Circulating Nucleosomes and Neutrophil Activation as Risk Factors for Deep Vein Thrombosis

Neutrophil Extracellular Traps (NETs) Are Associated with Type 2 Diabetes and Diabetic Foot Ulcer Related Amputation: A Prospective Cohort Study

INTRODUCTION

The prevalence of diabetes mellitus and its sequelae has been on the rise, and diabetic foot ulcer (DFU) is the leading cause of non-traumatic lower limb amputation globally. The rising occurrence and financial burden associated with DFU necessitate improved clinical assessment and treatment. Diabetes has been found to enhance the formation of neutrophil extracellular traps (NETs) by neutrophils, and excessive NETs have been implicated in tissue damage and impaired wound healing. However, there is as yet insufficient evidence to clarify the value of NETs in assessing and predicting outcomes of DFU.

METHODS

We designed this prospective study with three cohorts formed from type 2 diabetes mellitus (T2DM) patients with DFU (n = 200), newly diagnosed T2DM patients (n = 42), and healthy donors (n = 38). Serum levels of NETs were detected for all groups, and the prognostic value for DFU-related amputation was analyzed.

RESULTS

The results showed that serum NET levels of the DFU group were significantly higher than in the T2DM group (P < 0.05), which also had significantly elevated serum NET levels compared to healthy donors (P < 0.05). Multivariate Cox regression showed that serum NET levels, diabetic foot surgical history, and Wagner grade were the risk factors for amputation (P < 0.05), and these three variables also exhibited the highest coefficient values in additional Lasso Cox regression. For patients with DFU, Kaplan-Meier curves showed that high serum NET levels associated with higher amputation probability (HR = 0.19, P < 0.01) and ROC curve based on NET value showed good validity for amputation (AUC: 0.727, CI 0.651-0.803).

CONCLUSION

Elevated serum NET levels serve as an easily accessible serological prognostic marker for assessing the risk of DFU-related amputation, thereby offering evaluation metrics for healthcare providers. Further investigations are necessary to understand the mechanisms driving this relationship.

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.

Involvement of regulated cell deaths in aging and age-related pathologies

Aging is a pathophysiological process that causes a gradual and permanent reduction in all biological system functions. The phenomenon is caused by the accumulation of endogenous and exogenous damage as a result of several stressors, resulting in significantly increased risks of various age-related diseases such as neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. In addition, aging appears to be connected with mis-regulation of programmed cell death (PCD), which is required for regular cell turnover in many tissues sustained by cell division. According to the recent nomenclature, PCDs are physiological forms of regulated cell death (RCD) useful for normal tissue development and turnover. To some extent, some cell types are connected with a decrease in RCD throughout aging, whereas others are related with an increase in RCD. Perhaps the widespread decline in RCD markers with age is due to a slowdown of the normal rate of homeostatic cell turnover in various adult tissues. As a result, proper RCD regulation requires a careful balance of many pro-RCD and anti-RCD components, which may render cell death signaling pathways more sensitive to maladaptive signals during aging. Current research, on the other hand, tries to further dive into the pathophysiology of aging in order to develop therapies that improve health and longevity. In this scenario, RCD handling might be a helpful strategy for human health since it could reduce the occurrence and development of age-related disorders, promoting healthy aging and lifespan. In this review we propose a general overview of the most recent RCD mechanisms and their connection with the pathophysiology of aging in order to promote targeted therapeutic strategies.

Malignancy-associated ischemic stroke: Implications for diagnostic and therapeutic workup

BACKGROUND

Patients with malignancies have an increased risk of suffering ischemic stroke via several mechanisms such as coagulation dysfunction and other malignancy-related effects as well as iatrogenic causes. Moreover, stroke can be the first sign of an occult malignancy, termed as malignancy-associated ischemic stroke (MAS). Therefore, timely diagnostic assessment and targeted management of this complex clinical situation are critical.

FINDINGS

Patients with both stroke and malignancy have atypical ages, risk factors, and often exhibit malignancy-related symptoms and multiple lesions on neuroimaging. New biomarkers such as eicosapentaenoic acid and blood mRNA profiles may help in distinguishing MAS from other strokes. In terms of treatment, malignancy should not be considered a contraindication, given comparable rates of recanalization and complications between stroke patients with or without malignancies.

CONCLUSION

In this review, we summarize the latest developments in diagnosing and managing MAS, especially stroke with occult malignancies, and provide new recommendations from recently emerged clinical evidence for diagnostic and therapeutic workup strategies.

The Diagnostic Utility of Natural Killer Cell Subsets in Deep Vein Thrombosis

Background

Natural killer (NK) cells are important components of adaptive and innate immune responses. NK cell subsets have different functions and may play a role in vascular disorders. This study aimed to evaluate the proportions of NK cells and their subsets to determine whether they can be used as markers of venous thrombosis and to identify whether there was a link between NK cell proportion and citrullinated histone (H3) levels.

Patients and Methods

This study included 100 participants divided into Group I (n=50, patients with deep venous thrombosis (DVT)) and Group II (n=50, age- and sex-matched healthy controls). Group I was further categorized into Group Ia (n=25, patients with acute DVT) and Group Ib (n=25, patients with chronic DVT). The proportions of NK cells and their subsets were evaluated by flow cytometry using CD3/CD16/CD56. The levels of citrullinated histones (H3) were estimated using enzyme-linked immunosorbent assay (ELISA).

Results

Compared to the control group, DVT patients had a significantly lower proportion of (CD56 dim/CD16+) NK cells, a significantly higher proportion of (CD56-/CD16+) NK cells and a high level of citrullinated histone (H3).

Conclusion

NK cell subsets and citrullinated histone (H3) could be used as markers for DVT and as targets for therapeutic drugs to inhibit the formation or progression of thrombosis.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Immune Thrombosis: Exploring the Significance of Immune Complexes and NETosis

Neutrophil extracellular traps (NETs) are major contributors to inflammation and autoimmunity, playing a key role in the development of thrombotic disorders. NETs, composed of DNA, histones, and numerous other proteins serve as scaffolds for thrombus formation and promote platelet activation, coagulation, and endothelial dysfunction. Accumulating evidence indicates that NETs mediate thrombosis in autoimmune diseases, viral and bacterial infections, cancer, and cardiovascular disease. This article reviews the role and mechanisms of immune complexes in NETs formation and their contribution to the generation of a prothrombotic state. Immune complexes are formed by interactions between antigens and antibodies and can induce NETosis by the direct activation of neutrophils via Fc receptors, via platelet activation, and through endothelial inflammation. We discuss the mechanisms by which NETs induced by immune complexes contribute to immune thrombotic processes and consider the potential development of therapeutic strategies. Targeting immune complexes and NETosis hold promise for mitigating thrombotic events and reducing the burden of immune thrombosis.

