Neutrophil Extracellular Traps: Villains and Targets in Arterial, Venous, and Cancer-Associated Thrombosis

Duplicated Inferior Vena Cava Thrombosis Mimicking Acute Pancreatitis in a COVID-19 Patient

An 86-year-old woman with a recent hospitalization for severe coronavirus disease 2019 (COVID-19) infection presented to the emergency department with abdominal discomfort and bilateral leg swelling. She was mildly tachycardic on physical exam, with superficial abdominal vessel dilation and bilateral lower extremity edema. Her laboratory results were significant for a mildly elevated lipase of 260 U/L (normal range: 0-160 U/L) and a positive COVID-19 PCR test. CT of the abdomen and pelvis did not show any pancreatic abnormality but revealed a duplicated inferior vena cava (IVC) with a thrombus located in the right IVC. The patient was subsequently placed on full-dose anticoagulation with the eventual achievement of clot lysis. It appears that the incidence of thrombosis, including IVC thrombosis, has been on the rise due to COVID-19-associated coagulopathy; therefore, a high index of clinical suspicion in these cases may prove to be lifesaving.

Neutrophil extracellular traps: A novel target for the treatment of stroke

Stroke is a threatening cerebrovascular disease caused by thrombus with high morbidity and mortality rates. Neutrophils are the first to be recruited in the brain after stroke, which aggravate brain injury through multiple mechanisms. Neutrophil extracellular traps (NETs), as a novel regulatory mechanism of neutrophils, can trap bacteria and secret antimicrobial molecules, thereby degrading pathogenic factors and killing bacteria. However, NETs also exacerbate certain non-infectious diseases by activating autoimmune or inflammatory responses. NETs have been found to play important roles in the pathological process of stroke in recent years. In this review, the mechanisms of NETs formation, the physiological roles of NETs, and the dynamic changes of NETs after stroke are summarized. NETs participate in stroke through various mechanisms. NETs promote the coagulation cascade and interact with platelets to induce thrombosis. tPA induces the degranulation of neutrophils to form NETs, leading to hemorrhagic transformation and thrombolytic resistance. NETs aggravate stroke by mediating inflammation, atherosclerosis and vascular injury. In addition, the regulation of NETs in stroke, the potential of NETs as biomarker and the treatment of stroke targeting NETs are discussed. The increasing evidences suggest that NETs may be a potential target for stroke treatment. Inhibition of NETs formation or promotion of NETs degradation plays protective effects in stroke. However, how to avoid the adverse effects of NETs-targeted therapy deserves further study. In summary, this review provides a reference for the pathogenesis, drug targets, biomarkers and drug development of NETs in stroke.

The Diagnostic Value of the Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio for Deep Venous Thrombosis: A Systematic Review and Meta-Analysis

The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are emerging tools that can be used in the diagnosis of deep venous thrombosis (DVT). This study aims to evaluate the diagnostic value of NLR and PLR for patients with DVT. Our meta-analysis included 11 eligible studies and extracted relevant diagnostic indicators. Of these studies, 4 focused on the NLR, 1 on the PLR, while 6 evaluated both. For the 10 studies on NLR, the pooled sensitivity, specificity, positive-likelihood ratio, and negative-likelihood ratio were 74%, 66%, 2.16, and 0.4, respectively. The estimated diagnostic odds ratio (DOR) was 5.3, and the area under the curve (AUC) of the summary receiver operating characteristic (SROC) curves was 0.74. For the 7 studies on the PLR, the pooled sensitivity, specificity, positive-likelihood ratio, and negative-likelihood ratio were 0.65, 0.77, 2.89, and 0.45, respectively. The estimated DOR was 6.64, and the SROC-AUC was 0.79. Our findings showed that the NLR and PLR exhibit moderate diagnostic accuracy and may be helpful biomarkers for the diagnosis of DVT. Future prospective, well-designed studies with large sample sizes will be required to provide additional evidence to establish cutoff values and clinical value of these indicators.

Neutrophil Extracellular Traps in Cerebral Ischemia/Reperfusion Injury: Friend and Foe

Cerebral ischemic injury, one of the leading causes of morbidity and mortality worldwide, triggers various central nervous system (CNS) diseases, including acute ischemic stroke (AIS) and chronic ischemia-induced Alzheimer's disease (AD). Currently, targeted therapies are urgently needed to address neurological disorders caused by cerebral ischemia/reperfusion injury (CI/RI), and the emergence of neutrophil extracellular traps (NETs) may be able to relieve the pressure. Neutrophils are precursors to brain injury following ischemic stroke and exert complicated functions. NETs extracellularly release reticular complexes of neutrophils, i.e., double-stranded DNA (dsDNA), histones, and granulins. Paradoxically, NETs play a dual role, friend and foe, under different conditions, for example, physiological circumstances, infection, neurodegeneration, and ischemia/reperfusion. Increasing evidence indicates that NETs exert anti-inflammatory effects by degrading cytokines and chemokines through protease at a relatively stable and moderate level under physiological conditions, while excessive amounts of NETs release (NETosis) irritated by CI/RI exacerbate the inflammatory response and aggravate thrombosis, disrupt the blood-brain barrier (BBB), and initiates sequential neuron injury and tissue damage. This review provides a comprehensive overview of the machinery of NETs formation and the role of an abnormal cascade of NETs in CI/RI, as well as other ischemia-induced neurological diseases. Herein, we highlight the potential of NETs as a therapeutic target against ischemic stroke that may inspire translational research and innovative clinical approaches.

Histopathological Features of Cancer-Associated Venous Thromboembolism: Presence of Intrathrombus Cancer Cells and Prothrombotic Factors

BACKGROUND

Cancer-associated venous thromboembolism (VTE) is a critical complication in patients with cancer. However, the pathological findings of VTE are limited. Here, we investigated the histopathological features of cancer-associated VTE in human autopsy cases.

METHODS

We clinically examined the autopsy cases of VTE with (n=114) and without cancer (n=66) and immunohistochemically analyzed the expression of prothrombotic factors in intrathrombus cancer cells, the thrombus contents of erythrocytes, fibrin, platelets, citrullinated histone H3, and degree of organization.

RESULTS

Vascular wall invasion or small cell clusters of cancer cells was observed in thrombi in 27.5% of deep vein thrombosis and 25.9% of pulmonary embolism cases. The majority of the cancer cells in deep vein thrombi appeared to be invading the vessel wall, whereas the majority of pulmonary thrombi had cancer cell clusters, consistent with embolization via blood flow. These cancer cells were immunohistochemically positive for TF (tissue factors) or podoplanin in up to 88% of VTE cases. The frequency of TF-positive monocyte/macrophages in thrombi was higher in cancer-associated VTE than that in VTE without cancer. Citrullinated histone H3 was predominantly observed in the early stages of organizing thrombi. There was no significant difference in thrombus components between VTE with cancer and without cancer groups.

