stroke compared to the general population. Additionally, these patients have a worse prognosis compared to stroke patients without cancer. Activation of coagulation appears to play a key role in the pathophysiology of ischemic stroke in patients with cancer. However, the underlying mechanisms remain unknown. Moreover, we do not have a way to identify cancer patients with a high risk of stroke and cannot develop prevention strategies. Therefore, there is an urgent need for neurologists and oncologists to develop screening and prevention strategies for stroke in patients with cancer. In this review, we summarize the characteristics of cancer patients at a high risk of stroke, the predictors for the development of stroke and survival in cancer patients, and possible treatments.

The pathogenesis of cancer-associated thrombosis

Patients with cancer have a higher risk of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), compared to the general population. Cancer-associated thrombosis (CAT) is a thrombotic event that occurs as a complication of cancer or cancer therapy. Major factors determining VTE risk in cancer patients include not only treatment history and patient characteristics, but also cancer type and site. Cancer types can be broadly divided into three groups based on VTE risk: high risk (pancreatic, ovarian, brain, stomach, gynecologic, and hematologic), intermediate risk (colon and lung), and low risk (breast and prostate). This implies that the mechanism of VTE differs between cancer types and that specific VTE pathways may exist for different cancer types. This review summarizes the specific pathways that contribute to VTE in cancer patients, with a particular focus on leukocytosis, neutrophil extracellular traps (NETs), tissue factor (TF), thrombocytosis, podoplanin (PDPN), plasminogen activator inhibitor-1 (PAI-1), the intrinsic coagulation pathway, and von Willebrand factor (VWF).

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.

Ischemic Stroke in Cancer: Mechanisms, Biomarkers, and Implications for Treatment

Ischemic stroke is an important cause of morbidity and mortality in cancer patients. The underlying mechanisms linking cancer and stroke are not completely understood. Long-standing and more recent evidence suggests that cancer-associated prothrombotic states, along with treatment-related vascular toxicity, such as with chemotherapy and immunotherapy, contribute to an increased risk of ischemic stroke in cancer patients. Novel biomarkers, including coagulation, platelet and endothelial markers, cell-free DNA, and extracellular vesicles are being investigated for their potential to improve risk stratification and patient selection for clinical trials and to help guide personalized antithrombotic strategies. Treatment of cancer-related stroke poses unique challenges, including the need to balance the risk of recurrent stroke and other thromboembolic events with that of bleeding associated with antithrombotic therapy. In addition, how and when to restart cancer treatment after stroke remains unclear. In this review, we summarize current knowledge on the mechanisms underlying ischemic stroke in cancer, propose an etiological classification system unique to cancer-related stroke to help guide patient characterization, provide an overview of promising biomarkers and their clinical utility, and discuss the current state of evidence-based management strategies for cancer-related stroke. Ultimately, a personalized approach to stroke prevention and treatment is required in cancer patients, considering both the underlying cancer biology and the individual patient's risk profile.

Cancer and arterial thrombosis: therapeutic options

A State of the Art lecture titled "Cancer and Arterial Thrombosis: Therapeutic Options" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. This State of the Art review delves into the complex relationship between cancer and arterial thromboembolism (ATE), encompassing acute coronary syndrome, ischemic strokes, and peripheral arterial disease. The burden of cancer-associated ATE is not well defined, but studies indicate elevated risks, particularly in the 6 months after a cancer diagnosis. Incidence varies among cancer subtypes, with lung cancer displaying the highest rates. Additionally, the pathophysiology of cancer-associated ATE involves a multifaceted interplay of cancer-induced hypercoagulopathy, cancer therapy-related thrombosis, and personal risk factor contributors. ATEs are clinically heterogeneous and in the context of cancer have particular mechanistic differences compared with ATE patients without cancer. This requires modifications in approach and tailored management considerations. Specific etiologies contributing to ATE, such as coronary vasospasm and non-bacterial-thrombotic endocarditis, need to be considered. The diagnosis of cancer alone usually does not contraindicate patients to standard guideline-based therapies for the management of ATE, although nuances in treatment may need to be considered in light of the underlying cancer. Atrial fibrillation in cancer patients further complicates the thrombotic landscape. Cancer patients with atrial fibrillation are at a higher risk of ATE, necessitating careful consideration of anticoagulation therapy as clinical benefits and bleeding risks need to be weighed. ATE may also be a presenting sign of underlying malignancy, which requires increased awareness and focused clinical evaluation for cancer in selected cases. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

Cancer-Associated Thrombosis: Epidemiology, Pathophysiological Mechanisms, Treatment, and Risk Assessment

Cancer patients represent a growing population with drastically difficult care and a lowered quality of life, especially due to the heightened risk of vast complications. Thus, it is well established so far that one of the most prominent complications in individuals with cancer is venous thromboembolism. Since there are various improved methods for screening and diagnosing cancer and its complications, the incidence of cancer-associated thrombosis has been on the rise in recent years. Therefore, the high mortality and morbidity rates among these patients are not a surprise. Consequently, there is an excruciating need for understanding the mechanisms behind this complex process, as well as the imperative for adequate analysis and application of the most suitable steps for cancer-associated thrombosis prevention. There are various and numerous mechanisms offering potential answers to cancer-associated thrombosis, some of which have already been elucidated in various preclinical and clinical scenarios, yet further and more elaborate studies are crucial to understanding and preventing this complex and harsh clinical entity. This article elaborates on the growing incidence, mortality, morbidity, and risk factors of cancer-associated thrombosis while emphasizing the pathophysiological mechanisms in the light of various types of cancer in patients and summarizes the most novel therapy and prevention guidelines recommendations.

NLRP3-Induced NETosis: A Potential Therapeutic Target for Ischemic Thrombotic Diseases?

Ischemic thrombotic disease, characterized by the formation of obstructive blood clots within arteries or veins, is a condition associated with life-threatening events, such as stroke, myocardial infarction, deep vein thrombosis, and pulmonary embolism. The conventional therapeutic strategy relies on treatments with anticoagulants that unfortunately pose an inherent risk of bleeding complications. These anticoagulants primarily target clotting factors, often overlooking upstream events, including the release of neutrophil extracellular traps (NETs). Neutrophils are integral components of the innate immune system, traditionally known for their role in combating pathogens through NET formation. Emerging evidence has now revealed that NETs contribute to a prothrombotic milieu by promoting platelet activation, increasing thrombin generation, and providing a scaffold for clot formation. Additionally, NET components enhance clot stability and resistance to fibrinolysis. Clinical and preclinical studies have underscored the mechanistic involvement of NETs in the pathogenesis of thrombotic complications, since the clots obtained from patients and experimental models consistently exhibit the presence of NETs. Given these insights, the inhibition of NETs or NET formation is emerging as a promising therapeutic approach for ischemic thrombotic diseases. Recent investigations also implicate a role for the nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome as a mediator of NETosis and thrombosis, suggesting that NLRP3 inhibition may also hold potential for mitigating thrombotic events. Therefore, future preclinical and clinical studies aimed at identifying and validating NLRP3 inhibition as a novel therapeutic intervention for thrombotic disorders are imperative.

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.