C1-inhibitor treatment in patients with severe complement-mediated autoimmune hemolytic anemia

Complement-mediated (CM) autoimmune hemolytic anemia (AIHA) is characterized by the destruction of red blood cells (RBCs) by autoantibodies that activate the classical complement pathway. These antibodies also reduce transfusion efficacy via the lysis of donor RBCs. Because C1-inhibitor (C1-INH) is an endogenous regulator of the classical complement pathway, we hypothesized that peritransfusional C1-INH in patients with severe CM-AIHA reduces complement activation and hemolysis, and thus enhances RBC transfusion efficacy. We conducted a prospective, single-center, phase 2, open-label trial (EudraCT2012-003710-13). Patients with confirmed CM-AIHA and indication for the transfusion of 2 RBC units were eligible for inclusion. Four IV C1-INH doses (6000, 3000, 2000, and 1000 U) were administered with 12-hour intervals around RBC transfusion. Serial blood samples were analyzed for hemolytic activity, RBC opsonization, complement activation, and inflammation markers. Ten patients were included in the study. C1-INH administration increased plasma C1-INH antigen and activity, peaking at 48 hours after the first dose and accompanied by a significant reduction of RBC C3d deposition. Hemoglobin levels increased briefly after transfusion but returned to baseline within 48 hours. Overall, markers of hemolysis, inflammation, and complement activation remained unchanged. Five grade 3 and 1 grade 4 adverse event occurred but were considered unrelated to the study medication. In conclusion, peritransfusional C1-INH temporarily reduced complement activation. However, C1-INH failed to halt hemolytic activity in severe transfusion-dependent-CM-AIHA. We cannot exclude that posttransfusional hemolytic activity would have been even higher without C1-INH. The potential of complement inhibition on transfusion efficacy in severe CM-AIHA remains to be determined.

Cell-free histones and the cell-based model of coagulation

The cell-based model of coagulation remains the basis of our current understanding of clinical hemostasis and thrombosis. Its advancement on the coagulation cascade model has enabled new prohemostatic and anticoagulant treatments to be developed. In the past decade, there has been increasing evidence of the procoagulant properties of extracellular, cell-free histones (CFHs). Although high levels of circulating CFHs released following extensive cell death in acute critical illnesses, such as sepsis and trauma, have been associated with adverse coagulation outcomes, including disseminated intravascular coagulation, new information has also emerged on how its local effects contribute to physiological clot formation. CFHs initiate coagulation by tissue factor exposure, either by destruction of the endovascular barrier or induction of endoluminal tissue factor expression on endothelia and monocytes. CFHs can also bind prothrombin directly, generating thrombin via the alternative prothrombinase pathway. In amplifying and augmenting the procoagulant signal, CFHs activate and aggregate platelets, increase procoagulant material bioavailability through platelet degranulation and Weibel-Palade body exocytosis, activate intrinsic coagulation via platelet polyphosphate release, and induce phosphatidylserine exposure. CFHs also inhibit protein C activation and downregulate thrombomodulin expression to reduce anti-inflammatory and anticoagulant effects. In consolidating clot formation, CFHs augment the fibrin polymer to confer fibrinolytic resistance and integrate neutrophil extracellular traps into the clot structure. Such new information holds the promise of new therapeutic developments, including improved targeting of immunothrombotic pathologies in acute critical illnesses.

The effect of neutrophil extracellular traps in venous thrombosis

Neutrophil extracellular traps (NETs) as special release products of neutrophils have received extensive attention. They are composed of decondensed chromatin and coated with nucleoproteins, including histones and some granulosa proteins. NETs can form a network structure to effectively capture and eliminate pathogens and prevent their spread. Not only that, recent studies have shown that NETs also play an important role in venous thrombosis. This review provides the most important updated evidence regarding the mechanism of NETs formation and the role of NETs in the process of venous thrombosis. The potential prophylactic and therapeutic value of NETs in venous thrombotic disease will also be discussed.

NETs-Induced Thrombosis Impacts on Cardiovascular and Chronic Kidney Disease

Arterial and venous thrombosis constitute a major source of morbidity and mortality worldwide. Association between thrombotic complications and cardiovascular and other chronic inflammatory diseases are well described. Inflammation and subsequent initiation of thrombotic events, termed immunothrombosis, also receive growing attention but are still incompletely understood. Nevertheless, the clinical relevance of aberrant immunothrombosis, referred to as thromboinflammation, is evident by an increased risk of thrombosis and cardiovascular events in patients with inflammatory or infectious diseases. Proinflammatory mediators released from platelets, complement activation, and the formation of NETs (neutrophil extracellular traps) initiate and foster immunothrombosis. In this review, we highlight and discuss prominent and emerging interrelationships and functions between NETs and other mediators in immunothrombosis in cardiovascular disease. Also, with patients with chronic kidney disease suffering from increased cardiovascular and thrombotic risk, we summarize current knowledge on neutrophil phenotype, function, and NET formation in chronic kidney disease. In addition, we elaborate on therapeutic targeting of NETs-induced immunothrombosis. A better understanding of the functional relevance of antithrombotic mediators which do not increase bleeding risk may provide opportunities for successful therapeutic interventions to reduce thrombotic risk beyond current treatment options.

Multiallelic Copy Number Variation in ORM1 is Associated with Plasma Cell-Free DNA Levels as an Intermediate Phenotype for Venous Thromboembolism

Venous thromboembolism (VTE) is a common disease with high heritability. However, only a small portion of the genetic variance of VTE can be explained by known genetic risk factors. Neutrophil extracellular traps (NETs) have been associated with prothrombotic activity. Therefore, the genetic basis of NETs could reveal novel risk factors for VTE. A recent genome-wide association study of plasma cell-free DNA (cfDNA) levels in the Genetic Analysis of Idiopathic Thrombophilia 2 (GAIT-2) Project showed a significant associated locus near ORM1. We aimed to further explore this candidate region by next-generation sequencing, copy number variation (CNV) quantification, and expression analysis using an extreme phenotype sampling design involving 80 individuals from the GAIT-2 Project. The RETROVE study with 400 VTE cases and 400 controls was used to replicate the results. A total of 105 genetic variants and a multiallelic CNV (mCNV) spanning ORM1 were identified in GAIT-2. Of these, 17 independent common variants, a region of 22 rare variants, and the mCNV were significantly associated with cfDNA levels. In addition, eight of these common variants and the mCNV influenced ORM1 expression. The association of the mCNV and cfDNA levels was replicated in RETROVE (p-value = 1.19 × 10-6). Additional associations between the mCNV and thrombin generation parameters were identified. Our results reveal that increased mCNV dosages in ORM1 decreased gene expression and upregulated cfDNA levels. Therefore, the mCNV in ORM1 appears to be a novel marker for cfDNA levels, which could contribute to VTE risk.

Neutrophil levels upon admission for the assessment of acute pulmonary embolism with intermediate- and high-risk: an indicator of thrombosis and inflammation

BACKGROUND

Risk prediction rules are important to establish appropriate treatment and management strategy for patients with different risk classification of pulmonary embolism (PE). Neutrophils are considered to be related to PE as an essential marker of inflammation. However, few studies have reported the association between neutrophil levels and risk classification of acute PE (APE). The aim of this study was to investigate the role of neutrophil levels upon admission in the assessment of risk classification of APE.

METHODS

A total of 299 consecutive APE patients and 90 patients without APE confirmed by computed tomographic pulmonary angiography were retrospectively screened. APE patients were stratified into two subgroups according to clinical guidelines: low- (n = 233) and intermediate- and high-risk (n = 60) APE.

RESULTS

The neutrophil levels in intermediate- and high-risk APE patients were significantly higher compared to low-risk APE or non-APE patients (P < 0.001). In multivariable logistic regression analysis, neutrophil levels were significantly and independently associated with intermediate- and high-risk APE (odds ratio = 1.239, 95% confidence interval [CI] 1.055-1.455, P = 0.009). Neutrophil levels were positively correlated with the pulmonary embolism severity index score (r = 0.357, P < 0.001), high sensitive C-reactive protein, D-dimer and pulmonary artery obstruction index (PAOI), in the overall population of APE patients. Receiver-operating characteristic curve analysis revealed that neutrophils had a better diagnostic value for intermediate- and high-risk APE (area under the curve [AUC] = 0.760, 95% CI 0.695-0.826; P < 0.001) compared to PAOI (AUC = 0.719) and D-dimer (AUC = 0.645).