CONCLUSIONS

Vascular wall invasion or cancer cell clusters in thrombi might influence thrombogenesis of cancer-associated VTE. TF and podoplanin in cancer cells and in monocyte/macrophages may induce coagulation reactions and platelet aggregation. Neutrophil extracellular traps may play a role in the early stages of VTE, regardless of cancer status.

Phthalide derivative CD21 regulates the platelet- neutrophil extracellular trap-thrombin axis and protects against ischemic brain injury in rodents

Prothrombotic and proinflammatory properties of neutrophil extracellular traps (NETs) contribute to brain damage after ischemic stroke. CD21 is a novel phthalide neuroprotectant against cerebral ischemia in rodents. This study investigated effects of CD21 on the platelet-NET-thrombin axis and ischemic brain injury and the underlying mechanism. CD21 exerteddose-dependent neuroprotectionin rats that were subjected to2 h middle cerebral artery occlusion,dose-dependentlyinhibited adenosine diphosphate-mediatedplatelet aggregationin rats, and dose-dependentlyexertedanti-thrombotic activityin rodents that received a collagen-epinephrine combination, ferric chloride, or an arteriovenous shunt. Equimolar CD21 doses exerted stronger efficacy than 3-N-butylphthalide (NBP, natural phthalide for the treatment of ischemic stroke). CD21 dose-dependently improved regional cerebral blood flow, neurobehavioral deficits, and infarct volume in mice that were subjected to photothrombotic stroke (PTS). CD21 (13.79 mg/kg, i.v.) significantly decreased NET components (plasma dsDNA concentrations; mRNA levels of elastase, myeloperoxidase, and neutrophil gelatinase-associated lipocalin and protein level of citrullinated histone H3 in ischemic brain tissues), mRNA and protein levels of peptidyl-arginine deiminase 4 (PDA4, NET formation enzyme), and mRNA levels of NET-related inflammatory mediators (interleukin-1β, interleukin-17A, matrix metalloproteinase 8, and matrix metalloproteinase 9) in ischemic brain tissues, despite no effect on mRNA levels of deoxyribonuclease I (NET elimination enzyme). Pretreatment with compound C (inhibitor of adenosine monophosphate-activated protein kinase [AMPK]) significantly reversed the inhibitory effects of CD21 on NETs, PDA4, and inflammatory mediators in PTS mice. These results suggest that CD21 might regulate the platelet-NET-thrombin axis and protect against ischemic brain injury partly through the induction of AMPK activation.

Immune response differences in degradable and non-degradable alloy implants

Alloy based implants have made a great impact in the clinic and in preclinical research. Immune responses are one of the major causes of failure of these implants in the clinic. Although the immune responses toward non-degradable alloy implants are well documented, there is a poor understanding of the immune responses against degradable alloy implants. Recently, there have been several reports suggesting that degradable implants may develop substantial immune responses. This phenomenon needs to be further studied in detail to make the case for the degradable implants to be utilized in clinics. Herein, we review these new recent reports suggesting the role of innate and potentially adaptive immune cells in inducing immune responses against degradable implants. First, we discussed immune responses to allergen components of non-degradable implants to give a better overview on differences in the immune response between non-degradable and degradable implants. Furthermore, we also provide potential areas of research that can be undertaken that may shed light on the local and global immune responses that are generated in response to degradable implants.

Anti-Inflammatory Neutrophil Functions in the Resolution of Inflammation and Tissue Repair

Neutrophils are highly abundant circulating leukocytes that are amongst the first cells to be recruited to sites of infection or sterile injury. Their ability to generate and release powerful cytotoxic products ties with their role in host defence from bacterial and fungal infections. Neutrophilic inflammation is tightly regulated to limit the amount of 'bystander injury' caused. Neutrophils were in the past regarded as short-lived, indiscriminate killers of invading microorganisms. However, this view has changed quite dramatically in recent years. Amongst other insights, neutrophils are now recognised to also have important anti-inflammatory functions that are critical for the resolution of inflammation and return to homeostasis. This minireview focusses on anti-inflammatory neutrophil functions, placing a particular focus on recent findings linked to neutrophil cell death, several types of which may be anti-inflammatory (apoptosis, secondary necrosis, and neutrophil extracellular traps). These are discussed together with features that may further promote the clearance of dead cells by efferocytosis and reprogramming of macrophages to promote resolution and repair.

Methods for the Assessment of NET Formation: From Neutrophil Biology to Translational Research

Several studies have indicated that a neutrophil extracellular trap (NET) formation, apart from its role in host defense, can contribute to or drive pathogenesis in a wide range of inflammatory and thrombotic disorders. Therefore, NETs may serve as a therapeutic target or/and a diagnostic tool. Here, we compare the most commonly used techniques for the assessment of NET formation. Furthermore, we review recent data from the literature on the application of basic laboratory tools for detecting NET release and discuss the challenges and the advantages of these strategies in NET evaluation. Taken together, we provide some important insights into the qualitative and quantitative molecular analysis of NETs in translational medicine today.

Role of neutrophil extracellular traps in inflammatory evolution in severe acute pancreatitis

ABSTRACT

Severe acute pancreatitis (SAP) is a life-threatening acute abdominal disease with two peaks of death: the first in the early stage, characterized by systemic inflammatory response-associated organ failure; and the second in the late stage, characterized by infectious complications. Neutrophils are the main immune cells participating in the whole process of SAP. In addition to the traditional recognition of neutrophils as the origination of chemokine and cytokine cascades or phagocytosis and degranulation of pathogens, neutrophil extracellular traps (NETs) also play an important roles in inflammatory reactions. We reviewed the role of NETs in the occurrence and development of SAP and its fatal complications, including multiple organs injury, infected pancreatic necrosis, and thrombosis. This review provides novel insights into the involvement of NETs throughout the entire process of SAP, showing that targeting NETs might be a promising strategy in SAP treatment. However, precision therapeutic options targeting NETs in different situations require further investigation.

Anti-cardiolipin IgG autoantibodies associate with circulating extracellular DNA in severe COVID-19

Whereas the detection of antiphospholipid autoantibodies (aPL) in COVID-19 is of increasing interest, their role is still unclear. We analyzed a large aPL panel in 157 patients with COVID-19 according to the disease severity. We also investigated a potential association between aPL and extracellular DNA (exDNA, n = 85) or circulating markers of neutrophil extracellular traps (NET) such as citrullinated histones H3 (CitH3, n = 49). A total of 157 sera of patients infected by SARS-CoV-2 were collected. A large aPL panel including lupus anticoagulant, anti-cardiolipin and anti-beta-2 glycoprotein I (IgG, IgM and IgA), anti-phosphatidylethanolamine IgA, anti-prothrombin (IgG and IgM) was retrospectively analyzed according to the disease severity. We found a total aPL prevalence of 54.8% with almost half of the cases having aCL IgG. Within an extended panel of aPL, only aCL IgG were associated with COVID-19 severity. Additionally, severe patients displayed higher CitH3 levels than mild patients. Interestingly, we highlighted a significant association between the levels of aCL IgG and exDNA only in aCL positive patients with severe disease. In conclusion, we showed a significant link between aPL, namely aCL IgG, and circulating exDNA in patients with severe form of COVID-19, that could exacerbate the thrombo-inflammatory state related to disease severity.

