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

NETosis in myocardial ischemia-reperfusion injury: From mechanisms to therapies (Review)

The present review describes the mechanisms of NETosis and its role in myocardial ischemia-reperfusion injury (MIRI), focusing on the release of neutrophil extracellular traps (NETs) by activated neutrophils. NETs, composed of depolymerized chromatin and granule proteins, are crucial for pathogen entrapment, infection control and immune regulation. However, NET formation, linked to neutrophil death (NETosis), exacerbates MIRI by promoting inflammation and tissue damage. To address therapeutic strategies for NETosis in MIRI, several potential clinically significant approaches were explored, including peptidylarginine deaminase 4 inhibition, DNase therapy, antioxidants, inflammation modulation, and antithrombotic treatments, which not only provide novel diagnostic biomarkers and therapeutic targets in MIRI, but are also expected to improve patient prognosis and advance the development of personalised medicine.

Development of DNase-1 Loaded Polymeric Nanoparticles Synthesized by Inverse Flash Nanoprecipitation for Neutrophil-Mediated Drug Delivery to In Vitro Thrombi

Activated neutrophils release Neutrophil Extracellular Traps (NETs), comprising decondensed chromatin, peroxidases, and serine proteases, which aid in host defense but are also implicated in thrombosis and resistance to thrombolysis. Recombinant DNase 1, which degrades NETs, may aid in thrombus dissolution synergistically with fibrinolytics. However, its short half-life and susceptibility to plasma proteases limit its therapeutic applicability. To address these limitations, DNase1 is encapsulated into polymeric nanoparticles (DNPs) using inverse Flash Nanoprecipitation (iFNP), a scalable nanoparticle synthesis technique. Previously only used with model proteins, the study demonstrates for the first time the feasibility of extending iFNP to the encapsulation of therapeutic proteins. Conditions that promote DNase1 solubility, preserve activity, and demonstrate release resulting in ex vivo NET degradation are detailed. Furthermore, the use of neutrophils, the source of NETs, as carriers for DNPs to enhance targeted delivery is investigated. These findings confirm that DNP-loaded neutrophils maintain key functionalities, including viability and oxidative burst, and associate with in vitro blood clots to deliver nanoparticles, and DNase1 protein. This study not only extends the feasibility of applying iFNP to encapsulate therapeutic proteins into polymeric nanoparticles, a promising alternative to lipid nanoparticles, but also contributes to the emerging literature on neutrophils as delivery vectors for nanocarriers.

Influence of homocysteine on regulating immunothrombosis: mechanisms and therapeutic potential in management of infections

Mechanisms controlling innate immune responses and coagulation are interdependent, evolutionarily entangled and make a complex network to form immuno-thrombosis axis which is an integral part of host-defence response. During infections, immunothrombosis generates intravascular scaffold enabling recognition, trap and destruction of pathogens facilitating tissue integrity. However, the accompanying dysregulation fosters into pathologies associated with thrombosis and regulates severity, morbidity and mortality in infections. Several extrinsic and intrinsic factors such as (epi)genetic mechanisms, age, metabolism and lifestyle regulate immunothrombosis during infections. Mounting evidence demonstrates that homocysteine, a metabolic intermediate of methionine synthesis pathway activate cells participating in immuno-thrombosis such as neutrophils, platelets, monocytes and endothelial cells. Interestingly, multiple infections are significantly associated with perturbed homocysteine metabolism. In the present review, we describe mechanistic insights into how homocysteine drives immuno-thrombotic crosstalk that generate a vicious cycle of inflammation and coagulation that fuels organ failure during infections with an emphasis on sepsis, COVID-19, and other infectious diseases caused by parasites, viral, and bacterial pathogens. Subsequently, we discuss therapeutic strategies targeting homocysteine metabolism that may improve clinical outcomes in infections.

Applications of microfluidic chip technology in microvascular thrombosis research

The formation and progression of microvascular thrombosis are critical mechanisms underlying many vascular-related diseases. Therefore, replicating the microvascular blood flow environment in vitro and investigating the mechanisms of microvascular thrombosis formation are highly significant. In recent years, microfluidic chip technology has been extensively applied in in vitro research for its capability to systematically and comprehensively replicate the complex processes of microvascular thrombosis in laboratory settings. This review systematically examines the development and applications of microfluidic chip technology in microvascular thrombosis research. It begins with a brief summary of the technical features of microfluidic chip technology, followed by a detailed discussion of its applications in constructing in vitro microvascular models, investigating thrombosis mechanisms, and evaluating antithrombotic drug efficacy. Finally, the review summarizes the current research progress and discusses potential directions for future development. This review also systematically explains the breakthrough contribution of microfluidic chips from the perspective of engineering bionics and provides new insights for the pathological research and clinical management of microvascular thrombosis: constructing a high-precision physiological simulation system through bionic topology design and dynamic fluid regulation to achieve high-precision reconstruction of vascular dynamic microenvironment; based on the systems-level dynamics analysis, the dynamic evolution law of multi-factor synergy in the process of thrombosis is revealed; construct a drug-response evaluation system and establish a transformation bridge from micro-mechanism to clinical intervention. In summary, this review is expected to accelerate the development of targeted therapies and diagnostic tools for microvascular thrombosis.

Perfluoroalkyl and polyfluoroalkyl substances interact with platelet glycoprotein Ibα and exacerbate thrombosis

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are highly stable man-made chemicals. They have recently garnered significant attention due to their ubiquitous presence in the environment and deleterious effects on human health including cardiovascular diseases (CVDs). Thrombosis due to platelet activation is a major aspect in CVDs. However, the direct effect and underlying mechanism of PFAS on the platelets remains elusive. Here, we observed that PFAS engagement with the extracellular domain of platelet GPIbα, transduced GPIbα-driven inward signals, resulting in intracellular calcium mobilization, activation of Akt and αⅡbβ3 integrin, culminating in platelet aggregation and procoagulant platelet formation. PFAS pretreatment enhanced GPIb-mediated platelet spreading and thrombus formation under high shear conditions. PFAS-induced platelet activation was markedly decreased in Gpibα-deficient mice. PFAS-primed platelets drove neutrophil extracellular traps formation through GPIbα-dependent pathway. Further, PFAS-exposed mice showed heightened risk of thrombus growth and ischemic stroke. Our findings provide experimental evidence for the causal links between PFAS exposure and thrombotic CVDs. Blockade of GPIbα and the downstream pathways could be an instrumental strategy against PFAS-induced platelet activation and thrombosis.

Beyond a Single Marker: An Update on the Comprehensive Evaluation of Right Ventricular Dysfunction in Pulmonary Thromboembolism

Pulmonary thromboembolism (PE) is a life-threatening condition that often leads to right ventricular (RV) dysfunction, a key determinant of prognosis and clinical management. Biomarkers play a crucial role in the early detection and risk stratification of RV dysfunction in PE, complementing imaging and hemodynamic assessments. Cardiac troponins, B-type natriuretic peptides, and novel biomarkers, such as heart-type fatty acid-binding protein (H-FABP) and growth differentiation factor-15 (GDF-15), provide valuable insights into myocardial injury, overload, and stress. This article explores the clinical possible significance of these biomarkers, their predictive value, and their potential to guide therapeutic strategies in patients with PE. Understanding the role of biomarkers in RV dysfunction assessment may improve patient outcomes focusing on early intervention and personalized treatment approaches.

Extracellular Traps in Inflammation: Pathways and Therapeutic Targets

New roles for immune cells, overcoming the classical cytotoxic response, have been highlighted by growing evidence. The immune cells, such as neutrophils, monocytes/macrophages, and eosinophils, are versatile cells involved in the release of web-like DNA structures called extracellular traps (ETs) which represent a relevant mechanism by which these cells prevent microbes' dissemination. In this process, many enzymes, such as elastase, myeloperoxidase (MPO), and microbicidal nuclear and granule proteins, which contribute to the clearance of entrapped microorganisms after DNA binding, are involved. However, an overproduction and release of ETs can cause unwanted and dangerous effects in the host, resulting in several pathological manifestations, among which are chronic inflammatory disorders, autoimmune diseases, cancer, and diabetes. In this review, we discuss the release mechanisms and the double-edged sword role of ETs both in physiological and in pathological contexts. In addition, we evaluated some possible strategies to target ETs aimed at either preventing their formation or degrading existing ones.