CONCLUSIONS

High neutrophil levels upon admission were significantly and independently associated with intermediate- and high-risk APE, which could be regarded as an indicator of inflammation and thrombosis in APE simultaneously. The potent diagnostic role of neutrophil levels and their competitive advantage over PAOI and D-dimer for the assessment of APE risk classification are suggested.

Biomarkers of Neutrophil Activation in Patients with Symptomatic Chronic Peripheral Artery Disease Predict Worse Cardiovascular Outcome

Neutrophils play a role in cardiovascular (CV) disease. However, relatively scant evidence exists in the setting of peripheral artery disease (PAD). The aims of this study were to measure biomarkers of neutrophil activation in patients with symptomatic chronic PAD compared with healthy controls, to assess their association with PAD severity, and to evaluate their prognostic value in patients with PAD. The following circulating markers of neutrophil degranulation were tested: polymorphonuclear neutrophil (PMN) elastase, neutrophil gelatinase-associated lipocalin (NGAL), and myeloperoxidase (MPO). Neutrophil extracellular traps (NETs) were quantified by measuring circulating MPO–DNA complexes. Patients with PAD underwent a comprehensive series of vascular tests. The occurrence of 6-month major adverse CV (MACE) and limb events (MALE) was assessed. Overall, 110 participants were included, 66 of which had PAD. After adjustment for conventional CV risk factors, PMN-elastase (adjusted odds ratio [OR]: 1.008; 95% confidence interval [CI]: 1.002–1.015; p = 0.006), NGAL (adjusted OR: 1.045; 95%CI: 1.024–1.066; p < 0.001), and MPO (adjusted OR: 1.013; 95%CI: 1.001–1.024; p = 0.028) were significantly associated with PAD presence. PMN-elastase (adjusted hazard ratio [HR]: 1.010; 95%CI: 1.000–1.020; p = 0.040) and MPO (adjusted HR: 1.027; 95%CI: 1.004–1.051; p = 0.019) were predictive of 6-month MACE and/or MALE. MPO displayed fair prognostic performance on receiver operating characteristic (ROC) curve analyses, with an area under the curve (AUC) of 0.74 (95%CI: 0.56–0.91) and a sensitivity and specificity of 0.80 and 0.65, respectively, for a cut-off of 108.37 ng/mL. MPO–DNA showed a weak inverse correlation with transcutaneous oximetry (TcPO2) on proximal foot (adjusted ρ −0.287; p = 0.032). In conclusion, in patients with symptomatic chronic PAD, enhanced neutrophil activity may be associated with an increased risk of acute CV events, rather than correlate with disease severity. Further research is needed to clarify the role of neutrophils in PAD natural history.

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.

Evaluation of the relationship between monocyte to high-density lipoprotein cholesterol ratio and thrombus burden in patients with deep vein thrombosis

OBJECTIVE

The purpose of this study was to evaluate monocyte count and high-density lipoprotein cholesterol levels and their ratio (monocyte/high-density lipoprotein ratio) in patients with deep venous thrombosis as well as to determine whether this ratio at the time of diagnosis can be an indicator of thrombus burden in terms of thrombus location in deep venous thrombosis.

METHODS

We retrospectively analyzed the patient's diagnosis of deep venous thrombosis confirmed with venous Doppler ultrasound, using a database query for outpatients between 2018 and 2022. Of 378 patients included, blood count results at the time of diagnosis were available for 356. We recruited 300 age- and sex-matched patients with appropriate blood counts, without a diagnosis of deep venous thrombosis, as the control group, by querying the outpatient clinic database. The monocyte/high-density lipoprotein ratio was computed from the ratio of monocyte count to high-density lipoprotein-C. Patients were categorized based on the level of thrombus and the number of vein segments involved as evidenced by Doppler ultrasound findings.

RESULTS

The serum level of monocyte/high-density lipoprotein ratio was significantly higher in the patient group compared to the control group (p<0.01). Patients with proximal deep venous thrombosis had a higher mean monocyte/high-density lipoprotein ratio (19.6±5.1 vs. 17.1±5.5; p<0.01) than patients with distal deep venous thrombosis. Monocyte/high-density lipoprotein ratio increased with the number of vein segments involved (p<0.01).

CONCLUSION

Monocyte/high-density lipoprotein ratio is significantly elevated in patients with deep venous thrombosis when compared to the control group. Monocyte/high-density lipoprotein ratio levels were correlated with disease burden reflected by thrombus location and the number of vein segments involved in deep venous thrombosis patients.

Targeting thromboinflammation in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disease, where persistent presence of antiphospholipid antibodies (aPL) leads to thrombotic and obstetric complications. APS is a paradigmatic thromboinflammatory disease. Thromboinflammation is a pathophysiological mechanism coupling inflammation and thrombosis, which contributes to the pathophysiology of cardiovascular disease. APS can serve as a model to unravel mechanisms of thromboinflammation and the relationship between innate immune cells and thrombosis. Monocytes are activated by aPL into a proinflammatory and procoagulant phenotype, producing proinflammatory cytokines such as tumor necrosis factor α, interleukin 6, as well as tissue factor. Important cellular signaling pathways involved are the NF-κB-pathway, mammalian target of rapamycin (mTOR) signaling, and the NOD-, LRR-, and pyrin domain-containing protein 3 inflammasome. All of these may serve as future therapeutic targets. Neutrophils produce neutrophil extracellular traps in response to aPL, and this leads to thrombosis. Thrombosis in APS also stems from increased interaction of neutrophils with endothelial cells through P-selectin glycoprotein ligand-1. NETosis can be targeted not only with several experimental therapeutics, such as DNase, but also through the redirection of current therapies such as defibrotide and the antiplatelet agent dipyridamole. Activation of platelets by aPL leads to a procoagulant phenotype. Platelet-leukocyte interactions are increased, possibly mediated by increased levels of soluble P-selectin and soluble CD40-ligand. Platelet-directed future treatment options involve the inhibition of several platelet receptors activated by aPL, as well as mTOR inhibition. This review discusses mechanisms underlying thromboinflammation in APS that present targetable therapeutic options, some of which may be generalizable to other thromboinflammatory diseases.