There is urgent need to treat atherosclerotic cardiovascular disease risk earlier, more intensively, and with greater precision: A review of current practice and recommendations for improved effectiveness

Atherosclerotic cardiovascular disease (ASCVD) is epidemic throughout the world and is etiologic for such acute cardiovascular events as myocardial infarction, ischemic stroke, unstable angina, and death. ASCVD also impacts risk for dementia, chronic kidney disease peripheral arterial disease and mobility, impaired sexual response, and a host of other visceral impairments that adversely impact the quality and rate of progression of aging. The relationship between low-density lipoprotein cholesterol (LDL-C) and risk for ASCVD is one of the most highly established and investigated issues in the entirety of modern medicine. Elevated LDL-C is a necessary condition for atherogenesis induction. Basic scientific investigation, prospective longitudinal cohorts, and randomized clinical trials have all validated this association. Yet despite the enormous number of clinical trials which support the need for reducing the burden of atherogenic lipoprotein in blood, the percentage of high and very high-risk patients who achieve risk stratified LDL-C target reductions is low and has remained low for the last thirty years. Atherosclerosis is a preventable disease. As clinicians, the time has come for us to take primordial and primary prevention more serously. Despite a plethora of therapeutic approaches, the large majority of patients at risk for ASCVD are poorly or inadequately treated, leaving them vulnerable to disease progression, acute cardiovascular events, and poor aging due to loss of function in multiple visceral organs. Herein we discuss the need to greatly intensify efforts to reduce risk, decrease disease burden, and provide more comprehensive and earlier risk assessment to optimally prevent ASCVD and its complications. Evidence is presented to support that treatment should aim for far lower goals in cholesterol management, should take into account many more factors than commonly employed today and should begin significantly earlier in life.

Molecular insight into pentraxin-3: Update advances in innate immunity, inflammation, tissue remodeling, diseases, and drug role

Pentraxin-3 (PTX3) is the prototype of the long pentraxin subfamily, an acute-phase protein consisting of a C-terminal pentraxin domain and a unique N-terminal domain. PTX3 was initially isolated from human umbilical vein endothelial cells and human FS-4 fibroblasts. It was subsequently found to be also produced by synoviocytes, chondrocytes, osteoblasts, smooth muscle cells, myeloid dendritic cells, epithelial cells, and tumor cells. Various modulatory factors, such as miRNAs, cytokines, drugs, and hypoxic conditions, could regulate the expression level of PTX3. PTX3 is essential in regulating innate immunity, inflammation, angiogenesis, and tissue remodeling. Besides, PTX3 may play dual (pro-tumor and anti-tumor) roles in oncogenesis. PTX3 is involved in the occurrence and development of many non-cancerous diseases, including COVID-19, and might be a potential biomarker indicating the prognosis, activity,and severity of diseases. In this review, we summarize and discuss the potential roles of PTX3 in the oncogenesis and pathogenesis of non-cancerous diseases and potential targeted therapies based on PTX3.

Neutrophil extracellular traps and complications of liver transplantation

Many end-stage liver disease etiologies are attributed to robust inflammatory cell recruitment. Neutrophils play an important role in inflammatory infiltration and neutrophil phagocytosis, oxidative burst, and degranulation. It has also been suggested that neutrophils may release neutrophil extracellular traps (NETs) to kill pathogens. It has been proven that neutrophil infiltration within the liver contributes to an inflammatory microenvironment and immune cell activation. Growing evidence implies that NETs are involved in the progression of numerous complications of liver transplantation, including ischemia-reperfusion injury, acute rejection, thrombosis, and hepatocellular carcinoma recurrence. NETs are discussed in this comprehensive review, focusing on their effects on liver transplantation complications. Furthermore, we discuss NETs as potential targets for liver transplantation therapy.

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

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

Neutrophil Recruitment in Arterial Thrombus and Characteristics of Stroke Patients with Neutrophil-Rich Thrombus

PURPOSE

Neutrophils contribute to thrombosis. However, there is limited information on the temporal course of neutrophil recruitment in thrombosis, the contribution of neutrophils to thrombus growth, and the characteristics of stroke patients with neutrophil-rich thrombi.

MATERIALS AND METHODS

After inducing carotid artery thrombosis in Institute of Cancer Research mice using ferric chloride, aged thrombi were produced by ligating the distal portion of the carotid artery in mice for 0.5, 1, 2, 3, 6, or 24 h. For thrombus analysis in stroke patients, we used registry data and thrombi that were obtained during intra-arterial thrombectomy. Immunohistochemistry was performed to determine thrombus composition.

RESULTS

In the thrombi of 70 mice, Ly6G positive cell counts (neutrophils) and histone H3-positive cell counts increased in a time-dependent manner (both p<0.001). Ly6G-positive cell count was strongly correlated with histone H3-positive cell counts (r=0.910, p<0.001), but not with thrombus size (p=0.320). In 75 stroke patients, atrial fibrillation and cardioembolism were more frequent in the higher neutrophil group (32/37, 86.5%) than in the lower neutrophil group (19/38, 50%) (p=0.002). The median erythrocyte fraction was higher [52.0 (interquartile range 39.9-57.8)] in the higher neutrophil group than in the lower neutrophil group [40.3 (interquartile range 23.5-53.2)]. The fraction of neutrophils was positively correlated with that of erythrocytes (R=0.35, p=0.002).

CONCLUSION

Neutrophils were recruited and increased in arterial thrombosis in a time-dependent manner; however, they were not associated with the growth of formed thrombi. Neutrophil fractions in the thrombi of stroke patients appeared to be associated with atrial fibrillation and erythrocyte fraction.

Bibliometric and visual analysis of neutrophil extracellular traps from 2004 to 2022

Background

Neutrophil extracellular traps (NETs) are specialized structures formed by neutrophils that were initially found to be important in killing pathogenic bacteria during infection. With the development of related research, the relationship between NETs and diseases such as sepsis, cancer, and systemic lupus erythematosus has received close attention. However, there is a lack of reports that comprehensively and objectively present the current status of NETs-related studies. Therefore, this study aims to visually analyze the current status and trends of NETs-related research by means of bibliometrics and knowledge mapping.