Impact of peptidylarginine deiminase 4 (PAD4) deficiency in a fecal-induced peritonitis model of sepsis

BACKGROUND

Peptidylarginine deiminase 4 (PAD4) citrullinates histones, enabling the release of neutrophil extracellular traps. While neutrophil extracellular traps capture and kill pathogens, they also drive immunothrombosis, potentially worsening sepsis outcomes. However, it remains unclear whether PAD4 deficiency is beneficial or harmful in sepsis.

OBJECTIVES

To evaluate the impact of PAD4 deficiency in a fecal-induced peritonitis sepsis model, with and without antibiotic treatment, and incorporating fluid resuscitation in both sexes.

METHODS

Wild-type and PAD4 knockout (PAD4-/-) C57Bl/6 mice received intraperitoneal injections of fecal slurry (0.6 mg/g). Mice received buprenorphine every 8 hours and antibiotics/fluids every 12 hours. Survival studies were also conducted without antibiotics at a reduced fecal dose (0.4 mg/g). Mice were culled at 8 hours or 48 hours after infection. Organs, blood, and peritoneal cavity fluid were collected. Plasma levels of interleukin (IL)-6, IL-10, cell-free DNA, and thrombin-antithrombin were quantified, as well as bacterial loads in blood and peritoneal cavity fluid. Organ histology/immunohistochemistry was performed.

RESULTS

Female PAD4-/- mice had worsened survival compared with female wild-type mice. Male mice exhibited worse survival than females in both strains. Antibiotics eliminated survival differences between strains and sexes. Septic PAD4-/- mice had reduced IL-10 in the early phase of sepsis, increased lung myeloperoxidase, and exacerbated lung injury compared with septic wild-type mice.

CONCLUSION

PAD4 deficiency in female mice worsened survival in the fecal-induced peritonitis sepsis model. In both strains, male mice exhibited worse survival compared with their female counterparts. PAD4 deficiency is associated with reduced IL-10, increased neutrophil infiltration, and exacerbated lung injury. Antibiotics eliminated survival differences between strains and sexes.

Plasma H3Cit-DNA Discriminates Between Cancer and Inflammation in a Cohort of Patients with Unspecific Cancer Symptoms

Cancer detection is challenging, especially in patients with unspecific cancer symptoms. Biomarkers could identify patients at high risk of cancer. Prior studies indicate that neutrophil extracellular traps (NETs) are associated with cancer, but also with autoimmune and infectious diseases. The objective of this prospective study was to investigate markers associated with NET formation (nucleosomal citrullinated histone 3 [H3Cit-DNA], cell free DNA [cfDNA] and neutrophil elastase [NE]), and c-reactive protein (CRP) in patients with unspecific cancer symptoms, such as fatigue, weight loss or radiological sign of malignancy without an apparent primary tumor, referred to the Diagnostic Center at Danderyd Hospital in Sweden. Blood samples were drawn on admission, before cancer diagnosis. Out of 475 patients, 160 (34%) were diagnosed with cancer, 56 (12%) with autoimmune disease, 32 (7%) with infectious disease, 71 (15%) with other diseases and 156 (33%) received no diagnosis. H3Cit-DNA, cfDNA, NE and CRP were significantly higher in patients with cancer compared to patients without cancer (p < 0.0001, p < 0.0001, p = 0.004, and p = 0.0002 respectively). H3Cit-DNA, but not cfDNA, NE or CRP, was significantly elevated in patients with cancer compared to patients with autoimmune disease (p = 0.0001). H3Cit-DNA, cfDNA, NE or CRP did not differ between cancer and infectious disease. In conclusion, H3Cit-DNA is elevated in patients diagnosed with cancer compared to non-cancer patients with the same symptomatology. Further studies should evaluate if H3Cit-DNA could aid in selecting patients that would benefit the most from a rapid cancer diagnostic work-up.

Modic changes: From potential molecular mechanisms to future research directions (Review)

Low back pain (LBP) is a leading cause of disability worldwide. Although not all patients with Modic changes (MCs) experience LBP, MC is often closely associated with LBP and disc degeneration. In clinical practice, the focus is usually on symptoms related to MC, which are hypothesized to be associated with LBP; however, the link between MC and nerve compression remains unclear. In cases of intervertebral disc herniation, nerve compression is often the definitive cause of symptoms. Recent advances have shed light on the pathophysiology of MC, partially elucidating its underlying mechanisms. The pathogenesis of MC involves complex bone marrow‑disc interactions, resulting in bone marrow inflammation and edema. Over time, hematopoietic cells are gradually replaced by adipocytes, ultimately resulting in localized bone marrow sclerosis. This process creates a barrier between the intervertebral disc and the bone marrow, thereby enhancing the stability of the vertebral body. The latest understanding of the pathophysiology of MC suggests that chronic inflammation plays a significant role in its development and hypothesizes that the complement system may contribute to its pathological progression. However, this hypothesis requires further research to be confirmed. The present review we proposed a pathological model based on current research, encompassing the transition from Modic type 1 changes (MC1) to Modic type 2 changes (MC2). It discussed key cellular functions and their alterations in the pathogenesis of MC and outlined potential future research directions to further elucidate its mechanisms. Additionally, it reviewed the current clinical staging and pathogenesis of MC, recommended the development of an updated staging system and explored the prospects of integrating emerging artificial intelligence technologies.

Neutrophil Extracellular Traps: At the Interface of Thrombosis and Comorbidities

Since their discovery in 2004, neutrophil extracellular traps (NETs) have been at the center of multidisciplinary attention. Although a key tool in neutrophil-mediated immunity, these filamentous, enzyme-enriched DNA-histone complexes can be detrimental to tissues and have been identified as an underlying factor in a range of pathological conditions. Building on more than 20 years of research into NETs, this review places thrombosis, the pathological formation of blood clots, in the spotlight. From this point of view, we discuss the structure and formation of NETs, as well as the interaction of their components with the hemostatic system, dissecting the pathways through which NETs exert their marked effect on formation and the dissolution of thrombi. We pay distinct attention to the latest developments in the research of a key player in NET formation, peptidyl-arginine-deiminase (PAD) enzymes: their types, sources, and potential cross-play with the hemostatic machinery. Besides these molecular details, we elaborate on the link between pathological thrombosis, NETs, and widespread conditions that represent a debilitating public health burden worldwide, such as sepsis and neoplasms. Finally, future implications on the treatment of thrombosis-related conditions will be discussed.

The Role of Neutrophil Extracellular Traps in Atherosclerosis: From the Molecular to the Clinical Level

Atherosclerosis is a chronic inflammatory condition that is typified by the deposition of lipids and the subsequent inflammation of medium and large arteries. Neutrophil extracellular traps (NETs) are fibrous meshworks of DNA, histones, and granzymes expelled by activated neutrophils in response to a variety of pathogenic conditions. In addition to their role in pathogen eradication, NETs have been demonstrated to play a pivotal role in the development of atherosclerosis. This article presents a review of the bidirectional interactions in which atherosclerosis-related risk factors stimulate the formation of NETs, which in turn support disease progression. This article emphasizes the involvement of NETs in the various stages of atherogenesis and development, influencing multiple factors such as the vascular endothelium, platelets, the inflammatory milieu, and lipid metabolism. The findings of this study offer new insights and avenues for further investigation into the processes underlying the formation and regulation of the vascular inflammatory microenvironment in atherosclerosis. Finally, potential targeted therapeutic strategies for NETs are discussed to facilitate their progression to clinical practice (Graphical Abstract).