A prospective marker for the prediction of postoperative deep venous thrombosis: Neutrophil extracellular traps

Deep venous thrombosis (DVT) is a common medical complication in patients with lumbar fractures. The current study aimed to investigate the predictive value of neutrophil extracellular traps (NETs) in postoperative DVT formation in patients with lumbar fractures and to develop a nomogram relating clinical admission information for prediction. Patients who underwent open reduction and pedicle screw internal fixation in the treatment of single-segment lumbar fracture in the Department of Spine Surgery, the First Affiliated Hospital of Nanjing Medical University, from December 2020 to June 2022 were enrolled in this study. Baseline data and laboratory results were collected from enrollees, and the primary study endpoint event was the occurrence of DVT in patients after surgery. Multivariable logistic regression analysis was used to identify risk factors associated with higher odds of DVT after surgery. A nomogram was constructed using the results of the multivariable model. The calibration plot and receiver operating characteristics (ROC) curve were used to show the satisfactory predictive capacity of the model. Of these 393 patients who did not have DVT preoperatively, 79 patients developed it postoperatively, and 314 did not, respectively. Multivariate analysis showed that higher body mass index (BMI) (BMI between 24 and 28: RR = 1.661, 95% CI = 0.891-3.094; BMI ≤28: RR = 5.625, 95% CI = 2.590-12.217; reference: BMI <24), neutrophils (RR = 1.157, 95% CI 1.042-1.285), D-dimer (RR = 1.098, 95% CI 1.000-1.206), and citrullinated histone H3 (CitH3) (RR = 1.043, 95% CI 1.026-1.060) were independent risk factors for postoperative DVT. Using the multivariable analysis, we then constructed a nomogram to predict DVT, which was found to have an area under the curve of 0.757 (95% CI = 0.693-0.820). Calibration plots also showed the satisfied discrimination and calibration of the nomogram. In conclusion, patients with lumbar fractures with postoperative DVT had higher levels of NETs in the circulation preoperatively compared to those without postoperative DVT. Furthermore, based on BMI, D-dimer, neutrophils, and CitH3, we developed a predictive model to predict postoperative DVT incidence in these patients.

A prospective cohort study of dynamic cell-free DNA elevation during cardiac surgery with cardiopulmonary bypass

Cardiac surgery and cardiopulmonary bypass (CPB) are associated with a systemic inflammatory reaction that occasionally induces a life-threatening organ dysfunction caused by the dysregulated host response to the damage-associated molecular patterns (DAMPs). In severe inflammation, cell-free DNA (cfDNA) and histones are released by inflammatory cells and damaged tissue and act as DAMPs. We sought to characterize the changes in circulating cell-free DNA (cfDNA) levels during CPB. Primary outcomes were renal failure, ventilation time (>18 hr), length of stay (LOS) in the intensive care unit (ICU) (>48hr), hospital LOS (>15 days), and death. We looked for associations with blood tests and comparison to standard scores. In a prospective cohort study, we enrolled 71 patients undergoing non-emergent coronary artery bypass grafting. Blood was drawn at baseline, 20 and 40 minutes on CPB, after cross-clamp removal, and 30 minutes after chest closure. cfDNA was measured by our fast fluorescent method. Baseline cfDNA levels [796 (656–1063) ng/ml] increased during surgery, peaked after cross-clamp removal [2403 (1981–3357) ng/ml] and returned to baseline at recovery. The difference in cfDNA from 20 to 40 minutes on CPB (ΔcfDNA 40–20) inversely correlated with peripheral vascular disease (PVD), longer ventilation time, and longer ICU and hospital length of stay (LOS). Receiver operating characteristic (ROC) curve of ΔcfDNA 40–20 for long ICU-LOS (>48hr) was with an area under the curve (AUC) of 0.738 (p = 0.022). ROC AUC of ΔcfDNA 40–20 to long Hospital LOS (>15 days) was 0.787 (p = 0.006). Correction for time on CPB in a multivariate logistic regression model improved ROC-AUC to 0.854 (p = 0.003) and suggests that ΔcfDNA 40–20 is an independent risk factor. To conclude, of measured parameters, including STS and Euroscore, the predictive power of ΔcfDNA 40–20 was the highest. Thus, measurement of ΔcfDNA 40–20 may enable early monitoring of patients at higher risk. Further studies on the mechanism behind the negative association of ΔcfDNA 40–20 with PVD and outcomes are warranted.

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.

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.

Ginsenoside Rg5 allosterically interacts with P2RY12 and ameliorates deep venous thrombosis by counteracting neutrophil NETosis and inflammatory response

Background

Deep venous thrombosis (DVT) highly occurs in patients with severe COVID-19 and probably accounted for their high mortality. DVT formation is a time-dependent inflammatory process in which NETosis plays an important role. However, whether ginsenoside Rg5 from species of Panax genus could alleviate DVT and its underlying mechanism has not been elucidated.

Methods

The interaction between Rg5 and P2RY₁₂ was studied by molecular docking, molecular dynamics, surface plasmon resonance (SPR), and molecular biology assays. The preventive effect of Rg5 on DVT was evaluated in inferior vena cava stasis–induced mice, and immunocytochemistry, Western blot, and calcium flux assay were performed in neutrophils from bone marrow to explore the mechanism of Rg5 in NETosis via P2RY₁₂.

Results

Rg5 allosterically interacted with P2RY₁₂, formed stable complex, and antagonized its activity via residue E188 and R265. Rg5 ameliorated the formation of thrombus in DVT mice; accompanied by decreased release of Interleukin (IL)-6, IL-1β, and tumor necrosis factor-α in plasma; and suppressed neutrophil infiltration and neutrophil extracellular trap (NET) release. In lipopolysaccharide- and platelet-activating factor–induced neutrophils, Rg5 reduced inflammatory responses via inhibiting the activation of ERK/NF-κB signaling pathway while decreasing cellular Ca²⁺ concentration, thus reducing the activity and expression of peptidyl arginine deiminase 4 to prevent NETosis. The inhibitory effect on neutrophil activity was dependent on P2RY₁₂.

Conclusions

Rg5 could attenuate experimental DVT by counteracting NETosis and inflammatory response in neutrophils via P2RY₁₂, which may pave the road for its clinical application in the prevention of DVT-related disorders.

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.

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.

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.

Circulating cell free DNA and citrullinated histone H3 as useful biomarkers of NETosis in endometrial cancer

BACKGROUND

Cancer mortality is mainly caused by organ failure and thrombotic events. It has been demonstrated that NETosis, a chromatin release mechanism implemented by neutrophils, may contribute to these lethal systemic effects. Our aim was to investigate NETosis biomarkers in endometrial cancer (EC).

METHODS

The experiments were conducted on 21 healthy subjects (HS) with no gynecological conditions, and on 63 EC patients. To assess the presence of NETosis features, IHC and IF was performed using antibodies against citrullinated histone H3 (citH3), neutrophil elastase (NE) and histone 2B. Serum levels of cell free DNA (cfDNA), cell free mitochondrial DNA (cfmtDNA) and citH3 were measured by qPCR using one microliter of deactivated serum, and by ELISA assay respectively. Fragmentation pattern of serum cfDNA was analyzed using the Agilent 2100 Bioanalyzer and High Sensitivity DNA Chips. Receiver operating characteristic (ROC) analysis was used to identify a cut off for cfDNA and cfmtDNA values able to discriminate between ECs and HSs. Correlation analysis and multiple correspondence analysis (MCA) between cfDNA, mtcfDNA, citH3 and blood parameters were used to identify the potential association among serum parameters in EC grades.

RESULTS

We demonstrated the presence of NETosis features in tissues from all EC grades. Serum cfDNA and cfmtDNA levels discriminate ECs from HSs and a direct correlation between citH3 and cfDNA content and an inverse correlation between cfmtDNA and citH3 in EC sera was observed, not detectable in HSs. MCA indicates cfDNA, cfmtDNA and citH3 as features associated to G1 and G2 grades. A correlation between increased levels of cfDNA, citH3 and inflammation features was found. Finally, serum nucleosomal cfDNA fragmentation pattern varies in EC sera and correlates with increased levels of cfDNA, citH3, lymphocytes and fibrinogen.