Methods

NETs-related articles and reviews were retrieved using the Web of Science core collection subject search, and bibliometric analysis was performed in Excel 365, CiteSpace, VOSviewer, and Bibliometrix (R-Tool of R-Studio).

Results

A total of 4866 publications from 2004 to 2022 were included in the bibliometric analysis. The number of publications shows an increasing trend from year to year. Collaborative network analysis shows that the United States and Germany are the most influential countries in this field, with the highest number of publications and citations. The journal with the most publications is Frontiers in Immunology. Brinkmann Volker is an authoritative author in this field, and his publication "Neutrophil extracellular traps kill bacteria" is the most frequently cited. The literature and keyword analysis shows that the relationship between NETs and diseases (hematological diseases, sepsis, cancer, etc.) and cell death (apoptosis, necroptosis, pyroptosis, etc.) is a popular research topic. Currently, NETs and SARS-CoV-2-related studies are at the forefront of the field.

Conclusion

This study is the first to visualize the research in NETs-related fields using bibliometric methods, revealing the trends and frontiers of NETs research. This study will provide valuable references for scholars to find research focus questions and partners.

Cellular Landscaping of COVID-19 and Gynaecological Cancers: An Infrequent Correlation

COVID-19 resulted in a mortality rate of 3-6% caused by SARS-CoV-2 and its variant leading to unprecedented consequences of acute respiratory distress septic shock and multiorgan failure. In such a situation, evaluation, diagnosis, treatment, and care for cancer patients are difficult tasks faced by medical staff. Moreover, patients with gynaecological cancer appear to be more prone to severe infection and mortality from COVID-19 due to immunosuppression by chemotherapy and coexisting medical disorders. To deal with such a circumtances oncologists have been obliged to reconsider the entire diagnostic, treatment, and management approach. This review will provide and discuss the molecular link with gynaecological cancer under COVID-19 infection, providing a novel bilateral relationship between the two infections. Moreover, the authors have provided insights to discuss the pathobiology of COVID-19 in gynaecological cancer and their risks associated with such comorbidity. Furthermore, we have depicted the overall impact of host immunity along with guidelines for the treatment of patients with gynaecological cancer under COVID-19 infection. We have also discussed the feasible scope for the management of COVID-19 and gynaecological cancer.

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.

Interleukin-1 and the NLRP3 inflammasome in COVID-19: Pathogenetic and therapeutic implications

A hyperinflammatory response during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection crucially worsens clinical evolution of coronavirus disease 2019 (COVID-19). The interaction between SARS-CoV-2 and angiotensin-converting enzyme 2 (ACE2) triggers the activation of the NACHT, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome. Enhanced inflammasome activity has been associated with increased disease severity and poor prognosis. Evidence suggests that inflammasome activation and interleukin-1β (IL-1β) release aggravate pulmonary injury and induce hypercoagulability, favoring progression to respiratory failure and widespread thrombosis eventually leading to multiorgan failure and death. Observational studies with the IL-1 blockers anakinra and canakinumab provided promising results. In the SAVE-MORE trial, early treatment with anakinra significantly shortened hospital stay and improved survival in patients with moderate-to-severe COVID-19. In this review, we summarize current evidence supporting the pathogenetic role of the NLRP3 inflammasome and IL-1β in COVID-19, and discuss clinical trials testing IL-1 inhibition in COVID-19.

Venous thromboembolism in cancer and cancer immunotherapy

Venous thromboembolism (VTE) is a clinical disease that includes deep vein thrombosis and pulmonary embolism. Amongst its underlying risk factors, cancer is of great importance. Stasis, endothelial injury, and hypercoagulability result in clot formation and VTE. Cancer can affect coagulability by favoring these three factors, resulting in VTE incidence. Immunotherapy is a novel therapeutic approach, targeting cancer by immune system enhancement. VTE is one of the most important adverse effects of immunotherapy, which complicates the administration of immunotherapy in cancer patients. The current review provides a brief overview of VTE epidemiology, pathophysiology, risk factors, biomarkers, the relationship of cancer and cancer immunotherapy to VTE incidence, and managing cancer-associated VTE.

The Gab2-MALT1 axis regulates thromboinflammation and deep vein thrombosis

Deep vein thrombosis (DVT) is the third most common cause of cardiovascular mortality. Several studies suggest that DVT occurs at the intersection of dysregulated inflammation and coagulation upon activation of inflammasome and secretion of interleukin 1β (IL-1β) in restricted venous flow conditions. Our recent studies showed a signaling adapter protein, Gab2 (Grb2-associated binder 2), plays a crucial role in propagating inflammatory signaling triggered by IL-1β and other inflammatory mediators in endothelial cells. The present study shows that Gab2 facilitates the assembly of the CBM (CARMA3 [CARD recruited membrane-associated guanylate kinase protein 3]-BCL-10 [B-cell lymphoma 10]-MALT1 [mucosa-associated lymphoid tissue lymphoma translocation protein 1]) signalosome, which mediates the activation of Rho and NF-κB in endothelial cells. Gene silencing of Gab2 or MALT1, the effector signaling molecule in the CBM signalosome, or pharmacological inhibition of MALT1 with a specific inhibitor, mepazine, significantly reduced IL-1β-induced Rho-dependent exocytosis of P-selectin and von Willebrand factor (VWF) and the subsequent adhesion of neutrophils to endothelial cells. MALT1 inhibition also reduced IL-1β-induced NF-κB-dependent expression of tissue factor and vascular cell adhesion molecule 1. Consistent with the in vitro data, Gab2 deficiency or pharmacological inhibition of MALT1 suppressed the accumulation of monocytes and neutrophils at the injury site and attenuated venous thrombosis induced by the inferior vena cava ligation-induced stenosis or stasis in mice. Overall, our data reveal a previously unrecognized role of the Gab2-MALT1 axis in thromboinflammation. Targeting the Gab2-MALT1 axis with MALT1 inhibitors may become an effective strategy to treat DVT by suppressing thromboinflammation without inducing bleeding complications.

Extracellular vesicles and particles impact the systemic landscape of cancer

Intercellular cross talk between cancer cells and stromal and immune cells is essential for tumor progression and metastasis. Extracellular vesicles and particles (EVPs) are a heterogeneous class of secreted messengers that carry bioactive molecules and that have been shown to be crucial for this cell-cell communication. Here, we highlight the multifaceted roles of EVPs in cancer. Functionally, transfer of EVP cargo between cells influences tumor cell growth and invasion, alters immune cell composition and function, and contributes to stromal cell activation. These EVP-mediated changes impact local tumor progression, foster cultivation of pre-metastatic niches at distant organ-specific sites, and mediate systemic effects of cancer. Furthermore, we discuss how exploiting the highly selective enrichment of molecules within EVPs has profound implications for advancing diagnostic and prognostic biomarker development and for improving therapy delivery in cancer patients. Altogether, these investigations into the role of EVPs in cancer have led to discoveries that hold great promise for improving cancer patient care and outcome.