Neutrophil extracellular traps: potential thrombotic markers and therapeutic targets in colorectal cancer

Neutrophil extracellular traps (NETs) are promising promoters in venous thromboembolism (VTE). In the present study, we have investigated the potential thrombogenic role of NETs in colorectal cancer (CRC). A total of 583 patients with gastrointestinal malignancies who were diagnosed with or without VTE by extremities arteriovenous ultrasound and computed tomography were enrolled. The incidence of VTE in CRC was as high as 17.53%. In serological ELISA experiments, Cit-H3, myeloperoxidase, and cfDNA were significantly overexpressed in CRC patients with VTE compared with CRC patients without VTE and healthy individuals. Neutrophils from CRC patients with VTE produced appreciable amounts of NETs after stimulation with phorbol-12-myristate-13-acetate, which were lacking in CRC patients without VTE and healthy individuals. CfDNA was positively correlated with plasmin-α2-antiplasmin complex and tissue plasmin activator inhibitor-1 complex, and Cit-H3 was positively correlated with plasmin-α2-antiplasmin complex, suggesting that NETs are associated with increased fibrinolytic activity. We screened some NETs-related genes by analyzing several high-throughput sequencing datasets of VTE and NETs. FCGR1A was identified as the optimal target gene by pan-cancer expression analysis and survival analysis. FCGR1A was significantly overexpressed in the peripheral blood of CRC patients without VTE compared with healthy individuals and showed a positive correlation with cfDNA. Neutrophil-derived NETs were significantly reduced by FCGR1A inhibitor exposure. These findings indicate that NETs are actively involved in VTE in CRC. NETs are promising thrombotic marker and therapeutic target in CRC to prevent the thrombotic consequences of cancer.

Severely Ill COVID-19 Patients May Exhibit Hypercoagulability Despite Escalated Anticoagulation

Introduction: Severely ill COVID-19 patients receiving prophylactic-dose anticoagulation exhibit high rates of thrombosis and mortality. The escalation of anticoagulation also does not reduce mortality and has an uncertain impact on thrombosis rates. The reasons why escalated doses fail to outperform prophylactic doses in reducing risks of thrombosis and death in severely ill COVID-19 patients remain unclear. We hypothesized that escalated anticoagulation would not effectively prevent hypercoagulability and, consequently, would not reduce the risk of thrombosis and death in some severely ill patients. Methods: We conducted a prospective multicenter study that enrolled 3860 COVID-19 patients, including 1654 severely ill. They received different doses of low-molecular-weight or unfractionated heparin, and their blood coagulation was monitored with activated partial thromboplastin time, D-dimer, and Thrombodynamics. A primary outcome was hypercoagulability detected by Thrombodynamics. Blood samples were collected at the trough level of anticoagulation. Results: We found that escalated anticoagulation did not prevent hypercoagulability in 28.3% of severely ill patients at the trough level of the pharmacological activity. Severely ill patients with such hypercoagulability had higher levels of inflammation markers and better creatinine clearance compared to severely ill patients without it. Hypercoagulability detected by Thrombodynamics was associated with a 1.68-fold higher hazard rate for death and a 3.19-fold higher hazard rate for thrombosis. Elevated D-dimer levels were also associated with higher hazard rates for thrombosis and death, while shortened APTTs were not. The simultaneous use of Thrombodynamics and D-dimer data enhanced the accuracy for predicting thrombotic events and fatal outcomes in severely ill patients. Conclusions: Thrombodynamics reliably detects hypercoagulability in COVID-19 patients and can be used in conjunction with D-dimer to assess the risk of thrombosis and death in severely ill patients. The pharmacological effect of LMWH at the trough level might be too low to prevent thrombosis in some severely ill patients with severe inflammation and better creatinine clearance, even if escalated doses are used.

Exosomes in Precision Oncology and Beyond: From Bench to Bedside in Diagnostics and Therapeutics

Exosomes have emerged as pivotal players in precision oncology, offering innovative solutions to longstanding challenges such as metastasis, therapeutic resistance, and immune evasion. These nanoscale extracellular vesicles facilitate intercellular communication by transferring bioactive molecules that mirror the biological state of their parent cells, positioning them as transformative tools for cancer diagnostics and therapeutics. Recent advancements in exosome engineering, artificial intelligence (AI)-driven analytics, and isolation technologies are breaking barriers in scalability, reproducibility, and clinical application. Bioengineered exosomes are being leveraged for CRISPR-Cas9 delivery, while AI models are enhancing biomarker discovery and liquid biopsy accuracy. Despite these advancements, key obstacles such as heterogeneity in exosome populations and the lack of standardized isolation protocols persist. This review synthesizes pioneering research on exosome biology, molecular engineering, and clinical translation, emphasizing their dual roles as both mediators of tumor progression and tools for intervention. It also explores emerging areas, including microbiome-exosome interactions and the integration of machine learning in exosome-based precision medicine. By bridging innovation with translational strategies, this work charts a forward-looking path for integrating exosomes into next-generation cancer care, setting it apart as a comprehensive guide to overcoming clinical and technological hurdles in this rapidly evolving field.

Reactive oxygen species: Orchestrating the delicate dance of platelet life and death

Platelets, which are vital for blood clotting and immunity, need to maintain a delicately balanced relationship between generation and destruction. Recent studies have highlighted that reactive oxygen species (ROS), which act as second messengers in crucial signaling pathways, are crucial players in this dance. This review explores the intricate connection between ROS and platelets, highlighting their dual nature. Moderate ROS levels act as potent activators, promoting megakaryocyte (MK) differentiation, platelet production, and function. They enhance platelet binding to collagen, increase coagulation, and directly trigger cascades for thrombus formation. However, this intricate role harbors a double-edged sword. Excessive ROS unleash its destructive potential, triggering apoptosis and reducing the lifespan of platelets. High levels can damage stem cells and disrupt vital redox-dependent signaling, whereas uncontrolled activation promotes inappropriate clotting, leading to thrombosis. Maintaining a precise balance of ROS within the hematopoietic microenvironment is paramount for optimal platelet homeostasis. While significant progress has been made, unanswered questions remain concerning specific ROS signaling pathways and their impact on platelet disorders. Addressing these questions holds the key to unlocking the full potential of ROS-based therapies for treating platelet-related diseases such as thrombocytopenia and thrombosis. This review aims to contribute to this ongoing dialog and inspire further exploration of this exciting field, paving the way for novel therapeutic strategies that harness the benefits of ROS while mitigating their dangers.

Statins as an Adjunctive Antithrombotic Agent in Thrombotic Antiphospholipid Syndrome: Mechanisms and Clinical Implications

The thrombotic physiopathology of antiphospholipid syndrome (APS) is complex, heterogeneous, and dynamic. While venous thromboembolism (VTE) is the most common initial presentation, arterial thrombotic events (ATE) become more frequent in advanced stages and are associated with high morbidity and mortality. Despite the use of oral anticoagulants (OACs), thrombotic APS remains associated with a high risk of recurrent thrombosis. Given their potential antithrombotic effects capable of reducing the risk of both VTE and ATE, statins have been proposed as an adjunctive therapy to OACs for patients with APS and recurrent thrombosis. However, this recommendation is primarily based on studies not specifically conducted in APS populations, with only preclinical data or evidence from retrospective observational studies available from APS patients cohorts. For these reasons, this narrative review aims to synthesise the studies evaluating the potential antithrombotic effects of statins in patients with APS, highlighting the progress made and identifying areas for future research.