CONCLUSION

Our data highlight the occurrence of NETosis in EC and indicate serum cfDNA and citH3 as noninvasive biomarkers of tumor-induced systemic effects in endometrial cancer.

Integrated GWAS and Gene Expression Suggest ORM1 as a Potential Regulator of Plasma Levels of Cell-Free DNA and Thrombosis Risk

Plasma cell-free DNA (cfDNA) is a surrogate marker of neutrophil extracellular traps (NETs) that contribute to immunothrombosis. There is growing interest about the mechanisms underlying NET formation and elevated cfDNA, but little is known about the factors involved. We aimed to identify genes involved in the regulation of cfDNA levels using data from the Genetic Analysis of Idiopathic Thrombophilia (GAIT-2) Project.

Imputed genotypes, whole blood RNA-Seq data, and plasma cfDNA quantification were available for 935 of the GAIT-2 participants from 35 families with idiopathic thrombophilia. We performed heritability and GWAS analysis for cfDNA. The heritability of cfDNA was 0.26 ( p  = 3.7 × 10 ⁻⁶ ), while the GWAS identified a significant association (rs1687391, p  = 3.55 × 10 ⁻¹⁰ ) near the ORM1 gene, on chromosome 9. An eQTL (expression quantitative trait loci) analysis revealed a significant association between the lead GWAS variant and the expression of ORM1 in whole blood ( p  = 6.14 × 10 ⁻⁹ ). Additionally, ORM1 expression correlated with levels of cfDNA ( p  = 4.38 × 10 ⁻⁴ ). Finally, genetic correlation analysis between cfDNA and thrombosis identified a suggestive association ( ρ_g  = 0.43, p  = 0.089).

All in all, we show evidence of the role of ORM1 in regulating cfDNA levels in plasma, which might contribute to the susceptibility to thrombosis through mechanisms of immunothrombosis.

The Citrullination-Neutrophil Extracellular Trap Axis in Chronic Diseases

Citrullination of proteins is crucial for the formation of neutrophil extracellular traps (NETs) − strands of nuclear DNA expulsed in the extracellular environment along with antimicrobial proteins in order to halt the spread of pathogens. Paradoxically, NETs may be immunogenic and contribute to inflammation. It is known that for the externalization of DNA, a group of enzymes called peptidyl arginine deiminases (PADs) is required. Current research often looks at citrullination, NET formation, PAD overexpression, and extracellular DNA (ecDNA) accumulation in chronic diseases as separate events. In contrast, we propose that citrullination can be viewed as the primary mechanism of autoimmunity, for instance by the formation of anti-citrullinated protein antibodies (ACPAs) but also as a process contributing to chronic inflammation. Therefore, citrullination could be at the center, connecting and impacting multiple inflammatory diseases in which ACPAs, NETs, or ecDNA have already been documented. In this review, we aimed to highlight the importance of citrullination in the etiopathogenesis of a number of chronic diseases and to explore the diagnostic, prognostic, and therapeutic potential of the citrullination-NET axis.

Generation of neutrophil extracellular traps in patients with acute liver failure is associated with poor outcome

BACKGROUND AND AIMS

Acute liver failure (ALF) is characterized by significant changes in the hemostatic system and by systemic inflammation. The formation of neutrophil extracellular traps (NETs), in which an activated neutrophil expels its DNA, histones, and granular enzymes, such as myeloperoxidase (MPO), has been associated with immune-mediated and thrombotic diseases. We hypothesized that formation of NETs in patients with ALF contributes to progression of disease.

APPROACH AND RESULTS

A total of 676 patients with ALF (international normalized ratio [INR], ≥1.5) or severe acute liver injury (ALI; INR, ≥2.0) were recruited from the U.S. ALF Study Group Registry between 2011 and 2018, of whom 308 patients (45.6%) had acetaminophen-induced ALF. Up to 21 days after admission, 483 patients (71.5%) survived without liver transplantation (LT). Levels of cell-free DNA (cfDNA) and the specific NET marker MPO-DNA complexes were measured in plasma samples obtained on admission and compared to levels in healthy controls. In addition, liver tissue obtained at transplantation of 20 ALF patients was stained for NETs. Levels of cfDNA were 7.1-fold, and MPO-DNA complexes 2.5-fold, higher in patients with ALF compared to healthy controls. cfDNA levels were not associated with 21-day transplant-free survival, but were higher in those patients with more-severe disease on admission, as reflected by various laboratory and clinical parameters. MPO-DNA levels were 30% higher in patients with ALF who died or required urgent LT. Liver tissue of ALF patients stained positive for NETs in 12 of 18 evaluable patients.

CONCLUSIONS

Here, we provide evidence for NET formation in patients with ALF. Elevated plasma levels of MPO-DNA complexes in patients with ALF were associated with poor outcome, which suggests that NET formation contributes to disease progression.

Neutrophil Extracellular Traps in Atherosclerosis and Thrombosis

Despite effective therapeutic and preventive strategies, atherosclerosis and its complications still represent a substantial health burden. Leukocytes and inflammatory mechanisms are increasingly recognized as drivers of atherosclerosis. Neutrophil granulocytes within the circulation were recently shown to undergo neutrophil extracellular trap (NET) formation, linking innate immunity with acute complications of atherosclerosis. In this chapter, we summarize mechanisms of NET formation, evidence for their involvement in atherosclerosis and thrombosis, and potential therapeutic regimens specifically targeting NET components.

Hypercoagulability in Patients with Non-Alcoholic Fatty Liver Disease (NAFLD): Causes and Consequences

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and it is anticipated that it could become even more prevalent in parallel with an increase in the incidence of metabolic diseases closely related to NAFLD, such as obesity, type II diabetes, dyslipidemia, and arterial hypertension. In addition to liver impairment, NAFLD is associated with cardiovascular diseases. Fibrosis, atherosclerosis, and venous thrombosis are basically the pathogenic mechanisms behind these clinical manifestations, and all are plausibly associated with hypercoagulability that may, in turn, develop because of an imbalance of pro- vs. anticoagulants and the presence of such procoagulant molecular species as microvesicles, neutrophil extracellular traps (NETs), and inflammation. The assessment of hypercoagulability by means of thrombin generation is a global procedure that mimics the coagulation process occurring in vivo much better than any other coagulation test, and is considered to be the best candidate laboratory tool for assessing, with a single procedure, the balance of coagulation in NAFLD. In addition to defining the state of hypercoagulability, the assessment of thrombin generation could also be used to investigate, in clinical trials, the best approach (therapeutic and/or lifestyle changes) for minimizing hypercoagulability and, hence, the risk of cardiovascular diseases, progression to atherosclerosis, and liver fibrosis in patients with NAFLD.

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

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

Anti-TNF-α Treatment Reduces the Baseline Procoagulant Imbalance of Patients With Inflammatory Bowel Diseases

BACKGROUND

Inflammatory bowel diseases (IBD) are characterized by an increased thrombosis risk of uncertain etiology. Coagulation derangement arising from inflammation may be a triggering factor. We hypothesized that strong inflammation inhibitors (eg, anti-tumor necrosis factor-α drugs) may affect coagulation.

METHODS

Forty patients with IBD were compared with 57 control patients for coagulation factors and endogenous thrombin potential (ETP), the latter being the most sensitive marker of in vivo pro- and anticoagulation balance. We measured ETP in the presence and absence of thrombomodulin (the physiologic protein C [PC] activator). Coagulation at different timepoints was also assessed for 28 of these patients during infliximab treatment.