NETosis and thrombosis in vaccine-induced immune thrombotic thrombocytopenia

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare yet serious adverse effect of the adenoviral vector vaccines ChAdOx1 nCoV-19 (AstraZeneca) and Ad26.COV2.S (Janssen) against COVID-19. The mechanisms involved in clot formation and thrombocytopenia in VITT are yet to be fully determined. Here we show neutrophils undergoing NETosis and confirm expression markers of NETs in VITT patients. VITT antibodies directly stimulate neutrophils to release NETs and induce thrombus formation containing abundant platelets, neutrophils, fibrin, extracellular DNA and citrullinated histone H3 in a flow microfluidics system and in vivo. Inhibition of NETosis prevents VITT-induced thrombosis in mice but not thrombocytopenia. In contrast, in vivo blockage of FcγRIIa abrogates both thrombosis and thrombocytopenia suggesting these are distinct processes. Our findings indicate that anti-PF4 antibodies activate blood cells via FcγRIIa and are responsible for thrombosis and thrombocytopenia in VITT. Future development of NETosis and FcγRIIa inhibitors are needed to treat VITT and similar immune thrombotic thrombocytopenia conditions more effectively, leading to better patient outcomes.

The mechanisms underlying the pathogenesis of vaccine-induced immune thrombotic thrombocytopenia (VITT) remain unclear. Here the authors show that anti-PF4 antibodies are responsible for the activation of platelets and neutrophils, and blockage of FcγRIIa or NETosis in vivo can prevent thrombosis.

Fibrin structure, viscoelasticity and lysis face the interplay of biorelevant polyions

PURPOSE OF REVIEW

In the past 5 decades, heparins have been widely used as anticoagulants in the prevention and treatment of thrombosis. Subsequent development of heparin variants of various size and charge facilitated the discovery of their multiple biological actions and nonanticoagulant benefits. Platelet-derived or microbial polyphosphates, as well as DNA released in the course of neutrophil extracellular trap-formation are additional polyanions, which can modulate the development and stability of thrombi associated with cancer or inflammation. In this review, we focus on the size-dependent and electric charge-dependent modulatory effects of the three polyanions of different chemical structure.

RECENT FINDINGS

The polycationic histones have been recognized as potential biomarkers and therapeutic targets in several diseases related to inflammation and thrombosis. Since combating histones with activated protein C or heparin could cause unwanted bleeding, the quest for nonanticoagulant histone-neutralizing agents is ongoing. Polyanions may neutralize or exaggerate certain histone-mediated effects depending on their electric charge, size and histone effects under investigation. Several prothrombotic effects of polyphosphates and DNA are also size-dependent.

SUMMARY

The efficiency of future therapeutics targeting prothrombotic polyanions or histones is not a simple matter of electric charge, but may rely on a delicate combination of size, charge and chemical composition.

The role of B cells in COVID-19 infection and vaccination

B cells secrete antibodies and mediate the humoral immune response, making them extremely important in protective immunity against SARS-CoV-2, which caused the coronavirus disease 2019 (COVID-19) pandemic. In this review, we summarize the positive function and pathological response of B cells in SARS-CoV-2 infection and re-infection. Then, we structure the immunity responses that B cells mediated in peripheral tissues. Furthermore, we discuss the role of B cells during vaccination including the effectiveness of antibodies and memory B cells, viral evolution mechanisms, and future vaccine development. This review might help medical workers and researchers to have a better understanding of the interaction between B cells and SARS-CoV-2 and broaden their vision for future investigations.

Extracellular traps and the role in thrombosis

Thrombotic complications pose serious health risks worldwide. A significant change in our understanding of the pathophysiology of thrombosis has occurred since the discovery of extracellular traps (ETs) and their prothrombotic properties. As a result of immune cells decondensing chromatin into extracellular fibers, ETs promote thrombus formation by acting as a scaffold that activates platelets and coagulates them. The involvement of ETs in thrombosis has been reported in various thrombotic conditions including deep vein thrombosis (DVT), pulmonary emboli, acute myocardial infarction, aucte ischemic stroke, and abdominal aortic aneurysms. This review summarizes the existing evidence of ETs in human and animal model thrombi. The authors described studies showing the existence of ETs in venous or arterial thrombi. In addition, we studied potential novel therapeutic opportunities related to the resolution or prevention of thrombosis by targeting ETs.

Determinants of Endogenous Fibrinolysis in Whole Blood Under High Shear in Patients With Myocardial Infarction

Hypofibrinolysis is a recently-recognized risk factor for recurrent cardiovascular events in patients with ST-segment elevation myocardial infarction (STEMI), but the mechanistic determinants of this are not well understood. In patients with STEMI, we show that the effectiveness of endogenous fibrinolysis in whole blood is determined in part by fibrinogen level, high sensitivity C-reactive protein, and shear-induced platelet reactivity, the latter directly related to the speed of thrombin generation. Our findings strengthen the evidence for the role of cellular components and bidirectional crosstalk between coagulatory and inflammatory pathways as determinants of hypofibrinolysis.

Consensus clustering of gene expression profiles in peripheral blood of acute ischemic stroke patients

Acute ischemic stroke (AIS) is a primary cause of mortality and morbidity worldwide. Currently, no clinically approved immune intervention is available for AIS treatment, partly due to the lack of relevant patient classification based on the peripheral immunity status of patients with AIS. In this study, we adopted the consensus clustering approach to classify patients with AIS into molecular subgroups based on the transcriptomic profiles of peripheral blood, and we identified three distinct AIS molecular subgroups and 8 modules in each subgroup by the weighted gene co-expression network analysis. Remarkably, the pre-ranked gene set enrichment analysis revealed that the co-expression modules with subgroup I-specific signature genes significantly overlapped with the differentially expressed genes in AIS patients with hemorrhagic transformation (HT). With respect to subgroup II, exclusively male patients with decreased proteasome activity were identified. Intriguingly, the majority of subgroup III was composed of female patients who showed a comparatively lower level of AIS-induced immunosuppression (AIIS). In addition, we discovered a non-linear relationship between female age and subgroup-specific gene expression, suggesting a gender- and age-dependent alteration of peripheral immunity. Taken together, our novel AIS classification approach could facilitate immunomodulatory therapies, including the administration of gender-specific therapeutics, and attenuation of the risk of HT and AIIS after ischemic stroke.