Targeting Neutrophil Extracellular Traps for Stroke Prognosis: A Promising Path

Stroke has become the first cause of functional disability and one of the leading causes of mortality worldwide. Therefore, it is of crucial importance to develop accurate biomarkers to assess stroke risk and prognosis. Emerging evidence suggests that neutrophil extracellular trap (NET) levels may serve as a valuable biomarker to predict stroke occurrence and functional outcome. NETs are known to create a procoagulant state by serving as a scaffold for tissue factor (TF) and platelets inducing thrombosis by activating coagulation pathways and endothelium. A literature search was conducted in two databases (MEDLINE and Scopus) to trace all relevant studies published between 1 January 2016 and 31 December 2022, addressing the potential utility of NETs as a stroke biomarker. Only full-text articles in English were included. The current review includes thirty-three papers. Elevated NET levels in plasma and thrombi seem to be associated with increased mortality and worse functional outcomes in stroke, with all acute ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage included. Additionally, higher NET levels seem to correlate with worse outcomes after recanalization therapies and are more frequently found in strokes of cardioembolic or cryptogenic origin. Additionally, total neutrophil count in plasma seems also to correlate with stroke severity. Overall, NETs may be a promising predictive tool to assess stroke severity, functional outcome, and response to recanalization therapies.

Reprogramming the immunosuppressive tumor microenvironment: exploiting angiogenesis and thrombosis to enhance immunotherapy

This review focuses on the immunosuppressive effects of tumor angiogenesis and coagulation on the tumor microenvironment (TME). We summarize previous research efforts leveraging these observations and targeting these processes to enhance immunotherapy outcomes. Clinical trials have documented improved outcomes when combining anti-angiogenic agents and immunotherapy. However, their overall survival benefit over conventional therapy remains limited and certain tumors exhibit poor response to anti-angiogenic therapy. Additionally, whilst preclinical studies have shown several components of the tumor coagulome to curb effective anti-tumor immune responses, the clinical studies reporting combinations of anticoagulants with immunotherapies have demonstrated variable treatment outcomes. By reviewing the current state of the literature on this topic, we address the key questions and future directions in the field, the answers of which are crucial for developing effective strategies to reprogram the TME in order to further the field of cancer immunotherapy.

Release of extracellular superoxide dismutase into alveolar fluid protects against acute lung injury and inflammation in Staphylococcus aureus pneumonia

Acute respiratory distress syndrome (ARDS) remains a significant cause of morbidity and mortality in critically ill patients. Oxidative stress and inflammation play a crucial role in the pathogenesis of ARDS. Extracellular superoxide dismutase (EC-SOD) is abundant in the lung and is an important enzymatic defense against superoxide. Human single-nucleotide polymorphism in matrix binding region of EC-SOD leads to the substitution of arginine to glycine at position 213 (R213G) and results in release of EC-SOD into alveolar fluid, without affecting enzyme activity. We hypothesized that R213G EC-SOD variant protects against lung injury and inflammation via the blockade of neutrophil recruitment in infectious model of methicillin-resistant S. aureus (MRSA) pneumonia. After inoculation with MRSA, wild-type (WT) mice had impaired integrity of alveolar-capillary barrier and increased levels of IL-1β, IL-6, and TNF-α in the broncho-alveolar lavage fluid (BALF), while infected mice expressing R213G EC-SOD variant maintained the integrity of alveolar-capillary interface and had attenuated levels of proinflammatory cytokines. MRSA-infected mice expressing R213G EC-SOD variant also had attenuated neutrophil numbers in BALF and decreased expression of neutrophil chemoattractant CXCL1 by the alveolar epithelial ATII cells, compared with the infected WT group. The decreased neutrophil numbers in R213G mice were not due to increased rate of apoptosis. Mice expressing R213G variant had a differential effect on neutrophil functionality-the generation of neutrophil extracellular traps (NETs) but not myeloperoxidase (MPO) levels were attenuated in comparison with WT controls. Despite having the same bacterial load in the lung as WT controls, mice expressing R213G EC-SOD variant were protected from extrapulmonary dissemination of bacteria.

Tumor Genomic Profile Is Associated With Arterial Thromboembolism Risk in Patients With Solid Cancer

Background

Patients with cancer have an increased risk for arterial thromboembolism (ATE). Scant data exist about the impact of cancer-specific genomic alterations on the risk for ATE.

Objectives

The aim of this study was to determine whether individual solid tumor somatic genomic alterations influence the incidence of ATE.

Methods

A retrospective cohort study was conducted using tumor genetic alteration data from adults with solid cancers who underwent Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets testing between 2014 and 2016. The primary outcome, ATE, was defined as myocardial infarction, coronary revascularization, ischemic stroke, peripheral arterial occlusion, or limb revascularization and identified through systematic electronic medical record assessments. Patients were followed from date of tissue-matched blood control accession to first ATE event or death, for up to 1 year. Cause-specific Cox proportional hazards regression was used to determine HRs of ATE for individual genes adjusted for pertinent clinical covariates.

Results

Among 11,871 eligible patients, 74% had metastatic disease, and there were 160 ATE events. A significantly increased risk for ATE independent of tumor type was noted for the KRAS oncogene (HR: 1.98; 95% CI: 1.34-2.94; multiplicity-adjusted P = 0.015) and the STK11 tumor suppressor gene (HR: 2.51; 95% CI: 1.44-4.38; multiplicity-adjusted P = 0.015).

Conclusions

In a large genomic tumor-profiling registry of patients with solid cancers, alterations in KRAS and STK11 were associated with an increased risk for ATE independent of cancer type. Further investigation is needed to elucidate the mechanism by which these mutations contribute to ATE in this high-risk population.

The investigation on the hypercoagulability of hepatocellular carcinoma-related cerebral infarction with thromboelastography

AIM

To investigate the hypercoagulability of hepatocellular carcinoma (HCC)-related cerebral infarction (HCRCI) with thromboelastography (TEG).

METHODS

A multicenter prospective study was conducted in HCRCI patients, HCC patients without cerebral infarction, and acute cerebral infarction (ACI) patients without HCC between January 2016 and December 2019. TEG parameters and laboratory and clinical data were collected and compared among the three groups. To confirm the independent risk factors of HCRCI, multivariate analyses were conducted. Receiver operating characteristic (ROC) curves were utilized to evaluate the area under the curve (AUC) plotted by each independent risk factor.

RESULTS

There were 38 patients recruited in the HCRCI group, and 152 patients were recruited to the HCC group and the ACI group. The levels of plasma neutrophil count, D-dimer, α-fetoprotein (AFP), carcinoembryonic antigen, and maximum amplitude (MA)-a parameter of TEG-were significantly higher in the HCRCI group than HCC and ACI groups. Multivariate logistic regression analysis showed that increased neutrophile count, D-dimer, AFP, and MA were independently associated with HCRCI. ROC curve analysis showed first that AUC of MA for HCRCI was .875, which was larger than the other risk factors, and second that the optimal cutoff value for MA was 61.35, with a sensitivity of 89.50% and specificity of 66.40%.

CONCLUSION

It was suggested that TEG disclosed that the pathogenesis of HCRIC is exactly related to the hypercoagulability. And with a cutoff value of MA equaling to 61.35, TEG facilitates clinicians to identify HCC patients at high risk of HCRIC.