RESULTS

The median ETP (nM thrombin × minutes) and range (minimum-maximum) were each higher in patients at baseline than in control patients in both the absence (2120 [1611-3041] vs 1865 [1270-2337]) and the presence (1453 [464-2522] vs 831 [104-1741]) of thrombomodulin. The ETP ratio (with/without thrombomodulin) was high at baseline (0.73 [0.21-0.90] vs 0.45 [0.07-0.85]). The ETP and ETP ratio declined during treatment and were significantly lower at the end than at baseline. Factor (F) VIII and fibrinogen, which were high at baseline, decreased during treatment and at the end were significantly lower than at baseline. The FVIII/PC ratio, which was high in patients at baseline, declined during treatment and at the end was lower than at baseline. C-reactive protein recorded at the end of treatment was lower than at baseline.

CONCLUSIONS

Patients with IBD have a procoagulant imbalance as shown by increased ETP at baseline. The ETP decreases during treatment with infliximab, which is related to decreased FVIII and FVIII/PC ratio. This effect is also related to the improvement of inflammation as shown by decreased fibrinogen and C-reactive protein.

Stabilin-2 deficiency increases thrombotic burden and alters the composition of venous thrombi in a mouse model

BACKGROUND

Stabilin-2 is an endocytic scavenger receptor that mediates the clearance of glycosaminoglycans, phosphatidylserine-expressing cells, and the von Willebrand factor-factor VIII (FVIII) complex. In a genome-wide screening study, pathogenic loss-of-function variants in the human STAB2 gene associated with an increased incidence of unprovoked venous thromboembolism (VTE). However, the specific mechanism(s) by which stabilin-2 deficiency influences the pathogenesis of VTE is unknown.

OBJECTIVES

The aim of this study was to assess the influence of stabilin-2 on deep vein thrombosis (DVT) and to characterize the underlying prothrombotic phenotype of stabilin-2 deficiency in a mouse model.

METHODS

DVT was induced using the inferior vena cava (IVC) stenosis model in two independent cohorts (littermates and non-littermates) of wild-type (Stab2+/+ ) and stabilin-2 (Stab2-/- )-deficient mice. Thrombus structure and contents were quantified by immunohistochemistry. Plasma procoagulant activity was assessed and complete blood counts were performed.

RESULTS

Incidence of thrombus formation was not altered between Stab2+/+ and Stab2-/- mice. When thrombi were formed, Stab2-/- mice developed significantly larger thrombi than Stab2+/+ controls. Thrombi from Stab2-/- mice contained significantly more leukocytes and citrullinated histone H3 than Stab2+/+ thrombi. Stab2-/- mice had increased FVIII activity. Circulating levels of monocytes and granulocytes were significantly elevated in Stab2-/- mice, and Stab2-/- mice had elevated plasma cell-free DNA 24 hours post-IVC stenosis compared to their Stab2+/+ counterparts.

CONCLUSIONS

These data suggest that stabilin-2 deficiency associates with a prothrombotic phenotype involving elevated levels of neutrophil extracellular trap-releasing leukocytes coupled with endogenous procoagulant activity, resulting in larger and qualitatively distinct venous thrombi.

The relation between fibrinogen level, neutrophil activity and nucleosomes in the onset of disseminated intravascular coagulation in the critically ill

BACKGROUND

Nucleosomes and neutrophil extracellular traps (NETs) are important in the pathophysiology of disseminated intravascular coagulation (DIC). Fibrinogen, as an acute phase reactant, may be protective by engaging neutrophils. We hypothesize that DIC can occur when NET formation becomes uncontrolled in relation to low fibrinogen levels.

PATIENTS/METHOD

The ratio of both circulating nucleosomes and human neutrophil elastase alpha-1-antitrypsine complexes (HNE-a1ATc) to fibrinogen was correlated to thrombocytopenia, DIC and organ failure in 64 critically ill coagulopathic patients.

RESULTS

A high nucleosome to fibrinogen ratio correlated with thrombocytopenia and organ failure (ρ -0.391, p 0.01 and ρ 0.556, p 0.01, respectively). A high HNE-a1ATc to fibrinogen ratio correlated with thrombocytopenia, DIC and organ failure (ρ -0.418, p 0.01, ρ 0.391, p 0.01 and ρ 0.477, p 0.01 respectively).

CONCLUSION

These findings support the hypothesis that fibrinogen is protective against DIC by counterbalancing excessive neutrophil activation.

Risk of Venous Thromboembolism in Hospitalized Patients with Acute Ischemic Stroke Versus Other Neurological Conditions

BACKGROUND

The mechanism of increased risk of venous thromboembolism (VTE) after acute ischemic stroke (AIS) is unclear. In this study, we aimed to evaluate the risk of VTE in hospitalizations due to AIS as compared to those due to non-vascular neurological conditions. We also aimed to assess any potential association between VTE risk and the use of intravenous thrombolysis (rtPA) among hospitalizations with AIS.

MATERIALS AND METHODS

In this case-control study, data were obtained from the Nationwide Inpatient Sample 2016-2018. Propensity score matching was used to adjust for the baseline differences between the groups. Logistic regression analysis was used to compare the risk of VTE.

RESULTS

We identified 1,541,685 hospitalizations due to AIS and 1,453,520 hospitalizations due to non-vascular neurological diagnoses that served as controls. After propensity score matching, 640,560 cases with AIS and corresponding well-matched controls were obtained. Hospitalizations due to AIS had higher odds of VTE as compared to the controls [odds ratio (OR) 1.50, 95% confidence interval (CI) 1.40-1.60, P<0.001]. Among hospitalizations with AIS, 184,065 (11.9%) got rtPA. The odds of VTE were lower among the AIS hospitalizations that received rtPA as compared to those that did not (OR 0.89, 95% CI 0.79-0.99, P0.035).

CONCLUSION

Hospitalizations due to AIS have a higher risk of VTE as compared to the non-vascular neurological controls. Among AIS cases, the risk of VTE is lower among patients treated with rtPA. These epidemiological findings support the hypothesis that the risk of VTE after AIS might be partly mediated by an intrinsic pro-coagulant state.

Neutrophil activation and circulating neutrophil extracellular traps are increased in venous thromboembolism patients for at least one year after the clinical event

Neutrophil activation and neutrophil extracellular traps (NETs) have been associated with the pathogenesis of venous thromboembolism (VTE). Considering VTE-associated chronic sequelae, which suggest that some pathological mechanisms remain after the acute episode, we investigated whether neutrophil activation is increased in patients with a prior VTE at least one year before this investigation. Thirty-seven patients with prior VTE and 37 individuals with no history of VTE were included. Neutrophil activity was evaluated by the expression of the adhesive molecule activation-specific epitopes LFA-1 (CD11a) and MAC-1 (CD11b), chemotaxis, reactive oxygen species (ROS) and by MPO-DNA complexes as markers of NETs. The adhesive molecules sICAM-1 and sVCAM-1, involved in the cross talk between neutrophil and endothelial cells, were also evaluated. Patient neutrophils presented increased CD11a expression before and after TNF-α stimulus, whereas increased CD11b expression was observed only after TNF-α stimulus, as compared to controls. Neutrophil chemotaxis on both, basal state and after IL-8 stimulus, on circulating levels of sICAM-1 and sVCAM-1, and on MPO-DNA complexes were also increased in VTE patients. ROS release was similar between patients and controls. This is, to our knowledge, the first study to investigate neutrophil inflammatory activity in VTE patients a long period after an acute event (approximately 2 years). The results showed altered neutrophil activation patterns in these patients. While activated neutrophils can cause endothelial activation and injury, the activated endothelium can induce the release of NETs with consequent endothelial cytotoxicity, creating a vicious cycle of activation between neutrophils and endothelium that can lead to thrombosis.