Chromatin-Associated Molecular Patterns (CAMPs) in sepsis

Several molecular patterns have been identified that recognize pattern recognition receptors. Pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) are commonly used terminologies to classify molecules originating from pathogen and endogenous molecules, respectively, to heighten the immune response in sepsis. Herein, we focus on a subgroup of endogenous molecules that may be detected as foreign and similarly trigger immune signaling pathways. These chromatin-associated molecules, i.e., chromatin containing nuclear DNA and histones, extracellular RNA, mitochondrial DNA, telomeric repeat-containing RNA, DNA- or RNA-binding proteins, and extracellular traps, may be newly classified as chromatin-associated molecular patterns (CAMPs). Herein, we review the release of CAMPs from cells, their mechanism of action and downstream immune signaling pathways, and targeted therapeutic approaches to mitigate inflammation and tissue injury in inflammation and sepsis.

The Effect of Paracrine Factors Released by Irradiated Peripheral Blood Mononuclear Cells on Neutrophil Extracellular Trap Formation

Neutrophil extracellular trap (NET)-formation represents an important defence mechanism for the rapid clearance of infections. However, exaggerated NET formation has been shown to negatively affect tissue-regeneration after injury. As our previous studies revealed the strong tissue-protective and regenerative properties of the secretome of stressed peripheral blood mononuclear cells (PBMCsec), we here investigated the influence of PBMCsec on the formation of NETs. The effect of PBMCsec on NET formation was assessed ex vivo in ionomycin stimulated neutrophils derived from healthy donors using flow cytometry, image stream analysis, and quantification of released extracellular DNA. The effect of PBMCsec on molecular mechanisms involved in NET formation, including Ca-flux, protein kinase C activity, reactive oxygen species production, and protein arginine deiminase 4 activity, were analysed. Our results showed that PBMCsec significantly inhibited NET formation. Investigation of the different biological substance classes found in PBMCsec revealed only a partial reduction in NET formation, suggesting a synergistic effect. Mechanistically, PBMCsec treatment did not interfere with calcium signalling and PKC-activation, but exerted anti-oxidant activity, as evidenced by reduced levels of reactive oxygen species and upregulation of heme oxygenase 1 and hypoxia inducible-factor 1 in PBMCsec-treated neutrophils. In addition, PBMCsec strongly inhibited the activation of protein arginine deiminase 4 (PAD4), ultimately leading to the inhibition of NET formation. As therapeutics antagonizing excessive NET formation are not currently available, our study provides a promising novel treatment option for a variety of conditions resulting from exaggerated NET formation.

The interplay between inflammation and thrombosis in COVID-19: Mechanisms, therapeutic strategies, and challenges

Coronavirus disease 2019 (COVID-19), caused by a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can cause life-threatening pathology characterized by a dysregulated immune response and coagulopathy. While respiratory failure induced by inflammation is the most common cause of death, micro-and macrovascular thrombosis leading to multiple organ failure are also causes of mortality. Dysregulation of systemic inflammation observed in severe COVID-19 patients is manifested by cytokine release syndrome (CRS) - the aberrant release of high levels of proinflammatory cytokines, such as IL-6, IL-1, TNFα, MP-1, as well as complement. CRS is often accompanied by activation of endothelial cells and platelets, coupled with perturbation of the balance between the pro-and antithrombotic mechanisms, resulting in thrombosis. Inflammation and thrombosis form a vicious circle, contributing to morbidity and mortality. Treatment of hyperinflammation has been shown to decrease thrombosis, while anti-thrombotic treatment also downregulates cytokine release. This review highlights the relationship between COVID-19-mediated systemic inflammation and thrombosis, the molecular pathways involved, the therapies targeting these processes, and the challenges currently encountered.

Neutrophils and Neutrophil Extracellular Traps in Cardiovascular Disease: An Overview and Potential Therapeutic Approaches

Recent advances in pharmacotherapy have markedly improved the prognosis of cardiovascular disease (CVD) but have not completely conquered it. Therapies targeting the NOD-like receptor family pyrin domain containing 3 inflammasome and its downstream cytokines have proven effective in the secondary prevention of cardiovascular events, suggesting that inflammation is a target for treating residual risk in CVD. Neutrophil-induced inflammation has long been recognized as important in the pathogenesis of CVD. Circadian rhythm-related and disease-specific microenvironment changes give rise to neutrophil diversity. Neutrophils are primed by various stimuli, such as chemokines, cytokines, and damage-related molecular patterns, and the activated neutrophils contribute to the inflammatory response in CVD through degranulation, phagocytosis, reactive oxygen species generation, and the release of neutrophil extracellular traps (NETs). In particular, NETs promote immunothrombosis through the interaction with vascular endothelial cells and platelets and are implicated in the development of various types of CVD, such as acute coronary syndrome, deep vein thrombosis, and heart failure. NETs are promising candidates for anti-inflammatory therapy in CVD, and their efficacy has already been demonstrated in various animal models of the disease; however, they have yet to be clinically applied in humans. This narrative review discusses the diversity and complexity of neutrophils in the trajectory of CVD, the therapeutic potential of targeting NETs, and the related clinical issues.

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

Background

Venous thromboembolism (VTE) diagnosis would greatly benefit from the identification of novel biomarkers to complement D-dimer, a marker limited by low specificity. Neutrophil extracellular traps (NETs) have been shown to promote thrombosis and could hypothetically be used for diagnosis of acute VTE.

Objectives

To assess the levels of specific markers of neutrophil activation and NETs and compare their diagnostic accuracy to D-dimer.

Methods

We measured plasma levels of neutrophil activation marker neutrophil elastase (NE), the NET marker nucleosomal citrullinated histone H3 (H3Cit-DNA) and cell-free DNA in patients (n = 294) with suspected VTE (pulmonary embolism and deep vein thrombosis) as well as healthy controls (n = 30). A total of 112 VTE positive and 182 VTE negative patients from two prospective cohort studies were included.

Results

Higher levels of H3Cit-DNA and NE, but not cell-free DNA, were associated with VTE. Area under receiver operating curves (AUC) were 0.90 and 0.93 for D-dimer, 0.65 and 0.68 for NE and 0.60 and 0.67 for H3Cit-DNA in the respective cohorts. Adding NE and H3Cit-DNA to a D-dimer based risk model did not improve AUC.

Conclusions

Our study demonstrates the presence of neutrophil activation and NET formation in VTE using specific markers. However, the addition of NE or H3Cit-DNA to D-dimer did not improve the discrimination compared to D-dimer alone. This study provides information on the feasibility of using markers of NETs as diagnostic tools in acute VTE. Based on our findings, we believe the potential of these markers are limited in this setting.