NETworking with cancer: The bidirectional interplay between cancer and neutrophil extracellular traps

Neutrophils are major effectors and regulators of the immune system. They play critical roles not only in the eradication of pathogens but also in cancer initiation and progression. Conversely, the presence of cancer affects neutrophil activity, maturation, and lifespan. By promoting or repressing key neutrophil functions, cancer cells co-opt neutrophil biology to their advantage. This co-opting includes hijacking one of neutrophils' most striking pathogen defense mechanisms: the formation of neutrophil extracellular traps (NETs). NETs are web-like filamentous extracellular structures of DNA, histones, and cytotoxic granule-derived proteins. Here, we discuss the bidirectional interplay by which cancer stimulates NET formation, and NETs in turn support disease progression. We review how vascular dysfunction and thrombosis caused by neutrophils and NETs underlie an elevated risk of death from cardiovascular events in cancer patients. Finally, we propose therapeutic strategies that may be effective in targeting NETs in the clinical setting.

Neutrophil interactions with T cells, platelets, endothelial cells, and of course tumor cells

Neutrophils sense microbes and host inflammatory mediators, and traffic to sites of infection where they direct a broad armamentarium of antimicrobial products against pathogens. Neutrophils are also activated by damage-associated molecular patterns (DAMPs), which are products of cellular injury that stimulate the innate immune system through pathways that are similar to those activated by microbes. Neutrophils and platelets become activated by injury, and cluster and cross-signal to each other with the cumulative effect of driving antimicrobial defense and hemostasis. In addition, neutrophil extracellular traps are extracellular chromatin and granular constituents that are generated in response to microbial and damage motifs and are pro-thrombotic and injurious. Although neutrophils can worsen tissue injury, neutrophils may also have a role in facilitating wound repair following injury. A central theme of this review relates to how critical functions of neutrophils that evolved to respond to infection and damage modulate the tumor microenvironment (TME) in ways that can promote or limit tumor progression. Neutrophils are reprogrammed by the TME, and, in turn, can cross-signal to tumor cells and reshape the immune landscape of tumors. Importantly, promising new therapeutic strategies have been developed to target neutrophil recruitment and function to make cancer immunotherapy more effective.

Hydrogel delivery of purinergic enzymes improves cardiac ischemia/reperfusion injury

RATIONALE

The innate immune response contributes to cardiac injury in myocardial ischemia/reperfusion (MI/R). Neutrophils are an important early part of the innate immune response to MI/R. Adenosine, an endogenous purine, is a known innate immune modulator and inhibitor of neutrophil activation. However, its delivery to the heart is limited by its short half-life (<30 s) and off-target side effects. CD39 and CD73 are anti-inflammatory homeostatic enzymes that can generate adenosine from phosphorylated adenosine substrate such as ATP released from injured tissue.

OBJECTIVE

We hypothesize that hydrogel-delivered CD39 and CD73 target the local early innate immune response, reduce neutrophil activation, and preserve cardiac function in MI/R injury.

METHODS AND RESULTS

We engineered a poly(ethylene) glycol (PEG) hydrogel loaded with the adenosine-generating enzymes CD39 and CD73. We incubated the hydrogels with neutrophils in vitro and showed a reduction in hydrogen peroxide production using Amplex Red. We demonstrated availability of substrate for the enzymes in the myocardium in MI/R by LC/MS, and tested release kinetics from the hydrogel. On echocardiography, global longitudinal strain (GLS) was preserved in MI/R hearts treated with the loaded hydrogel. Delivery of purinergic enzymes via this synthetic hydrogel resulted in lower innate immune infiltration into the myocardium post-MI/R, decreased markers of macrophage and neutrophil activation (NETosis), and decreased leukocyte-platelet complexes in circulation.

CONCLUSIONS

In a rat model of MI/R injury, CD39 and CD73 delivered via a hydrogel preserve cardiac function by modulating the innate immune response.

Increased levels of NETosis biomarkers in high-grade serous ovarian cancer patients' biofluids: Potential role in disease diagnosis and management

Introduction

High-grade serous ovarian cancer (HGSOC) is the second most frequent gynecological malignancy but the most lethal, partially due to the spread of the disease through the peritoneal cavity. Recent evidence has shown that, apart from their role in immune defense through phagocytosis and degranulation, neutrophils are able to participate in cancer progression through the release of neutrophil extracellular traps (NETs) in a process called NETosis. NETs are composed of DNA, histones, calprotectin, myeloperoxidase (MPO) and elastase and the NETosis process has been proposed as a pre-requisite for the establishment of omental metastases in early stages of HGSOC. Nevertheless, its role in advanced stages remains to be elucidated. Therefore, our principal aim is to characterize a NETosis biomarker profile in biofluids from patients with advanced HGSOC and control women.

Methods

Specifically, five biomarkers of NETosis (cell-free DNA (cfDNA), nucleosomes, citrullinated histone 3 (citH3), calprotectin and MPO) were quantified in plasma and peritoneal fluid (PF) samples from patients (n=45) and control women (n=40).

Results

Our results showed that HGSOC patients presented a higher concentration of cfDNA, citH3 and calprotectin in plasma and of all five NETosis biomarkers in PF than control women. Moreover, these biomarkers showed a strong ability to differentiate the two clinical groups. Interestingly, neoadjuvant treatment (NT) seemed to reduce NETosis biomarkers mainly systemically (plasma) compared to the tumor environment (PF).

Discussion

In conclusion, NETosis biomarkers are present in the tumor environment of patients with advanced HGSOC, which might contribute to the progression of the disease. Besides, plasma cfDNA and calprotectin could represent minimally invasive surrogate biomarkers for HGSOC. Finally, NT modifies NETosis biomarkers levels mainly at the systemic level.

Spatiotemporal profile of neutrophil extracellular trap formation in a mouse model of ischemic stroke

Background

Thromboinflammatory processes modulate the complex pathophysiology of cerebral ischemia-reperfusion (I/R) injury in ischemic stroke, but the exact underlying mechanisms remain poorly understood. Emerging evidence indicates that neutrophil extracellular traps (NETs) might play an important role in the thromboinflammatory cascade. In addition, the link between von Willebrand factor (VWF) and neutrophil recruitment in the ischemic brain might promote thromboinflammation, possibly by the formation of NETs.

Objectives

To study NET formation in a murine model of cerebral I/R injury in ischemic stroke.

Methods

The filament-induced transient middle cerebral artery occlusion model was used to induce 60 minutes of focal cerebral ischemia after which reperfusion was allowed. At different time points postischemia, NETs were identified in the ischemic mouse brain using quantitative immunofluorescence microscopy.

Results

NETs could be identified in the ipsilateral brain hemisphere. Interestingly, NETs could already be detected at 6 hours poststroke. Their presence increased at 12 hours, was highest at 24 hours, and decreased again 48 hours postischemia. Remarkably, NETs were predominantly localized within the brain vasculature postischemia, suggesting that NETs play a role in secondary microthrombosis. Strikingly, NET formation was significantly decreased in VWF-deficient mice compared to littermate wild-type mice 24 hours postischemia, indicating a possible role for VWF in promoting NETosis in the ischemic brain.