Neutrophil extracellular traps and neutrophil-derived mediators as possible biomarkers in bronchial asthma

Neutrophils (PMNs) contain and release a powerful arsenal of mediators, including several granular enzymes, reactive oxygen species (ROS) and neutrophil extracellular traps (NETs). Although airway neutrophilia is associated with severity, poor response to glucocorticoids and exacerbations, the pathophysiological role of neutrophils in asthma remains poorly understood. Twenty-four patients with asthma and 22 healthy controls (HCs) were prospectively recruited. Highly purified peripheral blood neutrophils (> 99%) were evaluated for ROS production and activation status upon stimulation with lipopolysaccharide (LPS), N-formylmethionyl-leucyl-phenylalanine (fMLP) and phorbol 12-myristate 13-acetate (PMA). Plasma levels of myeloperoxidase (MPO), CXCL8, matrix metalloproteinase-9 (MMP-9), granulocyte–monocyte colony-stimulating factor (GM-CSF) and vascular endothelial growth factor (VEGF-A) were measured by ELISA. Plasma concentrations of citrullinated histone H3 (CitH3) and circulating free DNA (dsDNA) were evaluated as NET biomarkers. Activated PMNs from asthmatics displayed reduced ROS production and activation status compared to HCs. Plasma levels of MPO, MMP-9 and CXCL8 were increased in asthmatics compared to HCs. CitH3 and dsDNA plasma levels were increased in asthmatics compared to controls and the CitH3 concentrations were inversely correlated to the % decrease in FEV₁/FVC in asthmatics. These findings indicate that neutrophils and their mediators could have an active role in asthma pathophysiology.

Venous thromboembolism

Venous thromboembolism, comprising both deep vein thrombosis and pulmonary embolism, is a chronic illness that affects nearly 10 million people every year worldwide. Strong provoking risk factors for venous thromboembolism include major surgery and active cancer, but most events are unprovoked. Diagnosis requires a sequential work-up that combines assessment of clinical pretest probability for venous thromboembolism using a clinical score (eg, Wells score), D-dimer testing, and imaging. Venous thromboembolism can be considered excluded in patients with both a non-high clinical pretest probability and normal D-dimer concentrations. When required, ultrasonography should be done for a suspected deep vein thrombosis and CT or ventilation-perfusion scintigraphy for a suspected pulmonary embolism. Direct oral anticoagulants (DOACs) are the first-line treatment for almost all patients with venous thromboembolism (including those with cancer). After completing 3-6 months of initial treatment, anticoagulation can be discontinued in patients with venous thromboembolism provoked by a major transient risk factor. Patients whose long-term risk of recurrent venous thromboembolism outweighs the long-term risk of major bleeding, such as those with active cancer or men with unprovoked venous thromboembolism, should receive indefinite anticoagulant treatment. Pharmacological venous thromboembolism prophylaxis is generally warranted in patients undergoing major orthopaedic or cancer surgery. Ongoing research is focused on improving diagnostic strategies for suspected deep vein thrombosis, comparing different DOACs, developing safer anticoagulants, and further individualising approaches for the prevention and management of venous thromboembolism.

Pro-coagulant imbalance in patients with community acquired pneumonia assessed on admission and one month after hospital discharge

OBJECTIVES

Patients hospitalized because of community-acquired-pneumonia (CAP) are at risk of cardiovascular diseases. Although plasma procoagulant imbalance play a role, mechanisms are not completely understood. We aimed to investigate whether there is a measurable state of procoagulant imbalance following inflammation determined by CAP.

METHODS

We analyzed blood from 51 CAP patients at admission and 51 healthy subjects (HS) for (i) pro and anticoagulants, (ii) thrombin generation (TG) with or without thrombomodulin (TM), which is the physiologic activator of the protein C anticoagulant pathway and(iii) by assessing the ratio between von Willebrand-factor (VWF) and its protease ADAMTS13. Thirty patients were re-analyzed one month after discharge when CAP was resolved.

RESULTS

Median levels of TG parameters, including the endogenous thrombin potential (ETP), the ETP-TM-ratio (with/without TM), peak-thrombin and velocity index were higher in patients at baseline than HS. In particular, the median (IQR) ETP-TM-ratio in patients vs. HS was 0.88 (0.83-0.91) vs. 0.63 (0.48-0.71), p<0.001. Factor (F)VIII, a potent procoagulant involved in TG was higher in patients at baseline than HS [195 U/dL (100-388) vs. 127(108-145)], p<0.001]. The ratio of VWF/ADAMTS13 was higher at baseline than HS. Cumulatively, the findings indicate a state of pro-coagulant imbalance, which (although reduced), remained high [i.e., ETP-TM-ratio, 0.80 (0.74-0.84); FVIII, 152 U/dL (122-190)] one month after discharge when the infection was resolved.

CONCLUSIONS

Patients with CAP possess a state of pro-coagulant imbalance, which remains substantially high, even when the infection is resolved. The findings suggest CAP patients as candidates for antithrombotic prophylaxis even after the resolution of infection. Clinical trials are warranted to assess the benefit/risk ratio of prophylaxis extension.

Venous thromboembolism in hospital emergency room. A retrospective study on climatic effect

Several cardiovascular conditions exhibit seasonality in frequency and mortality, but little is known about the seasonality of Venous ThromboEmbolism (VTE), a very relevant medical condition, and seasonal influences are still conflicting. Patients having co-morbidities, individual suffered from dyspnea, swelling, edema of lower limb, pain (chest, lower limbs) are admitted frequently to the hospital emergency room (HER), particularly. Both mark a potential risk for VTE, that can be increased also by seasonality. A four years retrospective analysis (2016-2019) was carried out in individuals and patients admitted to the HER of the Hospital of Catania (a Mediterranean city of Sicily, Italy) to evaluate the VTE frequency and its seasonal differences, common symptoms, potential usage of some common laboratory tests. Dyspnea, swelling, edema of lower limb and pain (chest, lower limbs) were considered to suspect pulmonary embolism (PE) or for deep vein thrombosis of lower limb (DVT). Platelet count, platelet volume, fibrinogen, C-reactive protein, and D-dimer were considered. VTE frequency per year was 2.9/10,000 (2016), 4.9/10,000 (2017) 3.6/10,000 (2018), and 5.1/10,000 (2019) respectively. Dyspnea was highly frequent for PE, edema and lower limb pain were frequent in DVT patients. Fibrinogen, C reactive protein, and D-dimer values were found raised in all the VTE patients. Platelet volume was found higher in DVT than PE VTE events that occurred in warm periods were modestly greater (57 VTE: 38 DVT, 19 PE) compared to cold months (52 VTE: 34 DVT, 18 PE). Our results could be explained by the increased sweating due to the high temperatures, which in turn, can affect both on plasma concentration and on hematocrit value coupled to the reduction in atmospheric pressure determining both a hyper-coagulative condition. Climate seasonal characteristics, and environmental conditions in Catania city (Sicily) may be as reasonable items in expecting on different VTE rates in warm period compared to cold. This study highlights no specific symptoms, and confirms the common lab tests for individuals and patients admitted to HER as simple and helpful tools in initiating none or mini-invasive diagnostic strategy for the VTE. Finally, the climate/seasonality coupled with latitude can have a direct influence on the incidence of DVT.