Neutrophil Extracellular Traps Promote NLRP3 Inflammasome Activation and Glomerular Endothelial Dysfunction in Diabetic Kidney Disease

Diabetes mellitus is a metabolic disease largely due to lifestyle and nutritional imbalance, resulting in insulin resistance, hyperglycemia and vascular complications. Diabetic kidney disease (DKD) is a major cause of end-stage renal failure contributing to morbidity and mortality worldwide. Therapeutic options to prevent or reverse DKD progression are limited. Endothelial and glomerular filtration barrier (GFB) dysfunction and sterile inflammation are associated with DKD. Neutrophil extracellular traps (NETs), originally identified as an innate immune mechanism to combat infection, have been implicated in sterile inflammatory responses in non-communicable diseases. However, the contribution of NETs in DKD remains unknown. Here, we show that biomarkers of NETs are increased in diabetic mice and diabetic patients and that these changes correlate with DKD severity. Mechanistically, NETs promote NLRP3 inflammasome activation and glomerular endothelial dysfunction under high glucose stress in vitro and in vivo. Inhibition of NETs (PAD4 inhibitor) ameliorate endothelial dysfunction and renal injury in DKD. Taken together, NET-induced sterile inflammation promotes diabetes-associated endothelial dysfunction, identifying a new pathomechanism contributing to DKD. Inhibition of NETs may be a promising therapeutic strategy in DKD.

Neutrophil extracellular traps participate in the development of cancer-associated thrombosis in patients with gastric cancer

BACKGROUND

The development of venous thromboembolism (VTE) is associated with high mortality among gastric cancer (GC) patients. Neutrophil extracellular traps (NETs) have been reported to correlate with the prothrombotic state in some diseases, but are rarely reported in GC patients.

AIM

To investigate the effect of NETs on the development of cancer-associated thrombosis in GC patients.

METHODS

The levels of NETs in blood and tissue samples of patients were analyzed by ELISA, flow cytometry, and immunofluorescence staining. NET generation and hypercoagulation of platelets and endothelial cells (ECs) in vitro were observed by immunofluorescence staining. NET procoagulant activity (PCA) was determined by fibrin formation and thrombin–antithrombin complex (TAT) assays. Thrombosis in vivo was measured in a murine model induced by flow stenosis in the inferior vena cava (IVC).

RESULTS

NETs were likely to form in blood and tissue samples of GC patients compared with healthy individuals. In vitro studies showed that GC cells and their conditioned medium, but not gastric mucosal epithelial cells, stimulated NET release from neutrophils. In addition, NETs induced a hypercoagulable state of platelets by upregulating the expression of phosphatidylserine and P-selectin on the cells. Furthermore, NETs stimulated the adhesion of normal platelets on glass surfaces. Similarly, NETs triggered the conversion of ECs to hypercoagulable phenotypes by downregulating the expression of their intercellular tight junctions but upregulating that of tissue factor. Treatment of normal platelets or ECs with NETs augmented the level of plasma fibrin formation and the TAT complex. In the models of IVC stenosis, tumor-bearing mice showed a stronger ability to form thrombi, and NETs abundantly accumulated in the thrombi of tumor-bearing mice compared with control mice. Notably, the combination of deoxyribonuclease I, activated protein C, and sivelestat markedly abolished the PCA of NETs.

CONCLUSION

GC-induced NETs strongly increased the risk of VTE development both in vitro and in vivo. NETs are potential therapeutic targets in the prevention and treatment of VTE in GC patients.

Venous Thromboembolism in Sepsis: From Bench to Bedside

Septic patients were commonly affected by coagulation disorders; thus, they are at high risk of thrombotic complications. In the last decades, novel knowledge has emerged about the interconnected and reciprocal influence of immune and coagulation systems. This phenomenon is called immunothrombosis, and it indicates an effective response whereby immune cells and the coagulation cascade cooperate to limit pathogen invasion and endothelial damage. When this network becomes dysregulated due to a systemic inflammatory activation, as occurs during sepsis, it can result in pathological thrombosis. Endothelium, platelets and neutrophils are the main characters involved in this process, together with the TF and coagulation cascade, playing a critical role in both the host defense and in thrombogenesis. A deeper understanding of this relationship may allow us to answer the growing need for clinical instruments to establish the thrombotic risk and treatments that consider more the connection between coagulation and inflammation. Heparin remains the principal therapeutical response to this phenomenon, although not sufficiently effective. To date, no other significant alternatives have been found yet. In this review, we discuss the role of sepsis-related inflammation in the development and resolution of venous thromboembolism and its clinical implications, from bench to bedside.

Elevated risk of thrombotic manifestations of SARS-CoV-2 infection in cancer patients: A literature review

Coronavirus disease 2019 (COVID-19) results in higher risks of hospitalization or death in older patients and those with multiple comorbidities, including malignancies. Patients with cancer have greater risks of COVID-19 onset and worse prognosis. This excess is mainly explained by thrombotic complications. Indeed, an imbalance in the equilibrium between clot formation and bleeding, increased activation of coagulation, and endothelial dysfunction characterize both COVID-19 patients and those with cancer. With this review, we provide a summary of the pathological mechanisms of coagulation and thrombotic manifestations in these patients and discuss the possible therapeutic implications of these phenomena.

The Significance of Neutrophil Extracellular Traps in Colorectal Cancer and Beyond: From Bench to Bedside

Neutrophil extracellular traps (NETs), products of neutrophil death when exposed to certain stimuli, were first proposed as a type of response to bacterial infection in infectious diseases. Since then, extensive studies have discovered its involvement in other non-infectious inflammatory diseases including thromboembolism, autoimmune diseases, and cancer. Colorectal cancer (CRC) is one of the most common malignancies in the world. NET formation is closely associated with tumorigenesis, progression, and metastasis in CRC. Therefore, the application of NETs in clinical practice as diagnostic biomarkers, therapeutic targets, and prognostic predictors has a promising prospect. In addition, therapeutics targeting NETs are significantly efficient in halting tumor progression in preclinical cancer models, which further indicates its potential clinical utility in cancer treatment. This review focuses on the stimuli of NETosis, its pro-tumorigenic activity, and prospective clinical utility primarily in but not limited to CRC.

Impact of Neutrophil Extracellular Traps on Thrombosis Formation: New Findings and Future Perspective

Thrombotic diseases seriously endanger human health, neutrophils and neutrophil extracellular traps (NETs) play an important role in abnormal thrombus formation. NETs are extracellular structures released by neutrophils upon stimulation by pathogens. NETs include neutrophil elastase (NE), myeloperoxidase (MPO), cathepsin G and other active substances. The network structure provided by NETs can prevent the spread of pathogens and effectively kill and eliminate pathogens. However, the components of NETs can also abnormally activate the coagulation pathway and participate in the formation of pathological thrombi. This review aims to summarize the mechanisms of NETs formation in detail; the research progress of NETs in venous thrombosis, arterial thrombosis, acquired disease-associated thrombosis, sepsis coagulation disorder; as well as the strategies to target NETs in thrombosis prevention and treatment.

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.