Conclusion

This study identified the spatiotemporal profile of NET formation in a mouse model of cerebral I/R injury in ischemic stroke. NETs, potentially in combination with VWF, might be attractive targets for the development of novel therapeutic strategies in ischemic stroke treatment.

When Two Maladies Meet: Disease Burden and Pathophysiology of Stroke in Cancer

Stroke and cancer are disabling diseases with an enormous global burden, disproportionately affecting vulnerable populations and low- and middle-income countries. Both these diseases share common risk factors, which warrant concerted attention toward reshaping population health approaches and the conducting of fundamental studies. In this article, an overview of epidemiological trends in the prevalence and burden of cancer and stroke, underlying biological mechanisms and clinical risk factors, and various tools available for risk prediction and prognosis are provided. Finally, future recommendations for research and existing gaps in our understanding of pathophysiology. Further research must investigate the causes that predispose patients to an increased risk of stroke and/or cancer, as well as biomarkers that can be used to predict growing morbidity and mortality.

Advances in brain-heart syndrome: Attention to cardiac complications after ischemic stroke

Neurocardiology is an emerging field that studies the interaction between the brain and the heart, namely the effects of heart injury on the brain and the effects of brain damage on the heart. Acute ischemic stroke has long been known to induce heart damage. Most post-stroke deaths are attributed to nerve damage, and cardiac complications are the second leading cause of death after stroke. In clinical practice, the proper interpretation and optimal treatment for the patients with heart injury complicated by acute ischemic stroke, recently described as stroke-heart syndrome (SHS), are still unclear. Here, We describe a wide range of clinical features and potential mechanisms of cardiac complications after ischemic stroke. Autonomic dysfunction, microvascular dysfunction and coronary ischemia process are interdependent and play an important role in the process of cardiac complications caused by stroke. As a unique comprehensive view, SHS can provide theoretical basis for research and clinical diagnosis and treatment.

PAD4 and Its Inhibitors in Cancer Progression and Prognosis

The systemic spread of malignancies and the risk of cancer-associated thrombosis are major clinical challenges in cancer therapy worldwide. As an important post-translational modification enzyme, peptidyl arginine deiminase 4 (PAD4) could mediate the citrullination of protein in different components (including nucleus and cytoplasm, etc.) of a variety of cells (tumor cells, neutrophils, macrophages, etc.), thus participating in gene regulation, neutrophil extracellular trap (NET) and macrophage extracellular trap (MET). Thereby, PAD4 plays an important role in enhancing the growth of primary tumors and facilitating the distant metastasis of cancer cells. In addition, it is related to the formation of cancer-associated thrombosis. Therefore, the development of PAD4-specific inhibitors may be a promising strategy for treating cancer, and it may improve patient prognosis. In this review, we describe PAD4 involvement in gene regulation, protein citrullination, and NET formation. We also discuss its potential role in cancer and cancer-associated thrombosis, and we summarize the development and application of PAD4 inhibitors.

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.

Platelets in the NETworks interweaving inflammation and thrombosis

Platelets are well characterized for their indispensable role in primary hemostasis to control hemorrhage. Research over the past years has provided a substantial body of evidence demonstrating that platelets also participate in host innate immunity. The surface expression of pattern recognition receptors, such as TLR2 and TLR4, provides platelets with the ability to sense bacterial products in their environment. Platelet α-granules contain microbicidal proteins, chemokines and growth factors, which upon release may directly engage pathogens and/or contribute to inflammatory signaling. Additionally, platelet interactions with neutrophils enhance neutrophil activation and are often crucial to induce a sufficient immune response. In particular, platelets can activate neutrophils to form neutrophil extracellular traps (NETs). This specific neutrophil effector function is characterized by neutrophils expelling chromatin fibres decorated with histones and antimicrobial proteins into the extracellular space where they serve to trap and kill pathogens. Until now, the mechanisms and signaling pathways between platelets and neutrophils inducing NET formation are still not fully characterized. NETs were also detected in thrombotic lesions in several disease backgrounds, pointing towards a role as an interface between neutrophils, platelets and thrombosis, also known as immunothrombosis. The negatively charged DNA within NETs provides a procoagulant surface, and in particular NET-derived proteins may directly activate platelets. In light of the current COVID-19 pandemic, the topic of immunothrombosis has become more relevant than ever, as a majority of COVID-19 patients display thrombi in the lung capillaries and other vascular beds. Furthermore, NETs can be found in the lung and other tissues and are associated with an increased mortality. Here, virus infiltration may lead to a cytokine storm that potently activates neutrophils and leads to massive neutrophil infiltration into the lung and NET formation. The resulting NETs presumably activate platelets and coagulation factors, further contributing to the subsequent emergence of microthrombi in pulmonary capillaries. In this review, we will discuss the interplay between platelets and NETs and the potential of this alliance to influence the course of inflammatory diseases. A better understanding of the underlying molecular mechanisms and the identification of treatment targets is of utmost importance to increase patients’ survival and improve the clinical outcome.

Neutrophil phenotypes and functions in cancer: A consensus statement

Neutrophils are the first responders to infection and inflammation and are thus a critical component of innate immune defense. Understanding the behavior of neutrophils as they act within various inflammatory contexts has provided insights into their role in sterile and infectious diseases; however, the field of neutrophils in cancer is comparatively young. Here, we summarize key concepts and current knowledge gaps related to the diverse roles of neutrophils throughout cancer progression. We discuss sources of neutrophil heterogeneity in cancer and provide recommendations on nomenclature for neutrophil states that are distinct in maturation and activation. We address discrepancies in the literature that highlight a need for technical standards that ought to be considered between laboratories. Finally, we review emerging questions in neutrophil biology and innate immunity in cancer. Overall, we emphasize that neutrophils are a more diverse population than previously appreciated and that their role in cancer may present novel unexplored opportunities to treat cancer.

Stroke-derived neutrophils demonstrate higher formation potential and impaired resolution of CD66b + driven neutrophil extracellular traps

Background

Recent evidence suggests a merging role of immunothrombosis in the formation of arterial thrombosis. Our study aims to investigate its relevance in stroke patients.

Methods

We compared the peripheral immunological profile of stroke patients vs. healthy controls. Serum samples were functionally analyzed for their formation and clearance of Neutrophil-Extracellular-Traps. The composition of retrieved thrombi has been immunologically analyzed.

Results

Peripheral blood of stroke patients showed significantly elevated levels of DNAse-I (p < 0.001), LDG (p = 0.003), CD4 (p = 0.005) as well as the pro-inflammatory cytokines IL-17 (p < 0.001), INF-γ (p < 0.001) and IL-22 (p < 0.001) compared to controls, reflecting a T_H1/T_H17 response. Increased counts of DNAse-I in sera (p = 0.045) and Neutrophil-Extracellular-Traps in thrombi (p = 0.032) have been observed in patients with onset time of symptoms longer than 4,5 h. Lower values of CD66b in thrombi were independently associated with greater improvement of NIHSS after mechanical thrombectomy (p = 0.045). Stroke-derived neutrophils show higher potential for Neutrophil-Extracellular-Traps formation after stimulation and worse resolution under DNAse-I treatment compared to neutrophils derived from healthy individuals.

Conclusions

Our data provide new insight in the role of activated neutrophils and Neutrophil-Extracellular-Traps in ischemic stroke. Future larger studies are warranted to further investigate the role of immunothrombosis in the cascades of stroke.