The impact of neutrophil extracellular traps on deep venous thrombosis in patients with traumatic fractures

BACKGROUND

Deep venous thrombosis (DVT) is the most common complication in patients with traumatic fractures. The neutrophil extracellular traps (NETs) can promote thrombus formation. In this prospective study, we investigated the role of NETs in thrombosis in patients with traumatic fractures to evaluate whether the biomarkers of NETs can be used to help predict the risk of thrombosis.

METHODS

Traumatic fracture patients were enrolled in this prospective observational cohort study. Healthy controls (Control); patients with lower extremity fractures who neither present with nor develop DVT (Trauma non-DVT); patients with lower extremity fractures who do not present with DVT but do develop DVT (Trauma DVT); and patients with lower extremity fractures who present with DVT (DVT) were included. NETs biomarker levels of Citrullinated Histone H3 (H3Cit), cell-free DNA (cfDNA) and nucleosomes in the plasma were determined. The D-dimer and fibrin(-ogen) degradation products (FDP) level in plasma was measured. Statistical analysis of the test results was performed to assess changes in NETs biomarker levels during thrombosis in patients with traumatic fractures.

RESULTS

The H3Cit levels in the DVT group were significantly greater than in the Trauma non-DVT group and Trauma DVT group (1.88(1.11, 3.35) ng/ml Vs 0.38(0.10, 1.17) ng/ml, P ≤ 0.05). The level of cfDNA was significantly greater in patients with traumatic fractures and was higher after thrombosis than before. The levels of D-dimer in the DVT, Trauma DVT, and Trauma non-DVT groups were significantly greater than in the Control group (5.11(3.97, 8.11) mg/l; 6.12(2.59, 18.49) mg/l; 2.99(0.99, 9.02) mg/l Vs 0.18(0.08,0.24) mg/l, P < 0.05). The distribution of FDP levels in each group was similar to that of D-dimer. Data are presented as medians (25th percentile, 75th percentile).

CONCLUSIONS

NETs released by neutrophils are involved in the formation of DVTs in patients with traumatic fractures. H3Cit and cfDNA can assist the diagnosis of DVT in patients with traumatic fractures.

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

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

Platelets: Underestimated Regulators of Autoinflammation in Psoriasis

Platelets have long been known as mediators of hemostasis and, more recently, as mediators of thromboinflammation, although their physiopathological role has mostly been investigated in the context of disease of internal organs, such as liver and kidney, or systemic disorders. Of late, exciting recent data suggest that platelets may also play a role in inflammation at distal sites such as the skin: recent studies show that platelets, by engaging polymorphonuclear neutrophils (PMNs), contribute to local inflammation in the frequent skin disorder, psoriasis. In an experimental model, systemic depletion of platelets drastically attenuated skin inflammation by preventing PMN infiltration of the skin. A broader role of platelets in different types of skin inflammation is therefore likely, and in this paper, we specifically review recent advances in psoriasis. Special emphasis is given to the crosstalk with systemic platelet effects, which may be of interest in psoriasis-related cardiovascular comorbidities. Furthermore, we discuss the potential for platelet-centered interventions in the therapy for psoriasis.

The impact of thrombo-inflammation on the cerebral microcirculation

The intertwined processes of thrombosis and inflammation (termed "thrombo-inflammation") are significant drivers of cerebrovascular diseases, and as such, they represent prime targets for drug discovery programs focusing on treatment and management of cerebrovascular diseases. Most cerebrovascular events result from chronic systemic microcirculatory dysfunction due to underlying conditions, for example, hypertension, diabetes mellitus, coronary artery disease, dyslipidemia, and sickle cell disease. Immune cells especially neutrophils play a critical role in the onset and maintenance of neuroinflammatory responses in the microcirculation. Neutrophils have the ability to drive both inflammatory and anti-inflammatory/pro-resolution effects depending on the underlying vascular state (physiological vs. pathological). In this article, we highlight the pathophysiological role of neutrophils in stroke and discuss ongoing pharmacotherapeutic strategies that are focused on identifying potential therapeutic targets for enhancing neuroprotection, mitigating inflammatory pathways, and enabling resolution.

Cellular fibronectin promotes deep vein thrombosis in diet-induced obese mice

BACKGROUND

Overweight and obesity are significant risk factors for deep vein thrombosis (DVT). Cellular fibronectin containing extra domain A (Fn-EDA), an endogenous ligand for toll-like-receptor 4 (TLR4), contributes to thrombo-inflammation. The role of Fn-EDA in the modulation of DVT is not elucidated yet.

OBJECTIVE

To determine whether Fn-EDA promotes DVT in the context of diet-induced obesity.

METHODS

Wild-type (WT) and Fn-EDA-deficient mice were either fed control or high-fat (HF) diet for 12 weeks. DVT was induced by inferior vena cava (IVC) stenosis and evaluated after 48 hours. Cellular Fn-EDA levels in the plasma of venous thromboembolism (VTE) patients were measured by sandwich ELISA.

RESULTS

We found that cellular Fn-EDA levels were significantly elevated in VTE patients' plasma and positively correlated with body mass index. HF diet-fed WT mice exhibited increased DVT susceptibility compared with control diet-fed WT mice. In contrast, HF diet-fed Fn-EDA-deficient mice exhibited significantly reduced thrombus weight and decreased incidence (%) of DVT compared with HF diet-fed WT mice concomitant with reduced neutrophil content and citrullinated histone H3-positive cells (a marker of NETosis) in IVC thrombus. Exogenous cellular Fn-EDA potentiated NETosis in neutrophils stimulated with thrombin-activated platelets via TLR4. Genetic deletion of TLR4 in Fn-EDA+ mice (constitutively express Fn-EDA in plasma and tissues), but not in Fn-EDA-deficient mice, reduced DVT compared with respective controls.

CONCLUSION

These results demonstrate a previously unknown role of Fn-EDA in the DVT exacerbation, which may be an essential mechanism promoting DVT in the setting of diet-induced obesity.

Cytokine Storm as a Cellular Response to dsDNA Breaks: A New Proposal

Pathogenesis of cytokine storm is poorly understood. In this article we propose a new mechanism and suggest innovative therapeutic avenues for its prevention. We have reported that particles of cell-free chromatin (cfCh) that are released from the billions of cells that die in the body everyday can illegitimately integrate into genomes of healthy cells to trigger dsDNA breaks. The latter leads to apoptosis and/or intense activation of inflammatory cytokines in the affected cells. We hypothesise that a similar phenomenon of dsDNA breaks and inflammation is involved in cytokine storm. The abundant cfCh particles that are released from dying host cells following viral/microbial invasion initiate a cascading effect of more cell death resulting in a vicious cycle of further DNA damage, apoptosis and hyper-inflammation which culminate in cytokine storm. We propose that this unrelenting vicious cycle of cellular DNA damage and cytokine storm may be the underlying cause of high mortality from severe COVID-19. We discuss results of our preclinical studies wherein we have shown that endotoxin induced cytokine storm in mice can be reversed by three different agents that have the ability to inactivate cfCh. These agents may be worthy of investigation in clinical trials to reduce mortality from COVID-19.