Thrombosis, cancer, and COVID-19

Cancer and coronavirus disease 2019 (COVID-19) have unusual similarities: they both result in a markedly elevated risk of thrombosis, exceptionally high D-dimer levels, and the failure of anticoagulation therapy in some cases. Cancer patients are more vulnerable to COVID-19 infection and have a higher mortality rate. Science has uncovered much about SARS-CoV-2, and made extraordinary and unprecedented progress on the development of various treatment strategies and COVID-19 vaccines. In this review, we discuss known data on cancer-associated thrombosis (CAT), SARS-CoV-2 infection, and COVID-19 vaccines and discuss considerations for managing CAT in patients with COVID-19. Cancer patients should be given priority for COVID-19 vaccination; however, they may demonstrate a weaker immune response to COVID-19 vaccines than the general population. Currently, the Centers for Disease Control and Prevention recommends an additional dose and booster shot of the COVID-19 vaccine after the primary series in patients undergoing active cancer treatment for solid tumors or hematological cancers, recipients of stem cell transplant within the last 2 years, those taking immunosuppressive medications, and those undergoing active treatment with high-dose corticosteroids or other drugs that suppress the immune response. The mainstay of thrombosis treatment in patients with cancer and COVID-19 is anticoagulation therapy.

Neutrophil extracellular traps are associated with enhanced procoagulant activity in liver cirrhosis patients with portal vein thrombosis

OBJECTIVE

Patients with liver cirrhosis (LC) commonly exhibit hypercoagulability and tend to develop thrombosis. Neutrophil extracellular traps (NETs) are associated with a variety of thrombotic conditions, but their possible value in portal vein thrombosis (PVT) is not known. We assessed whether NETs promote thrombosis and contribute to the procoagulant state in patients with LC.

METHODS

The circulating levels of NETs markers (myeloperoxidase, neutrophil elastase, citrullinated histone H3) were measured in 72 patients (median age, 55 years; 48 [66.7%] men) with LC from September 2020 to February 2021. Then they were divided into two groups: patients with or without PVT. NETs procoagulant activity was assessed based on thrombin-antithrombin complex (TAT complex) and Factor X. The levels of plasma markers were determined by ELISA.

RESULTS

There were 28 patients with PVT and 44 patients without PVT. The levels of NETs markers and hypercoagulability markers in the plasma of cirrhosis patients with PVT were significantly higher than those of cirrhosis patients without PVT (p < 0.05). Additionally, the levels of the NETs markers correlated with TAT complex and Factor X (Spearman correlation rho >0.73, p < 0.0001).

CONCLUSIONS

Neutrophil extracellular traps seem to enhance procoagulant activity in LC patients with PVT; thus, they may be a practical predictor of PVT as well as a rapid and easy-to-use diagnostic and treatment guide for PVT in patients with cirrhosis.

Venous Thromboembolism and Critical Limb Events in Patients with Atrial Fibrillation: A Nationwide Population-Based Cohort Study

Little is known about whether venous thromboembolism (VTE) causes worse critical limb events in populations with atrial fibrillation (AF). A retrospective cohort study using claims data from Taiwan's National Health Insurance program between 2001 and 2013 compared AF patients with or without VTE. Outcomes were percutaneous transluminal angioplasty (PTA), amputation, systemic thromboembolism, all-cause mortality, cardiovascular death, ischemic stroke, and acute myocardial infarction. Patients (n = 316,817) with newly diagnosed AF were analyzed; of those, 2514 (0.79%) had VTE history. After inverse probability of treatment weighting, a history of VTE was significantly associated with higher risks of PTA (3.3 vs 2.2%; subdistribution hazard ratio [SHR] 1.47; 95% confidence interval [CI] 1.17-1.84); above knee amputation (0.7 vs 0.3%; HR 2.15; 95% CI 1.10-4.21); systemic thromboembolism (5.8 vs 3.9%; SHR 1.48; 95% CI 1.21-1.80); all-cause mortality (53 vs 46.4%; HR 1.20, 95% CI 1.12-1.29); and cardiovascular death (34.8 vs 29.4%; HR 1.25, 95% CI 1.14-1.36). In conclusion, VTE might increase the risk of critical lower limb events (PTA and above-knee amputation), systemic thromboembolism, and mortality in the AF population. However, current data cannot confirm a causal relationship between VTE and clinical outcomes in this population.

Coagulation and inflammation in cancer: Limitations and prospects for treatment

The development of so-called immune checkpoint inhibitors (ICIs), which target specific molecular processes of tumour growth, has had a transformative effect on cancer treatment. Widespread use of antibody-based medicines to inhibit tumour cell immune evasion by modulating T cell responses is becoming more common. Despite this, response rates are still low, and secondary resistance is an issue that arises often. In addition, a wide range of serious adverse effects is triggered by enhancing the immunological response. As a result of an increased mortality rate, a higher prevalence of thrombotic complications is connected with an increased incidence of immunological reactions, complement activation, and skin toxicity. This suggests that the tumour microenvironment's interaction between coagulation and inflammation is important at every stage of the tumour's life cycle. The coagulation system's function in tumour formation is the topic of this review. By better understanding the molecular mechanisms in which tumour cells circulate, plasmatic coagulation and immune system cells are engaged, new therapy options for cancer sufferers may be discovered.

Platelet-leukocyte crosstalk in COVID-19: How might the reciprocal links between thrombotic events and inflammatory state affect treatment strategies and disease prognosis?

Platelet-leukocyte crosstalk is commonly manifested by reciprocal links between thrombosis and inflammation. Platelet thrombus acts as a reactive matrix that recruits leukocytes to the injury site where their massive accumulation, activation and migration promote thrombotic events while triggering inflammatory responses. As a life-threatening condition with the associations between inflammation and thrombosis, COVID-19 presents diffuse alveolar damage due to exaggerated macrophage activity and cytokine storms. These events, together with direct intracellular virus invasion lead to pulmonary vascular endothelialitis, cell membranes disruption, severe endothelial injury, and thrombosis. The developing pre-alveolar thrombus provides a hyper-reactive milieu that recruits circulating leukocytes to the injury site where their activation contributes to thrombus stabilization and thrombosis propagation, primarily through the formation of Neutrophil extracellular trap (NET). NET fragments can also circulate and deposit in further distance where they may disseminate intravascular thrombosis in severe cases of disease. Thrombi may also facilitate leukocytes migration into alveoli where their accumulation and activation exacerbate cytokine storms and tissue damage, further complicating the disease. Based on these mechanisms, whether an effective anti-inflammatory protocol can prevent thrombotic events, or on the other hand; efficient antiplatelet or anticoagulant regimens may be associated with reduced cytokine storms and tissue damage, is now of interests for several ongoing researches. Thus shedding more light on platelet-leukocyte crosstalk, the review presented here discusses the detailed mechanisms by which platelets may contribute to the pathogenesis of COVID-19, especially in severe cases where their interaction with leukocytes can intensify both inflammatory state and thrombosis in a reciprocal manner.