Trial registration

DRKS, DRKS00013278, Registered 15 November 2017, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00013278

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02707-0.

Extracellular DNA Traps: Origin, Function and Implications for Anti-Cancer Therapies

Extracellular DNA may serve as marker in liquid biopsies to determine individual diagnosis and prognosis in cancer patients. Cell death or active release from various cell types, including immune cells can result in the release of DNA into the extracellular milieu. Neutrophils are important components of the innate immune system, controlling pathogens through phagocytosis and/or the release of neutrophil extracellular traps (NETs). NETs also promote tumor progression and metastasis, by modulating angiogenesis, anti-tumor immunity, blood clotting and inflammation and providing a supportive niche for metastasizing cancer cells. Besides neutrophils, other immune cells such as eosinophils, dendritic cells, monocytes/macrophages, mast cells, basophils and lymphocytes can also form extracellular traps (ETs) during cancer progression, indicating possible multiple origins of extracellular DNA in cancer. In this review, we summarize the pathomechanisms of ET formation generated by different cell types, and analyze these processes in the context of cancer. We also critically discuss potential ET-inhibiting agents, which may open new therapeutic strategies for cancer prevention and treatment.

Neutrophil Extracellular Trap Targeting Protects Against Ischemic Damage After Fibrin-Rich Thrombotic Stroke Despite Non-Reperfusion

Stroke is one of the most prevalent diseases worldwide caused primarily by a thrombotic vascular occlusion that leads to cell death. To date, t-PA (tissue-type plasminogen activator) is the only thrombolytic therapy approved which targets fibrin as the main component of ischemic stroke thrombi. However, due to its highly restrictive criteria, t-PA is only administrated to less than 10% of all stroke patients. Furthermore, the research in neuroprotective agents has been extensive with no translational results from medical research to clinical practice up to now. Since we first described the key role of NETs (Neutrophil Extracellular Traps) in platelet-rich thrombosis, we asked, first, whether NETs participate in fibrin-rich thrombosis and, second, if NETs modulation could prevent neurological damage after stroke. To this goal, we have used the thromboembolic in situ stroke model which produces fibrin-rich thrombotic occlusion, and the permanent occlusion of the middle cerebral artery by ligature. Our results demonstrate that NETs do not have a predominant role in fibrin-rich thrombosis and, therefore, DNase-I lacks lytic effects on fibrin-rich thrombosis. Importantly, we have also found that NETs exert a deleterious effect in the acute phase of stroke in a platelet-TLR4 dependent manner and, subsequently, that its pharmacological modulation has a neuroprotective effect. Therefore, our data strongly support that the pharmacological modulation of NETs in the acute phase of stroke, could be a promising strategy to repair the brain damage in ischemic disease, independently of the type of thrombosis involved.

Neutrophil extracellular traps promote cancer-associated inflammation and myocardial stress

Cancer is associated with systemic pathologies that contribute to mortality, such as thrombosis and distant organ failure. The aim of this study was to investigate the potential role of neutrophil extracellular traps (NETs) in myocardial inflammation and tissue damage in treatment-naïve individuals with cancer. Mice with mammary carcinoma (MMTV-PyMT) had increased plasma levels of NETs measured as H3Cit-DNA complexes, paralleled with elevated coagulation, compared to healthy littermates. MMTV-PyMT mice displayed upregulation of pro-inflammatory markers in the heart, myocardial hypertrophy and elevated cardiac disease biomarkers in the blood, but not echocardiographic heart failure. Moreover, increased endothelial proliferation was observed in hearts from tumor-bearing mice. Removal of NETs by DNase I treatment suppressed the myocardial inflammation, expression of cardiac disease biomarkers and endothelial proliferation. Compared to a healthy control group, treatment-naïve cancer patients with different malignant disorders had increased NET formation, which correlated to plasma levels of the inflammatory marker CRP and the cardiac disease biomarkers NT-proBNP and sTNFR1, in agreement with the mouse data. Altogether, our data indicate that NETs contribute to inflammation and myocardial stress during malignancy. These findings suggest NETs as potential therapeutic targets to prevent cardiac inflammation and dysfunction in cancer patients.

Neutrophils, Cancer and Thrombosis: The New Bermuda Triangle in Cancer Research

Spontaneous venous thrombosis is often the first clinical sign of cancer, and it is linked to a worsened survival rate. Traditionally, tumor-cell induced platelet activation has been the main actor studied in cancer-associated-thrombosis. However, platelet involvement alone does not seem to be sufficient to explain this heightened pro-thrombotic state. Neutrophils are emerging as key players in both thrombus generation and cancer progression. Neutrophils can impact thrombosis through the release of pro-inflammatory cytokines and expression of molecules like P-selectin and Tissue Factor (TF) on their membrane and on neutrophil-derived microvesicles. Their role in cancer progression is evidenced by the fact that patients with high blood-neutrophil counts have a worsened prognosis. Tumors can attract neutrophils to the cancer site via pro-inflammatory cytokine secretions and induce a switch to pro-tumoral (or N2) neutrophils, which support metastatic spread and have an immunosuppressive role. They can also expel their nuclear contents to entrap pathogens forming Neutrophil Extracellular Traps (NETs) and can also capture coagulation factors, enhancing the thrombus formation. These NETs are also known to have pro-tumoral effects by supporting the metastatic process. Here, we strived to do a comprehensive literature review of the role of neutrophils as drivers of both cancer-associated thrombosis (CAT) and cancer progression.

The histopathological features and their prognostic impact in the postoperative follow-up of colorectal cancer patients

The validation of histological prognostic markers in colorectal cancer not only for survival parameters but also for early postoperative outcomes is of paramount importance. The aim of our study was to search for the tumor histopathological (HP) characteristics that may influence the postoperative morbidity, especially the occurrence of anastomotic leakage. Our results indicated that peritumoral inflammatory cell infiltrate appeared to correlate with both anastomotic fistula and overall postoperative complications. Likewise, high-grade and undifferentiated colorectal tumors seemed to be correlated with a higher incidence of postoperative leakage and complications. No relation could be established between the other HP features and the postoperative untoward outcomes.

Casting a NET on cancer: the multiple roles for neutrophil extracellular traps in cancer

PURPOSE OF REVIEW

The role of the innate immune system has become widely appreciated in cancer and cancer-associated disorders. Neutrophils, the most abundant circulating leukocytes, have prognostic value in determining cancer progression and survival. One of the ways by which neutrophils negatively impact outcome is by formation of neutrophil extracellular traps (NETs) which result in release of nuclear chromatin and bioactive proteins into the extracellular space. Here, we review the evidence for NETs contributions to cancer progression, metastasis, and cancer-associated thrombosis (CAT).

RECENT FINDINGS

NETs are increased across several cancer types and predict progression and adverse outcome. Several preclinical and clinical observations implicate NETs in promoting tumor growth, angiogenesis and metastasis via distinct pathways. Furthermore, NETs are shown to contribute to resistance to immunotherapy. NETs also emerge as key players in the prothrombotic phenotype associated with cancer that can result in potentially life-threatening arterial and venous thrombosis. Recent mechanistic insights expose several potential targets to inhibit NET formation and disrupt the interaction between NETs and tumor cells.