Deficiency of neutrophil gelatinase-associated lipocalin elicits a hemophilia-like bleeding and clotting disorder in mice

ABSTRACT

Coagulation is related to inflammation, but the key pathway, especially innate immune system and coagulation regulation, is not well understood and need to be further explored. Here, we demonstrated that neutrophil gelatinase-associated lipocalin (NGAL), an innate immune inflammatory mediator, is upregulated in patients with thrombosis. Furthermore, it contributes to the initiation and amplification of coagulation, hemostasis, and thrombosis. This occurs by enhancing tissue factor expression on the cell surface, potentiating various clotting factors such as thrombin, kallikrein, factor XIa (FXIa), and FVIIa, promoting thrombin-induced platelet aggregation, and inhibiting antithrombin. NGAL knockout led to strikingly prolonged clot reaction time and kinetic time in thromboelastography analysis, along with reduced thrombus generation angle and lower thrombus maximum amplitude, which were in line with remarkably prolonged activated partial thromboplastin time and prothrombin time. In several mouse hemostasis and thrombosis models, NGAL overexpression or IV administration promoted coagulation and hemostasis and aggravated thrombosis, whereas NGAL knockout or treatment with anti-NGAL monoclonal antibody significantly prolonged bleeding time and alleviated thrombus formation. Notably, NGAL knockout prolonged mouse tail bleeding time or artery occlusion time to over 40 or 60 minutes, respectively, resembling uncontrollable bleeding and clotting disorder seen in hemophilic mice. Furthermore, anti-NGAL monoclonal antibody treatment markedly reduced the formation of blood clots in inflammation-induced thrombosis models. Collectively, these findings unveil a previously unidentified role of NGAL in the processes of coagulation, hemostasis, and thrombosis, as well as the cross talk between innate immunity, inflammation, and coagulation. Thus, modulating NGAL levels could potentially help balance thrombotic and hemorrhagic risks.

The Interplay Between Immunity, Inflammation and Endothelial Dysfunction

The endothelium is pivotal in multiple physiological processes, such as maintaining vascular homeostasis, metabolism, platelet function, and oxidative stress. Emerging evidence in the past decade highlighted the immunomodulatory function of endothelium, serving as a link between innate, adaptive immunity and inflammation. This review examines the regulation of the immune-inflammatory axis by the endothelium, discusses physiological immune functions, and explores pathophysiological processes leading to endothelial dysfunction in various metabolic disturbances, including hyperglycemia, obesity, hypertension, and dyslipidaemia. The final section focuses on the novel, repurposed, and emerging therapeutic targets that address the immune-inflammatory axis in endothelial dysfunction.

Histologic evidence of neutrophil extracellular traps and fibrin(ogen) deposition in liver biopsies from patients with inflammatory liver disease

Background

Liver disease is often characterized by the activation of coagulation and inflammation. Experimental studies suggest that the interaction between neutrophils and platelets with local activation of coagulation could contribute to liver injury progression, but there have been limited studies in humans.

Objectives

We studied the hemostatic components and neutrophil extracellular traps (NETs) in liver biopsies from patients with different inflammatory liver diseases.

Methods

Liver biopsies from patients with inflammatory liver disease (alcoholic steatohepatitis [ASH], autoimmune hepatitis, primary sclerosing cholangitis, metabolic-associated steatohepatitis, and allograft ischemia-reperfusion injury (IRI), each n = 20) were stained for fibrin(ogen), platelets, and NETs. The correlation of NET formation with deposition of hemostatic components and laboratory measures of disease severity was investigated.

Results

In 75% of the liver biopsies, no fibrin(ogen) was detectable, and only 20% of the biopsies showed minimal deposition. Overall, 50% of liver biopsies stained positive for NETs. Platelet deposition and NET formation were highest in IRI, where it correlated with histologic severity of injury (r = .61 [95% CI, .22-.84]; P < .01) and ASH. Platelet deposition was associated with NET formation (r = .44 [95% CI, .27-.59]; P < .001) and colocalized in the biopsies. NET formation, but not fibrin and platelet deposition, was moderately associated with the model of end-stage liver disease score (r = .29 [95% CI, .07-.49]; P < .01).

Conclusion

In contrast to experimental studies, we demonstrated minimal intrahepatic fibrin(ogen) deposition in different types of human inflammatory liver disease. Histologic evidence for intrahepatic NETs was common and most pronounced in acute ASH and IRI and was associated with platelet deposition and disease severity.

Ex vivo observation of Pythium insidiosum-antigen treated neutrophils on three Pythium insidiosum strains isolated from vascular pythiosis patients

The mechanisms of Pythium insidiosum-antigen (PIA) immunotherapy activating a patient's immune system are unknown. We evaluated the interleukin-8 (IL-8) serum levels during P. insidiosum infection and after vaccination with PIA in vascular pythiosis cases. Furthermore, we studied the anti-P. insidiosum activity of neutrophils stimulated with various concentrations of PIA ex vivo in 3 strains of P. insidiosum isolated from vascular pythiosis patients. IL-8 serum levels were evaluated using the ELISA technique. We assessed the effect of PIA-stimulated neutrophils on the viability of zoospores using MTT assay, visualized neutrophil extracellular trap (NET) formation via microscopy, and measured the levels of double-stranded DNA (dsDNA) using PicoGreen dsDNA quantitation assay in 3 strains of P. insidiosum isolated from vascular pythiosis patients. Serum levels of IL-8 gradually lowered from the early to the end phases of vaccination with PIA among the surviving group of vascular pythiosis cases. Neutrophils stimulated with 0.01 µg/ml PIA reduced zoospore viability significantly compared to PIA-unstimulated neutrophils for strain 1 and strain 3 (p < .05). Neutrophils stimulated with 0.01, 0.1, 1, and 10 µg/ml PIA exhibited significantly lower zoospore viability than PIA-unstimulated neutrophils for strain 2 (p < .05). IL-8 can be used as a biomarker for monitoring vascular pythiosis cases treated with the PIA vaccine. Also, anti-P. insidiosum activity of PIA-stimulated neutrophils was probably due to the disruption of cellular activity in zoospores rather than the mechanisms based on the formation of NETs.

Neutrophil extracellular traps - an a-list-actor in a variety of diseases

Neutrophil extracellular traps (NETs) represent a response mechanism in which activated neutrophils release DNA-based webs, adorned with histones and neutrophil proteases, to capture and eliminate invasive microorganisms. However, when these neutrophils become excessively activated, much more proteases associated with NETs are liberated into surrounding tissues or bloodstreams, thereby altering the cellular milieu and causing tissue damage. Recent research has revealed that NETs may play significant roles in the emergence and progression of various diseases, spanning from infections, inflammation to autoimmune disorders and cancers. In this review, we delve deeply into the intricate and complex mechanisms that underlie the formation of NETs and their profound interplay with various clinical pathologies. We aim to describe the application perspectives of NETs related proteins in specific disease diagnosis and treatment.

Relationship Between the Systemic Immune-Inflammation Index and Deep Venous Thrombosis After Spinal Cord Injury: A Cross-Sectional Study

Purpose

To explore the relationship between the systemic immune-inflammation index (SII) and deep venous thrombosis (DVT) in patients with spinal cord injury (SCI).

Methods

This cross-sectional study included data from 382 participants with SCI. The SII was calculated for all participants. Logistic regression, smooth curve fitting, interaction effects were used to substantiate the research objectives.

Results

The overall prevalence of DVT was 23.1% (22.4% among males, 25.6% among females). A positive association between SII and the risk for DVT was observed (odds ratio 1.39 [95% CI 1.03-1.87]; P=0.032), independent of confounders. Similar patterns of association were observed in the subgroup analysis (P values for interaction, all >0.05). Further sensitivity analyses provided confidence that the results were reliable and unlikely to be substantially altered by unmeasured confounding factors.

Conclusion

Results of the present suggest that higher SII may be associated with DVT in patients with SCI, highlighting a potential link between SII and DVT. These findings underscore the potential of SII as a valuable predictive biomarker for DVT, thus offering a promising avenue for early detection and intervention strategies in patients with SCI.

Elevated Platelet Aggregation in Patients with Ovarian Cancer: More than Just Increased Platelet Count

Background: Patients with ovarian cancer have high platelet counts, which correlate with disease burden, incidence, and lethality of blood clots (thrombosis). We hypothesized that elevated aggregation is associated with both increased platelet number and altered behavior of platelets in patients with ovarian cancer. Methods: Healthy controls and patients with suspected or diagnosed ovarian cancer were evaluated for complete blood counts. To evaluate the effects of platelet count versus platelet behavior, equal platelet-rich plasma (PRP) volumes versus equal platelet numbers were used in platelet aggregation assays. Arachidonic acid, adenosine diphosphate, and collagen platelet agonists were used to induce aggregation. Volunteers were grouped into healthy controls (23), benign/borderline cases (7), and cancer cases (25 ovarian, 1 colorectal, and 2 endometrial). Results: The rate and amount of platelet aggregation were higher in patients compared to healthy controls regardless of whether the same platelet number or PRP volume was used. Compared to healthy controls, patients with untreated ovarian cancer exhibited high levels of platelet activation markers, P-selectin (27.06 vs. 31.06 ng/mL, p = 0.03), and beta-thromboglobulin (3.073 vs. 4.091 µg/mL, p = 0.02) in their plasma. The significance of the elevation and its correlations with platelet number or PRP volume varied depending on the agonist. Platelet (305.88 vs. 134.12, p < 0.0001) and white blood cell (8.459 vs. 5.395, p < 0.01) counts (×109/L) were elevated pre-chemotherapy and decreased post-chemotherapy, respectively. Conclusions: Elevated platelet aggregation is caused by both altered platelet number and behavior in patients with ovarian cancer. These results support the study of antiplatelet agents for thrombosis prevention in these patients.

Didang decoction attenuates cancer-associated thrombosis by inhibiting PAD4-dependent NET formation in lung cancer

This research aims to investigate the impact of Didang decoction (DD) on the formation of neutrophil extracellular traps (NETs) and cancer-associated thrombosis in lung cancer. BALB/c nude mice were used to establish xenograft models for inducing deep vein thrombosis. Tumor growth and thrombus length were assessed. The impact of DD on NET generation was analyzed using enzyme-linked immunosorbent assay, immunofluorescence staining, quantitative real-time PCR, and western blot analysis, both in vivo and in vitro. CI-amidine, a PAD4 inhibitor, was employed to evaluate the role of PAD4 in the generation of NETs. In vivo studies demonstrated that treatment with DD reduced tumor growth, inhibited thrombus formation, and decreased the levels of NET markers in the serum, tumor tissues, neutrophils, and thrombus tissues of mice. Additional data indicated that DD could suppress neutrophil counts, the release of tissue factor (TF), and the activation of thrombin-activated platelets, all of which contributed to increased formation of NETs in mouse models. In vitro, following incubation with conditioned medium (CM) derived from Lewis lung carcinoma cells, the expression of NET markers in neutrophils was significantly elevated, and an extracellular fibrous network structure was observed. Nevertheless, these NET-associated changes were partially counteracted by DD. Additionally, CI-amidine reduced the expression of NET markers in CM-treated neutrophils, consistent with the effects of DD. Collectively, DD inhibits cancer-associated thrombosis in lung cancer by decreasing PAD4-dependent NET formation through the regulation of TF-mediated thrombin-platelet activation. This presents a promising therapeutic strategy for preventing and treating venous thromboembolism in lung cancer.

Targeting neutrophils extracellular traps, a promising anti-thrombotic therapy for natural products from traditional Chinese herbal medicine

Thrombi are the main cause of vascular occlusion and contribute significantly to cardiovascular events and death. Neutrophils extracellular traps (NETs)-induced thrombosis plays a vital role in thrombotic complications and it takes the main responsibility for the resistance of fibrinolysis. However, the conventional anti-thrombotic therapies are inadequate to treat NETs-induced thrombotic complications but carry a high risk of bleeding. Consequently, increased attention has shifted towards exploring novel anti-thrombotic treatments targeting NETs. Interestingly, accumulating evidences prove that natural products from traditional Chinese herbal medicines have a great potential to mitigate thrombosis through inhibiting generous NETs formation and degrading excessive NETs. In this review, we elaborated the formation and degradation of NETs and highlighted its pivotal role in immunothrombosis through interactions with platelets and coagulation factors. Since available anti-thrombotic drugs targeting NETs are deficient, we further summarized the natural products and compounds from traditional Chinese herbal medicines which exert effective actions on regulating NETs formation and also have anti-thrombotic effects. Our findings underscore the diverse effects of natural products in targeting NETs, including relieving inflammation and oxidative stress of neutrophils, inhibiting neutrophils activation and DNA efflux, suppressing granule proteins release, reducing histones and promoting DNA degradation. This review aims to highlight the significance of natural medicines in anti-thrombotic therapies through targeting NETs and to lay a groundwork for developing novel anti-thrombotic agents from traditional Chinese herbal medicines.

The pivotal role of neutrophil extracellular traps in cardiovascular diseases: Mechanisms and therapeutic implications

Cardiovascular diseases (CVDs) continue to pose a significant burden on global health, prominently contributing to morbidity and mortality rates worldwide. Recent years have witnessed an increasing recognition of the intricate involvement of neutrophil extracellular traps (NETs) in the pathology of diverse cardiovascular conditions. This review provides a comprehensive analysis of the multifaceted functions of NETs in cardiovascular diseases, shedding light on the impact on atherosclerosis, myocardial infarction, heart failure, myocarditis, atrial fibrillation, aortic stenosis, and the potential therapeutic avenues targeting NETs.

Association of corticosteroid therapy with reduced acute kidney injury and lower NET markers in severe COVID-19: an observational study

BACKGROUND

Acute kidney injury (AKI) is common in critical cases of coronavirus disease 2019 (COVID-19) and associated with worse outcome. Dysregulated neutrophil extracellular trap (NET) formation is one of several suggested pathophysiological mechanisms involved in the development of COVID-19 associated AKI. The corticosteroid dexamethasone was implemented as a standard treatment for severe COVID-19 as of June 2020. A sub-analysis of a prospective observational single center study was performed to evaluate the effect of corticosteroid treatment on AKI development and NET markers in critical cases of COVID-19.

RESULTS

Two hundred and ten adult patients admitted to intensive care at a tertiary level hospital due to respiratory failure or shock secondary to SARS-CoV-2-infection between March 13th 2020 and January 14th 2021 were included in the study. Ninety-seven of those did not receive corticosteroids. One hundred and thirteen patients were treated with corticosteroids [dexamethasone (n = 98) or equivalent treatment (n = 15)], but the incidence of AKI was assessed only in patients that received corticosteroids before any registered renal dysfunction (n = 63). Corticosteroids were associated with a lower incidence of AKI (19% vs 55.8%, p < 0.001). Fewer patients demonstrated detectable concentrations of extracellular histones in plasma when treated with corticosteroids (8.7% vs 43.1%; p < 0.001). Extracellular histones and in particular non-proteolyzed histones were observed more frequently with increasing AKI severity (p < 0.001). MPO-DNA was found in lower concentrations in patients that received corticosteroids before established renal dysfunction (p = 0.03) and was found in higher concentrations in patients with AKI stage 3 (p = 0.03). Corticosteroids did not ameliorate established AKI during the first week of treatment.

CONCLUSION

Corticosteroid treatment in severe COVID-19 is associated with a lower incidence of AKI and reduced concentrations of NET markers in plasma.

Piezo1 expression in neutrophils regulates shear-induced NETosis

Neutrophil infiltration and subsequent extracellular trap formation (NETosis) is a contributing factor in sterile inflammation. Furthermore, neutrophil extracellular traps (NETs) are prothrombotic, as they provide a scaffold for platelets and red blood cells to attach to. In circulation, neutrophils are constantly exposed to hemodynamic forces such as shear stress, which in turn regulates many of their biological functions such as crawling and NETosis. However, the mechanisms that mediate mechanotransduction in neutrophils are not fully understood. In this study, we demonstrate that shear stress induces NETosis, dependent on the shear stress level, and increases the sensitivity of neutrophils to NETosis-inducing agents such as adenosine triphosphate and lipopolysaccharides. Furthermore, shear stress increases intracellular calcium levels in neutrophils and this process is mediated by the mechanosensitive ion channel Piezo1. Activation of Piezo1 in response to shear stress mediates calpain activity and cytoskeleton remodeling, which consequently induces NETosis. Thus, activation of Piezo1 in response to shear stress leads to a stepwise sequence of cellular events that mediates NETosis and thereby places neutrophils at the centre of localized inflammation and prothrombotic effects.