SUMMARY

Clinical and translational insights highlight the central role of NETs in cancer progression and metastasis, disease resistance and CAT. Targeting NETs and NET-associated pathways may represent a novel approach to treat cancer.

Clinical and morphopathological assay in vulvovaginal candidiasis

Candida vulvovaginitis is characterized by the appearance of inflammatory changes in the vaginal and vulvar epithelium secondary to infection with Candida species. The purpose of this study was to analyze and compare the clinical, microbiological, and histopathological aspects of pregnant and non-pregnant patients, symptomatic or asymptomatic in the case of candida vaginitis and to correlate the microscopic aspects with the symptoms before applying the local treatment with Nystatin. The study presents a retrospective analysis of the management of vaginitis in 166 pregnant or non-pregnant patients during 2021-2022. We observed the structure of the Malpighian squamous epithelium without keratinization present on the vaginal mucosa and the structure of the subepithelial connective tissue, which shows increased numerical values of inflammatory and vascular cellularity in the case of candida vaginitis symptomatic compared to asymptomatic ones. We noticed also in the microscopic study that in cases of asymptomatic patients before treatment, the number of inflammatory cells and blood vessels situated immediately under the epithelium was significantly lower compared to their number in symptomatic patients before treatment. Analyzing the results obtained after the administration of the treatment proposed by us, we can say that local Nystatin treatment is beneficial and safe for pregnant and non-pregnant patients and is a good alternative for patients with recurrent vulvovaginal candidiasis.

Prognostic Significance of NLR About NETosis and Lymphocytes Perturbations in Localized Renal Cell Carcinoma With Tumor Thrombus

Background

Non-metastatic renal cell carcinoma (RCC) with tumor thrombus showed a greater tendency for developing metastases after surgery. Early identification of patients with high risk of poor prognosis is especially important to explore adjuvant treatment of improving outcomes. Neutrophil-to-lymphocyte ratio (NLR) was a systemic inflammation marker and outcome predictor in RCC, reflecting the chaos in systemic immune status in cancer as myeloid cell expansion and lymphatic cell suppression. Neutrophil extracellular traps (NET) formation (NETosis) is the process of neutrophils generating an extracellular DNA net-like structure. NETosis in tumor was demonstrated to conduce to the subsequent metastases of tumor. However, the role of NLR for systemic immune status and tumor local immune infiltration, especially for neutrophil-associated NETs, in non-metastatic RCC with thrombus remains unclear.

Patients and Methods

In our clinical cohort, we enrolled the clinical, pathologic, and preoperative laboratory parameters of 214 RCC patients with tumor thrombus who were treated surgically. The clinical endpoint was defined as cancer-specific survival (CSS). In our basic research cohort, RNA-seq, TCR-seq, and scRNA-seq data were analyzed. Patients who reached the endpoint as recurrence-free survival (RFS) were defined as the “High-risk” group. Otherwise, they were separated into the “Low-risk” group.

Results

In the clinical cohort, NLR≥4 was an independent risk factor for 203 localized RCC with tumor thrombus. In the basic research cohort, tumor thrombi were separated into NETosis-thrombi belonging to the “High-risk” group and non-NETosis-thrombi to the “Low-risk” group. NETs induced by tumor-derived G-CSF in tumor thrombus has a mechanistic role in unfavorable prognosis. Besides, NETs-score from single sample GSEA (ssGSEA) algorithm was an independent prognostic factor validated in the TCGA data. Apart from the neutrophils-associated NETosis, systemic immune perturbations of lymphocytes occurred in the “High-risk” group, represented with decreased TCR diversity and increasingly high proportion of CD4-positive effector memory T (Tem) cells, which indirectly represented the state of lymphopenia.

Conclusions

Our findings firstly demonstrated that neutrophils-associated NETosis and systemic lymphocytes perturbations were considered as tumor progression in patients of localized RCC with tumor thrombus, which reflected NLR≥4 as an independent risk factor for patients.

The Emerging Role of Neutrophil Extracellular Traps in Arterial, Venous and Cancer-Associated Thrombosis

Neutrophils play a vital role in the formation of arterial, venous and cancer-related thrombosis. Recent studies have shown that in a process known as NETosis, neutrophils release proteins and enzymes complexed to DNA fibers, collectively called neutrophil extracellular traps (NETs). Although NETs were originally described as a way for the host to capture and kill bacteria, current knowledge indicates that NETs also play an important role in thrombosis. According to recent studies, the destruction of vascular microenvironmental homeostasis and excessive NET formation lead to pathological thrombosis. In vitro experiments have found that NETs provide skeletal support for platelets, red blood cells and procoagulant molecules to promote thrombosis. The protein components contained in NETs activate the endogenous coagulation pathway to promote thrombosis. Therefore, NETs play an important role in the formation of arterial thrombosis, venous thrombosis and cancer-related thrombosis. This review will systematically summarize and explain the study of NETs in thrombosis in animal models and in vivo experiments to provide new targets for thrombosis prevention and treatment.

Role of Cell-Free DNA and Deoxyribonucleases in Tumor Progression

Many studies have reported an increase in the level of circulating cell-free DNA (cfDNA) in the blood of patients with cancer. cfDNA mainly comes from tumor cells and, therefore, carries features of its genomic profile. Moreover, tumor-derived cfDNA can act like oncoviruses, entering the cells of vulnerable organs, transforming them and forming metastatic nodes. Another source of cfDNA is immune cells, including neutrophils that generate neutrophil extracellular traps (NETs). Despite the potential eliminative effect of NETs on tumors, in some cases, their excessive generation provokes tumor growth as well as invasion. Considering both possible pathological contributions of cfDNA, as an agent of oncotransformation and the main component of NETs, the study of deoxyribonucleases (DNases) as anticancer and antimetastatic agents is important and promising. This review considers the pathological role of cfDNA in cancer development and the role of DNases as agents to prevent and/or prohibit tumor progression and the development of metastases.

Neutrophil Extracellular Traps (NETs) and Hypercoagulability in Plasma Cell Dyscrasias-Is This Phenomenon Worthy of Exploration?

Plasma cell dyscrasias (PCDs) are neoplastic diseases derived from plasma cells. Patients suffering from PCDs are at high risk of hypercoagulability and thrombosis. These conditions are associated with disease-related factors, patient-related factors, or the use of immunomodulatory drugs. As PCDs belong to neoplastic diseases, some other factors related to the cancer-associated hypercoagulability state in the course of PCDs are also considered. One of the weakest issues studied in PCDs is the procoagulant activity of neutrophil extracellular traps (NETs). NETs are web-like structures released from neutrophils in response to different stimuli. These structures are made of deoxyribonucleic acid (DNA) and bactericidal proteins, such as histones, myeloperoxidase, neutrophil elastase, and over 300 other proteins, which are primarily stored in neutrophil granules. NETs immobilize, inactivate the pathogens, and expose them to specialized cells of immune response. Despite their pivotal role in innate immunity, they contribute to the development and exacerbation of autoimmune diseases, trigger inflammatory response, or even facilitate the formation of cancer metastases. NETs were also found to induce activity of coagulation and are considered one of the most important factors inducing thrombosis. Here, we summarize how PCDs influence the release of NETs, and hypothesize whether NETs contribute to hypercoagulability in PCDs patients.