Deletion of pyruvate dehydrogenase kinases reduces susceptibility to deep vein thrombosis in mice

ABSTRACT

Neutrophils contribute to deep vein thrombosis (DVT) by releasing prothrombotic neutrophil extracellular traps (NETs). NET formation (known as NETosis) is an energy-intensive process that requires an increased rate of aerobic glycolysis. The metabolic enzymes pyruvate dehydrogenase kinases (PDKs) inhibit the pyruvate dehydrogenase complex to divert the pyruvate flux from oxidative phosphorylation toward aerobic glycolysis. Herein, we identified that the combined deletion of PDK2 and PDK4 (PDK2/4-/-) renders mice less susceptible to DVT (measured by thrombus incidence, weight, and length) in the inferior vena cava-stenosis model at day 2 after surgery. Compared with wild-type (WT) mice, the venous thrombus obtained from PDK2/4-/- mice exhibited reduced citrullinated histone content, a known marker of NETs. In line with in vivo observations, phorbol 12-myristate 13-acetate (PMA)-stimulated PDK2/4-/- neutrophils displayed reduced NETosis and secretion of cathepsin G and elastase compared with PMA-stimulated WT neutrophils. The formation of platelet aggregates mediated by PMA-stimulated PDK2/4-/- neutrophils were significantly reduced compared with PMA-stimulated WT neutrophils. Finally, PDK2/4-/- neutrophils exhibited reduced levels of intracellular Ca2+ concentration, extracellular signal-regulated kinase 1/2 (Erk1/2) phosphorylation, and glycolytic proton efflux rate (a measure of aerobic glycolysis), known to facilitate NETosis. Together, these findings elucidate, to our knowledge, for the first time, the fundamental role of PDK2/4 in regulating NETosis and acute DVT.

Extracellular RNA Induces Neutrophil Recruitment Via Toll-Like Receptor 3 During Venous Thrombosis After Vascular Injury

BACKGROUND

Venous thromboembolism is associated with endothelial cell activation that contributes to the inflammation-dependent activation of the coagulation system. Cellular damage is associated with the release of different species of extracellular RNA (eRNA) involved in inflammation and coagulation. TLR3 (toll-like receptor 3), which recognizes (viral) single-stranded or double-stranded RNAs and self-RNA fragments, might be the receptor of these species of eRNA during venous thromboembolism. Here, we investigate how the TLR3/eRNA axis contributes to venous thromboembolism.

METHODS AND RESULTS

Thrombus formation and size in wild-type and TLR3 deficient (-/-) mice were monitored by ultrasonography after venous thrombosis induction using the ferric chloride and stasis models. Mice were treated with RNase I, with polyinosinic-polycytidylic acid, a TLR3 agonist, or with RNA extracted from murine endothelial cells. Gene expression and signaling pathway activation were analyzed in HEK293T cells overexpressing TLR3 in response to eRNA or in human umbilical vein endothelial cells transfected with a small interference RNA against TLR3. Plasma clot formation on treated human umbilical vein endothelial cells was analyzed. Thrombosis exacerbated eRNA release in vivo and increased eRNA content within the thrombus. RNase I treatment reduced thrombus size compared with vehicle-treated mice (P<0.05). Polyinosinic-polycytidylic acid and eRNA treatments increased thrombus size in wild-type mice (P<0.01 and P<0.05), but not in TLR3-/- mice, by reinforcing neutrophil recruitment (P<0.05). Mechanistically, TLR3 activation in endothelial cells promotes CXCL5 (C-X-C motif chemokine 5) secretion (P<0.001) and NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation (P<0.05). Finally, eRNA triggered plasma clot formation in vitro (P<0.01).

CONCLUSIONS

We show that eRNA and TLR3 activation enhance venous thromboembolism through neutrophil recruitment possibly through secretion of CXCL5, a potent neutrophil chemoattractant.

Development of a Clonal and High-Yield Mammalian Cell Line for the Manufacturing of a Hyperactive Human DNase I with Extended Plasma Half-Life Using PASylation® Technology

Cumulative evidence from several pre-clinical studies suggests that restoration of plasma DNase activity in a thrombo-inflammatory state may improve clinical outcomes. Following injury, hyperactivated immune cells release large amounts of granular proteins together with DNA, which often accumulate in the surrounding environment in so-called neutrophil extracellular traps (NETs). Degradation of excess NETs by systemic DNase administration offers a promising therapeutic approach to ameliorate inflammation and dissolve intravascular clots. In order to expand the therapeutic utility of human DNase I, a variant of the enzyme was developed that has both a prolonged systemic half-life and a higher catalytic activity compared to Dornase alfa (Pulmozyme®), the recombinant form of DNase I approved for inhaled therapy of cystic fibrosis. The hyperactive enzyme was "PASylated" by genetic fusion with a strongly hydrophilic and biodegradable PAS-polypeptide to increase its hydrodynamic volume and retard kidney filtration. A stable TurboCell™ CHO-K1-based cell line was generated which is suitable for the future production of PASylated DNase I according to good manufacturing practice (GMP). Furthermore, a robust bioprocess strategy was devised and an effective downstream process was developed. The final protein product is characterized by excellent purity, favorable physicochemical properties, a 14-fold higher DNA-degrading activity than Dornase alfa and a sustained pharmacokinetic profile, with a 22-fold slower clearance in rats.

The crosstalk between immune cells and tumor pyroptosis: advancing cancer immunotherapy strategies

Pyroptosis is a cell death process characterized by cell swelling until membrane rupture and release of intracellular contents. As an effective tumor treatment strategy, inducing tumor cell pyroptosis has received widespread attention. In this process, the immune components within the tumor microenvironment play a key regulatory role. By regulating and altering the functions of immune cells such as cytotoxic T lymphocytes, natural killer cells, tumor-associated macrophages, and neutrophils, tumor cell pyroptosis can be induced. This article provides a comprehensive review of the molecular mechanisms of cell pyroptosis, the impact of the tumor immune microenvironment on tumor cell pyroptosis, and its mechanisms. It aims to gain an in-depth understanding of the communication between the tumor immune microenvironment and tumor cells, and to provide theoretical support for the development of new tumor immunotherapies.

Ischaemic Stroke, Thromboembolism and Clot Structure

Ischaemic stroke is a major cause of morbidity and mortality worldwide. Blood clotting and thromboembolism play a central role in the pathogenesis of ischaemic stroke. An increasing number of recent studies indicate changes in blood clot structure and composition in patients with ischaemic stroke. In this review, we aim to summarise and discuss clot structure, function and composition in ischaemic stroke, including its relationships with clinical diagnosis and treatment options such as thrombolysis and thrombectomy. Studies are summarised in which clot structure and composition is analysed both in vitro from patients' plasma samples and ex vivo in thrombi obtained through interventional catheter-mediated thrombectomy. Mechanisms that drive clot composition and architecture such as neutrophil extracellular traps and clot contraction are also discussed. We find that, while in vitro clot structure in plasma samples from ischaemic stroke patients are consistently altered, showing denser clots that are more resistant to fibrinolysis, current data on the composition and architecture of ex vivo clots obtained by thrombectomy are more variable. With the potential of advances in technologies underpinning both the imaging and retrieving of clots, we expect that future studies in this area will generate new data that is of interest for the diagnosis, optimal treatment strategies and clinical management of patients with ischaemic stroke.

Therapeutic Avenues to Modulate B-Cell Function in Patients With Cardiovascular Disease

The adaptive immune system plays an important role in the development and progression of atherosclerotic cardiovascular disease. B cells can have both proatherogenic and atheroprotective roles, making treatments aimed at modulating B cells important therapeutic targets. The innate-like B-cell response is generally considered atheroprotective, while the adaptive response is associated with mixed consequences for atherosclerosis. Additionally, interactions of B cells with components of the adaptive and innate immune system, including T cells and complement, also represent key points for therapeutic regulation. In this review, we discuss therapeutic approaches based on B-cell depletion, modulation of B-cell survival, manipulation of both the antibody-dependent and antibody-independent B-cell response, and emerging immunization techniques.

Mesenchymal stem cell-derived extracellular vesicles accelerate diabetic wound healing by inhibiting NET-induced ferroptosis of endothelial cells

Impaired angiogenesis is a major factor contributing to delayed wound healing in diabetes. Dysfunctional mitochondria promote the formation of neutrophil extracellular traps (NETs), obstructing angiogenesis during wound healing. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have shown promise in promoting tissue repair and regeneration in diabetes; however, the precise pathways involved in this process remain unclear. In this study, NET-induced ferroptosis of endothelial cells (ECs) and angiogenesis were assessed in diabetic wound samples from both patients and animal models. In vitro and in vivo experiments were performed to examine the regulatory mechanisms of NETs in ECs using specific inhibitors and gene-knockout mice. MSC-EVs encapsulating dysfunctional mitochondria were used to trigger mitochondrial fusion and restore mitochondrial function in neutrophils to suppress NET formation. Angiogenesis in wound tissue was evaluated using color laser Doppler imaging and vascular density analysis. Wound healing was evaluated via macroscopic analysis and histological evaluation of the epithelial gap. NET-induced ferroptosis of ECs was validated as a crucial factor contributing to the impairment of angiogenesis in diabetic wounds. Mechanistically, NETs regulated ferroptosis by suppressing the PI3K/AKT pathway. Furthermore, MSC-EVs transferred functional mitochondria to neutrophils in wound tissue, triggered mitochondrial fusion, and restored mitochondrial function, thereby reducing NET formation. These results suggest that inhibiting NET formation and EC ferroptosis or activating the PI3K/AKT pathway can remarkably improve wound healing. In conclusion, this study reveals a novel NET-mediated pathway involved in wound healing in diabetes and suggests an effective therapeutic strategy for accelerating wound healing.

Arterial Thrombosis in Patients with Cancer

Patients with cancer are at increased risk of arterial thromboembolic disease due to the presence of risk factors common to both the development of cancer and arterial thrombosis, the cancer itself, and the treatments provided to treat cancer. We review here the epidemiology and pathophysiology of arterial thromboembolic disease in cancer, along with its prevention and treatment strategies. We also propose a generalized approach for the management of arterial thromboembolic disease in this patient population.

Immunological role of Gas6/TAM signaling in hemostasis and thrombosis

The immune system is an emerging regulator of hemostasis and thrombosis. The concept of immunothrombosis redefines the relationship between coagulation and immunomodulation, and the Gas6/Tyro3-Axl-MerTK (TAM) signaling pathway builds the bridge across them. During coagulation, Gas6/TAM signaling pathway not only activates platelets, but also promotes thrombosis through endothelial cells and vascular smooth muscle cells involved in inflammatory responses. Thrombosis appears to be a common result of a Gas6/TAM signaling pathway-mediated immune dysregulation. TAM TK and its ligands have been found to be involved in coagulation through the PI3K/AKT or JAK/STAT pathway in various systemic diseases, providing new perspectives in the understanding of immunothrombosis. Gas6/TAM signaling pathway serves as a breakthrough target for novel therapeutic strategies to improve disease management. Many preclinical and clinical studies of TAM receptor inhibitors are in process, confirming the pivotal role of Gas6/TAM signaling pathway in immunothrombosis. Therapeutics targeting the TAM receptor show potential both in anticoagulation management and immunotherapy. Here, we review the immunological functions of the Gas6/TAM signaling pathway in coagulation and its multiple mechanisms in diseases identified to date, and discuss the new clinical strategies that may generated by these roles.

Neutrophil extracellular traps (NETs) and fibrotic diseases

Fibrosis, a common cause and serious outcome of organ failure that can affect any organ, is responsible for up to 45% of all deaths in various clinical settings. Both preclinical models and clinical trials investigating various organ systems have shown that fibrosis is a highly dynamic process. Although many studies have sought to gain understanding of the mechanism of fibrosis progression, their findings have been mixed. In recent years, increasing evidence indicates that neutrophil extracellular traps (NETs) are involved in many inflammatory and autoimmune disorders and participate in the regulation of fibrotic processes in various organs and systems. In this review, we summarize the current understanding of the role of NETs in fibrosis development and progression and their possibility as therapeutic targets.

NET-targeted nanoparticles for antithrombotic therapy in pregnancy

Pulmonary embolism caused by deep vein thrombosis (DVT) is a major contributor to maternal morbidity and mortality. There is still an unmet need for safe and effective treatment options for DVT during pregnancy. Recent research has shown that neutrophil extracellular trap (NET) formation plays a very vital role in thrombosis. We created nanoparticles surface-modified by neutrophil elastase (NE)-binding peptide that can target activated neutrophils specifically in vitro and in vivo. Prussian blue nanoparticles (PB NPs) designed in the core scavenges abnormally elevated reactive oxygen species (ROS) in the vascular microenvironment and acts as a photothermal agent to mediate photothermal therapy (PTT) to damage fibrin network structure. Based on the data we have included, this noninvasive therapeutic approach is considered safe for both mothers and the fetus. Furthermore, our findings indicate that this therapeutic approach has a significant alleviation effect on intrauterine growth restriction caused by maternal thrombosis.

Neutrophil Virucidal Activity Against SARS-CoV-2 Is Mediated by Neutrophil Extracellular Traps

BACKGROUND

Inflammation in the lungs and other vital organs in COVID-19 is characterized by the presence of neutrophils and a high concentration of neutrophil extracellular traps (NETs), which seems to mediate host tissue damage. However, it is not known whether NETs could have virucidal activity against SARS-CoV-2.

METHODS

We investigated whether NETs could prevent SARS-CoV-2 replication in neutrophils and epithelial cells and what the consequence of NETs degradation would be in K18-humanized ACE2 transgenic mice infected with SARS-CoV-2.

RESULTS

Here, by immunofluorescence microscopy, we observed that viral particles colocalize with NETs in neutrophils isolated from patients with COVID-19 or healthy individuals and infected in vitro. The inhibition of NETs production increased virus replication in neutrophils. In parallel, we observed that NETs inhibited virus abilities to infect and replicate in epithelial cells after 24 hours of infection. Degradation of NETs with DNase I prevented their virucidal effect in vitro. Using K18-humanized ACE2 transgenic mice, we observed a higher viral load in animals treated with DNase I. However, the virucidal effect of NETs was not dependent on neutrophil elastase or myeloperoxidase activity.

CONCLUSIONS

Our results provide evidence of the role of NETosis as a mechanism of SARS-CoV-2 viral capture and inhibition.

Histone content, and thus DNA content, is associated with differential in vitro lysis of acute ischemic stroke clots

BACKGROUND

Fibrin, von Willebrand factor, and extracellular DNA from neutrophil extracellular traps all contribute to acute ischemic stroke thrombus integrity.

OBJECTIVES

In this study, we explored how the proteomic composition of retrieved thromboemboli relates to susceptibility to lysis with distinct thrombolytics.

METHODS

Twenty-six retrieved stroke thromboemboli were portioned into 4 segments, with each subjected to 1 hour of in vitro lysis at 37 °C in 1 of 4 solutions: tissue plasminogen activator (tPA), tPA + von Willebrand factor-cleaving ADAMTS-13, tPA + DNA-cleaving deoxyribonuclease (DNase) I, and all 3 enzymes. Lysis, characterized by the percent change in prelysis and postlysis weight, was compared across the solutions and related to the corresponding abundance of proteins identified on mass spectrometry for each of the thromboemboli used in lysis.

RESULTS

Solutions containing DNase resulted in approximately 3-fold greater thrombolysis than that with the standard-of-care tPA solution (post hoc Tukey, P < .01 for all). DNA content was directly related to lysis in solutions containing DNase (Spearman's ρ > 0.39 and P < .05 for all significant histones) and inversely related to lysis in solutions without DNase (Spearman's ρ < -0.40 and P < .05 for all significant histones). Functional analysis suggests distinct pathways associated with susceptibility to thrombolysis with tPA (platelet-mediated) or DNase (innate immune system-mediated).