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.

Neutrophil extracellular trap formation index predicts occurrences of deep surgical site infection after laparotomy

Background

Deep surgical site infections (DSSIs) are serious complications after laparotomy. Neutrophil extracellular traps (NETs) play a vital role in the development of DSSI. Here, we focused on a new approach to predicting the occurrence of DSSI through the detection of the NET formation index (NFI), and compared its prediction ability with other clinical infection indicators.

Methods

Patients who received laparotomy were prospectively enrolled in this study. General information, APACHE II score, SOFA score, and serum infection indicators were recorded. The postoperative abdominal drainage fluid was collected within 3 days after the operation for quantification of the NFI.

Results

A total of 92 consecutive patients were included, with 22 patients were diagnosed with DSSI. The NFI in the DSSI group was 32.70%±19.33% while the corresponding index was 10.70%±8.25% in the non-DSSI group (P<0.01). The mean APACHE II and SOFA score had significant differences between the two groups. The NFI was positively correlated with the APACHE II score (P<0.01, r=0.269) and SOFA score (P=0.013, r=0.258). Patients with a high NFI (NFI >13.86%) had a higher risk of developing DSSI. According to the receiver operating characteristic (ROC) curve, the area under the ROC curve (AUC) of the NFI, C-reactive protein (CRP) and procalcitonin (PCT) were 0.912, 0.748 and 0.731, respectively.

Conclusions

In this cohort of surgical patients, the quantification of the NFI had a considerable predictive value for early identification of DSSI. The NFI in drainage fluid turned out to be a more sensitive and specific predictor of DSSI than serum infection indicators including CRP and PCT.

The Role of Neutrophil Extracellular Traps in Cancer

Neutrophils are vital components of innate and adaptive immunity. It is widely acknowledged that in various pathological conditions, neutrophils are activated and release condensed DNA strands, triggering the formation of neutrophil extracellular traps (NETs). NETs have been shown to be effective in fighting against microbial infections and modulating the pathogenesis and progression of diseases, including malignant tumors. This review describes the current knowledge on the biological characteristics of NETs. Additionally, the mechanisms of NETs in cancer are discussed, including the involvement of signaling pathways and the crosstalk between other cancer-related mechanisms, including inflammasomes and autophagy. Finally, based on previous and current studies, the roles of NET formation and the potential therapeutic targets and strategies related to NETs in several well-studied types of cancers, including breast, lung, colorectal, pancreatic, blood, neurological, and cutaneous cancers, are separately reviewed and discussed.

Neutrophil Extracellular Trapping Role in Cancer, Metastases, and Cancer-Related Thrombosis: a Narrative Review of the Current Evidence Base

Purpose of Review

Neutrophil extracellular trap (NET) formation is a newly discovered, reactive oxygen species-dependent regulated process, whereby neutrophils degranulate and extrude genetic material, after engulfing various infectious or neoplastic antigens, culminating in a measurable serologic footprint. Recent research has highlighted the involvement of NETs in cancer and cancer-related pathologies. We review the role of NET formation in cancer biology, prognosis and potential therapeutic modulators.

Recent Findings

Elevated NET levels are associated with cancer metastasis and may be modified by some anaesthetic-analgesic techniques during tumour resection surgery. It promotes tumour cell migration, angiogenesis and hypercoagulability. Although there are potential anti-NET formation therapeutics available, their role has not been formally assessed in cancer patients.

Summary

Limited available evidence suggests an association between elevated NET expression and cancer metastasis, but its validity as a prognostic indicator for cancer-related outcomes is inconclusive. Further observational and interventional studies are warranted to comprehend the potential prognostic and therapeutic role of NETs in cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11912-021-01103-0.

Neutrophil Extracellular Traps in Fatal COVID-19-Associated Lung Injury

An excess formation of neutrophil extracellular traps (NETs), previously shown to be strongly associated with cytokine storm and acute respiratory distress syndrome (ARDS) with prevalent endothelial dysfunction and thrombosis, has been postulated to be a central factor influencing the pathophysiology and clinical presentation of severe COVID-19. A growing number of serological and morphological evidence has added to this assumption, also in regard to potential treatment options. In this study, we used immunohistochemistry and histochemistry to trace NETs and their molecular markers in autopsy lung tissue from seven COVID-19 patients. Quantification of key immunomorphological features enabled comparison with non-COVID-19 diffuse alveolar damage. Our results strengthen and extend recent findings, confirming that NETs are abundantly present in seriously damaged COVID-19 lung tissue, especially in association with microthrombi of the alveolar capillaries. In addition, we provide evidence that low-density neutrophils (LDNs), which are especially prone to NETosis, contribute substantially to COVID-19-associated lung damage in general and vascular blockages in particular.

Association of programmed cell death ligand 1 and circulating lymphocytes with risk of venous thromboembolism in patients with glioma

Introduction

The role of the adaptive immune system in the pathophysiology of cancer-associated venous thromboembolism (VTE) has not been investigated in detail. Programmed cell death ligand 1 (PD-L1) is an immune checkpoint molecule responsible for immune evasion in several cancer entities, as expression on tumour cells silences the T cell-mediated immune response. Given the interrelation between inflammation, haemostasis and cancer, we aimed to investigate the association of players of the adaptive immunity (eg, lymphocytes, tumour PD-L1) with risk of VTE in patients with glioma, one of the most prothrombotic cancer types.

Methods

In this prospective observational single-centre cohort study, patients with newly diagnosed glioma or regrowth after resection were included. Primary endpoint was objectively confirmed VTE. At study inclusion, a blood draw was performed. Tumour PD-L1 expression was assessed via immunohistochemistry.

Results

In total, 193 patients were included. PD-L1 expression in ≥1% of tumour cells was observed in 20/193 (10.4%) glioma. In multivariable cox-regression analysis, on adjustment for age, sex and WHO grade IV, systemic lymphocyte counts were significantly associated with risk of VTE (HR per 1 G/L increase (95% CI): 1.15 (1.03 to 1.29), p=0.013). In contrast, no significant difference in risk of VTE was found regarding the PD-L1 status: the cumulative 24 months probability of VTE was 17.0% in patients with no PD-L1 and 11.8% in those with PD-L1 expressing tumours (p=0.663).

Conclusion

In summary, PD-L1 expression was not associated with risk of VTE. Interestingly, peripheral lymphocytes, which are key players in adaptive immunity, were linked to an increased risk of glioma-associated VTE.

Neutrophil extracellular traps in cancer: not only catching microbes

Neutrophils are the most abundant type of white blood cells circulating throughout the bloodstream and are often considered the frontline defenders in innate immunity. However, neutrophils are increasingly being recognized as having an important role in tumorigenesis and carcinogenesis due to their aberrant activation by molecules released into the tumor microenvironment. One defensive response of neutrophils that is aberrantly triggered during the neoplastic process is called NETosis, where activated neutrophils expel their DNA and intracellular contents in a web-like structure known as a neutrophil extracellular trap (NET). In cancer, NETosis has been linked to increased disease progression, metastasis, and complications such as venous thromboembolism. NET structures released by neutrophils can also serve as a scaffold for clot formation, shining new light on the role of neutrophils and NETosis in coagulation-mediated diseases.

Here, we review current available knowledge regarding NET and the related NETosis process in cancer patients, with an emphasis on pre-clinical and clinical data fostering the identification and validation of biomarkers of NET with a predictive/prognostic role in cancer patients treated with immunotherapy agents. NETosis biomarkers, e.g., citH3, may integrate correlates of immunogenicity currently available (e.g., PD-L1 expression, TMB, TILs) and help select the subsets of patients who may most benefit from the use of the therapeutic weapons under discussion.

The Neutrophil

Neutrophils are immune cells with unusual biological features that furnish potent antimicrobial properties. These cells phagocytose and subsequently kill prokaryotic and eukaryotic organisms very efficiently. Importantly, it is not only their ability to attack microbes within a constrained intracellular compartment that endows neutrophils with antimicrobial function. They can unleash their effectors into the extracellular space, where, even post-mortem, their killing machinery can endure and remain functional. The antimicrobial activity of neutrophils must not be misconstrued as being microbe specific and should be viewed more generally as biotoxic. Outside of fighting infections, neutrophils can harness their noxious machinery in other contexts, like cancer. Inappropriate or dysregulated neutrophil activation damages the host and contributes to autoimmune and inflammatory disease. Here we review a number of topics related to neutrophil biology based on contemporary findings.

Neutrophil Extracellular Traps in Tumor Metastasis: Pathological Functions and Clinical Applications

Simple Summary

Tumor-associated neutrophils constitute an important portion of the infiltrating immune cells in the tumor microenvironment. One of the abilities of neutrophils is forming neutrophil extracellular traps. Recent studies on tumor-associated neutrophils have drawn increasing attention to the role of neutrophil extracellular traps in the tumor microenvironment. There were also some reviews summarize the pro-tumorigenic activity of NETs in tumors. The specific novelty of this article is the specific summarization on the pivotal roles of NETs in tumor invasion-metastasis cascade and the recapitulation on the potential of NETs in clinical applications.

Abstract

Neutrophil extracellular trap (NET) formation is an ability of neutrophils to capture and kill pathogens by releasing chromatin scaffolds, along with associated cytotoxic enzymes and proteases, into the extracellular space. NETs are usually stimulated by pathogenic microorganisms and their products, surgical pressure or hypoxia. Interestingly, a number of recent studies suggest that tumor cells can induce NET formation, which in turn confers tumor cell malignancy. Notably, emerging studies indicate that NETs are involved in enhancing local invasion, increasing vascular permeability and facilitating immune escape and colonization, thus promoting tumor metastasis. In this article, we review the pivotal roles of NETs in the tumor metastasis cascade. We also recapitulate the potential of NETs as a cancer prognostic biomarker and therapeutic target.

Mechanisms of Ischemic Stroke in Patients with Cancer: A Prospective Study

OBJECTIVE

The objective of this study was to examine the pathophysiology of ischemic stroke with cancer.

METHODS

We conducted a prospective cross-sectional study from 2016 to 2020 at 2 hospitals. We enrolled 3 groups of 50 adult participants each. The main group included patients with active solid tumor cancer and acute ischemic stroke. The control groups included patients with acute ischemic stroke only or active cancer only. The patients with stroke-only and patients with cancer-only were matched to the patients with cancer-plus-stroke by age, sex, and cancer type, if applicable. The outcomes were prespecified hematological biomarkers and transcranial Doppler microemboli detection. Hematological biomarkers included markers of coagulation (D-dimer and thrombin-antithrombin), platelet function (P-selectin), and endothelial integrity (thrombomodulin, soluble intercellular adhesion molecule-1 [sICAM-1], and soluble vascular cell adhesion molecule-1 [sVCAM-1]). Hematological biomarkers were compared between groups using the Kruskal-Wallis and Wilcoxon Rank-Sum tests. In multivariable linear regression models, we adjusted for race, number of stroke risk factors, smoking, stroke severity, and antithrombotic use. Transcranial Doppler microemboli presence was compared between groups using chi-square tests.

RESULTS

Levels of all study biomarkers were different between groups. In univariate between-group comparisons, patients with cancer-plus-stroke had higher levels of D-dimer, sICAM-1, sVCAM-1, and thrombomodulin than both control groups; higher levels of thrombin-antithrombin than patients with cancer-only; and higher levels of P-selectin than patients with stroke-only. Findings were similar in multivariable analyses. Transcranial Doppler microemboli were detected in 32% of patients with cancer-plus-stroke, 16% of patients with stroke-only, and 6% of patients with cancer-only (p = 0.005).

INTERPRETATION

Patients with cancer-related stroke have higher markers of coagulation, platelet, and endothelial dysfunction, and more circulating microemboli, than matched controls. ANN NEUROL 2021;90:159-169.

Neutrophil stimulation with citrullinated histone H4 slows down calcium influx and reduces NET formation compared with native histone H4

Peptidylarginine deiminase 4 (PAD4) catalyzes posttranslational modification of many target proteins through converting protein arginine or mono-methylarginine to citrulline. Neutrophil extracellular trap (NET) formation is the most dramatic manifestation of PAD4-mediated hypercitrullination reaction in neutrophils, which is characterized by the release of nuclear chromatin to form a chromatin network in the extracellular space. Histones H4, one of the major protein components of chromatin, is released into the extracellular space during sepsis, trauma, and ischemia-reperfusion injury and can also be released during the process of NET formation, along with its citrullinated form. The present study showed that histone H4 can induce NET formation in a calcium and PAD4 dependent manner. Histone H4 caused permeabilization of the neutrophil membrane and sustained rise in intracellular calcium that is necessary for activation of PAD4. In comparison, citrullinated histone H4 induced less calcium influx compared with its native form, leading to reduced NET formation. These studies suggest that citrullinated histone H4 could serve as a brake in the pathology of NETs, slowing down the vicious circle between histone H4 and NETs.

Recombinant human DNase I for the treatment of cancer-associated thrombosis: A pre-clinical study

Cancer patients are more likely to develop thrombosis, and this co-morbidity is related to the worse prognosis of the disease. The increased formation of neutrophil extracellular traps (NETs) has been proposed as one of the mechanisms to explain cancer-associated thrombosis. In vivo, degradation of NETs with recombinant human DNase I (rhDNase I) prevents thrombus formation in mouse models. In this work, we evaluated the effect of two different chronic treatments with rhDNase I in a murine NET-dependent prothrombotic state in breast cancer model. Medium-term treatment (2.5 mg/kg rhDNase I for eight consecutive days) did not interfere with the primary growth of 4T1 tumors. On the other hand, it effectively prevented thrombus formation in the inferior vena cava stenosis model. Remarkably, medium-term treatment with rhDNase I showed minor impact in the tail-bleeding model. Different from the medium-term, the long-term treatment with rhDNase I (2.5 mg/kg for 18 successive days) drastically reduced the overall survival. Remarkably, the concomitant use of Ertapenem, a carbapenem antibiotic, and rhDNase I significantly attenuated the mortality observed in the long-term treatment. Our results suggest the therapeutic potential of rhDNase I to treat cancer-associated thrombosis, although its chronic use should be carefully evaluated and potentially harmful.