CONCLUSION

This study demonstrates synergy of DNase and tPA in thrombolysis of stroke emboli and points to DNase as a potential adjunct to our currently limited selection of thrombolytics in treating acute ischemic stroke.

microRNAs and thrombo-inflammation: relationship in sight

PURPOSE OF REVIEW

Thrombo-inflammation is a multifaceted pathologic process involving various cells such as platelets, neutrophils, and monocytes. In recent years, microRNAs have been consistently implicated as regulators of these cells.

RECENT FINDINGS

MicroRNAs play a regulatory role in several platelet receptors that have recently been identified as contributing to thrombo-inflammation and neutrophil extracellular trap (NET) formation. In addition, a growing body of evidence has shown that several intracellular and extracellular microRNAs directly promote NET formation.

SUMMARY

Targeting microRNAs is a promising therapeutic approach to control thrombosis in patients with both infectious and noninfectious inflammatory diseases. Future research efforts should focus on elucidating the specific roles of microRNAs in thrombo-inflammation and translating these findings into tangible benefits for patients.

Neutrophil Extracellular Traps in Breast Cancer: Roles in Metastasis and Beyond

Despite advances in the treatment of breast cancer, the disease continues to exhibit high global morbidity and mortality. The importance of neutrophils in cancer development has been increasingly recognized. Neutrophil extracellular traps (NETs) are web-like structures released into the extracellular space by activated neutrophils, serving as a potential antimicrobial mechanism for capturing and eliminating microorganisms. The roles played by NETs in cancer development have been a subject of intense research in the last decade. In breast cancer, current evidence suggests that NETs are involved in various stages of cancer development, particularly during metastasis. In this review, we try to provide an updated overview of the roles played by NETs in breast cancer metastasis. These include: 1) facilitating systemic dissemination of cancer cells; 2) promoting cancer-associated inflammation; 3) facilitating cancer-associated thrombosis; 4) facilitating pre-metastatic niche formation; and 5) awakening dormant cancer cells. The translational implications of NETs in breast cancer treatment are also discussed. Understanding the relationship between NETs and breast cancer metastasis is expected to provide important insights for developing new therapeutic strategies for breast cancer patients.

Neutrophil Extracellular Traps in Cardiovascular and Aortic Disease: A Narrative Review on Molecular Mechanisms and Therapeutic Targeting

Neutrophil extracellular traps (NETs), composed of DNA, histones, and antimicrobial proteins, are released by neutrophils in response to pathogens but are also recognized for their involvement in a range of pathological processes, including autoimmune diseases, cancer, and cardiovascular diseases. This review explores the intricate roles of NETs in different cardiovascular conditions such as thrombosis, atherosclerosis, myocardial infarction, COVID-19, and particularly in the pathogenesis of abdominal aortic aneurysms. We elucidate the mechanisms underlying NET formation and function, provide a foundational understanding of their biological significance, and highlight the contribution of NETs to inflammation, thrombosis, and tissue remodeling in vascular disease. Therapeutic strategies for preventing NET release are compared with approaches targeting components of formed NETs in cardiovascular disease. Current limitations and potential avenues for clinical translation of anti-NET treatments are discussed.

Association of the neutrophil-to-lymphocyte ratio with the occurrence of venous thromboembolism and arterial thrombosis

OBJECTIVE

This study aimed to assess the association of the neutrophil-to-lymphocyte ratio (NLR) with the occurrence of venous thromboembolism (VTE) and arterial thrombosis (AT).

METHODS

This was a retrospective cross-sectional study including 585 medical records obtained from all consecutive patients who were suspected of having thrombosis.

RESULTS

The AT group had a higher neutrophil count and NLR and a lower lymphocyte count than the non-thrombosis group. Receiver operating characteristic curve analysis showed the ability of the NLR to predict the presence of AT. The cut-off value for the NLR was 4.44. No distinction was found in the NLR between the VTE and non-thrombosis groups. Regression analysis showed that a high NLR was an independent factor related to the presence of AT. Patients with an NLR ≥ 4.44 had a higher risk of AT than those with an NLR < 4.44 (odds ratio = 2.015, 95% confidence interval: 1.180-3.443).

CONCLUSION

A high NLR may be considered a predictive factor for the occurrence of AT, but an association with the presence of VTE was not found.

Neutrophil extracellular traps promote gastric cancer cell metastasis via the NAT10-mediated N4-acetylcytidine modification of SMYD2

It has been reported that the formation of neutrophil extracellular traps (NETs) is associated with cancer metastasis. The current study aimed to explore the effects of NETs on gastric cancer (GC) cell metastasis and uncover their underlying mechanism. NETs were measured in the plasma of patients with GC. Then, GC cells were treated with NETs to assess cell viability, migration, and invasion using cell counting kit 8 and Transwell assay, The liver metastasis and xenograft tumor mouse models were established to assess tumor growth and metastasis. The N4-acetylcytidine (ac4C) modification of SET and MYND domain containing 2 (SMYD2) mediated by NAT10 was evaluated using acetylated RNA immunoprecipitation. The results showed that the level of NETs was increased in the plasma of patients with GC, particularly in those with metastatic GC. In addition, GC cell co-treatment with NETs promoted cell viability, migration and invasion, while NAT10 or SMYD2 knockdown abrogated this effect. NAT10 also promoted the ac4C modification of SMYD2, thus increasing SMYD2 stability. Furthermore, NETs promoted the metastasis of GC cells in the liver in vivo. Overall, the results of the present study demonstrated that NETs promoted GC cell metastasis via the NAT10-mediated ac4C modification of SMYD2. These findings suggested that inhibiting the formation of NETs could be an effective approach for attenuating GC progression.

Tumor metabolic crosstalk and immunotherapy

Tumor cells must resist the host's immune system while maintaining growth under harsh conditions of acidity and hypoxia, which indicates that tumors are more robust than normal tissue. Immunotherapeutic agents have little effect on solid tumors, mostly because of the tumor density and the difficulty of penetrating deeply into the tissue to achieve the theoretical therapeutic effect. Various therapeutic strategies targeting the tumor microenvironment (TME) have been developed. Immunometabolic disorders play a dominant role in treatment resistance at both the TME and host levels. Understanding immunometabolic factors and their treatment potential may be a way forward for tumor immunotherapy. Here, we summarize the metabolism of substances that affect tumor progression, the crosstalk between the TME and immunosuppression, and some potential tumor-site targets. We also summarize the progress and challenges of tumor immunotherapy.

Impaired balance between neutrophil extracellular trap formation and degradation by DNases in COVID-19 disease

BACKGROUND

Thrombo-inflammation and neutrophil extracellular traps (NETs) are exacerbated in severe cases of COVID-19, potentially contributing to disease exacerbation. However, the mechanisms underpinning this dysregulation remain elusive. We hypothesised that lower DNase activity may be associated with higher NETosis and clinical worsening in patients with COVID-19.

METHODS

Biological samples were obtained from hospitalized patients (15 severe, 37 critical at sampling) and 93 non-severe ambulatory cases. Our aims were to compare NET biomarkers, functional DNase levels, and explore mechanisms driving any imbalance concerning disease severity.

RESULTS

Functional DNase levels were diminished in the most severe patients, paralleling an imbalance between NET markers and DNase activity. DNase1 antigen levels were higher in ambulatory cases but lower in severe patients. DNase1L3 antigen levels remained consistent across subgroups, not rising alongside NET markers. DNASE1 polymorphisms correlated with reduced DNase1 antigen levels. Moreover, a quantitative deficiency in plasmacytoid dendritic cells (pDCs), which primarily express DNase1L3, was observed in critical patients. Analysis of public single-cell RNAseq data revealed reduced DNase1L3 expression in pDCs from severe COVID-19 patient.

CONCLUSION

Severe and critical COVID-19 cases exhibited an imbalance between NET and DNase functional activity and quantity. Early identification of NETosis imbalance could guide targeted therapies against thrombo-inflammation in COVID-19-related sepsis, such as DNase administration, to avert clinical deterioration.

TRIAL REGISTRATION

COVERAGE trial (NCT04356495) and COLCOV19-BX study (NCT04332016).