Serum Neutrophil Extracellular Traps Research Articles

Complement-Mediated Two-Step NETosis: Serum-Induced Complement Activation and Calcium Influx Generate NADPH Oxidase-Dependent NETs in Serum-Free Conditions.

The complement system and neutrophils play crucial roles in innate immunity. Neutrophils release neutrophil extracellular traps (NETs), which are composed of decondensed DNA entangled with granular contents, as part of their innate immune function. Mechanisms governing complement-mediated NET formation remain unclear. In this study, we tested a two-step NETosis mechanism, as follows: classical complement-mediated neutrophil activation in serum and subsequent NET formation in serum-free conditions, using neutrophils from healthy donors, endothelial cells, and various assays (Fluo-4AM, DHR123, and SYTOX), along with flow cytometry and confocal microscopy. Our findings reveal that classical complement activation on neutrophils upregulated the membrane-anchored complement regulators CD46, CD55, and CD59. Additionally, complement activation increased CD11b on neutrophils, signifying activation and promoting their attachment to endothelial cells. Complement activation induced calcium influx and citrullination of histone 3 (CitH3) in neutrophils. However, CitH3 formation alone was insufficient for NET generation. Importantly, NET formation occurred only when neutrophils were in serum-free conditions. In such environments, neutrophils induced NADPH oxidase-dependent reactive oxygen species (ROS) production, leading to NET formation. Hence, we propose that complement-mediated NET formation involves a two-step process, as follows: complement deposition, neutrophil priming, calcium influx, CitH3 formation, and attachment to endothelial cells in serum. This is followed by NADPH-dependent ROS production and NET completion in serum-free conditions. Understanding this process may unveil treatment targets for pathologies involving complement activation and NET formation.

Placental neutrophil reverse trans-migration and maternal serum neutrophil extracellular trap expression in HIV infection co-morbid pre-eclampsia in women of African ancestry

Neutrophil extracellular traps (NETs) and placental neutrophil reverse transmigration (r-TM) are implicated in the pathogenesis of pre-eclampsia (PE). However, the role of the comorbidity of PE and human immunodeficiency virus (HIV) infection in placental neutrophil r-TM and serum NETs remains unknown. Human placental tissue (n = 160) and serum (n = 80) samples were obtained post-ethical approval and divided by pregnancy type and HIV status and across the study population. Immunohistochemistry and morphometry were performed to localize and quantify junctional adhesion molecule-C (JAM-C) expression as an inverse marker of neutrophil r-TM within placental villi. An enzyme-linked immunosorbent assay (ELISA) was performed to quantify the concentration of citrullinated histone H3 (cit-H3) as a marker of NETs. GraphPad Prism (version 8.0.2) was used to compare the results, and a p value of p < 0.05 was considered statistically significant. The localization of JAM-C was observed on the syncytiotrophoblasts (STBs) and endothelial cells of placental villi. The immunoexpression of JAM-C was elevated in PE vs. normotensive (N) placentae. In the exchange villi, JAM-C immunoexpression was higher in the N+ve vs. N-ve group. However, in PE comorbid HIV infection, JAM-C expression was lower in the PE+ve vs. PE-ve group. Citrullinated histone-H3 concentration was lower in the N+ve vs. N-ve group but elevated in early-onset PE (EOPE)+ve vs. late-onset PE (LOPE)+ve group. These results indicate that PE and HIV-infected placentae individually express elevated JAM-C, manifesting in less neutrophil r-TM. However, in exchange villi of PE comorbid with HIV infection reduced JAM-C enhances neutrophil r-TM, thus supporting the synergistic effect of PE comorbid with HIV.

A combined model of serum neutrophil extracellular traps, CD8+ Tcells, and tumor proportion score provides better prediction of PD-1 inhibitor efficacy in patients with NSCLC.

Immune checkpoint inhibitors provide a definite survival benefit for patients with driver-negative advanced non-small cell lung cancer (NSCLC), but predictors of efficacy are still lacking. There may be a relationship between immune inflammatory state and tumor immune response. We explored the relationship of serum neutrophil extracellular traps (NETs) with infiltrating cells in the tumor tissues of patients with NSCLC as well as their relationship with the therapeutic efficacy of programmed cell death protein 1 (PD-1) inhibitors. Serum myeloperoxidase (MPO)-double-stranded DNA (dsDNA) was detected as a marker of NET serum concentration. Tcells were detected by immunohistochemical staining, and neutrophils were counted by MPO immunofluorescence staining. Of the 31 patients with NSCLC, a longer progression-free survival after PD-1 inhibitor treatment was associated with higher levels of CD3+ Tcells, a lower neutrophil : CD3+-T-cell ratio (NEU/CD3+) and lower neutrophil : CD8+-T-cell ratio (NEU/CD8+) in tumor tissues. Patients with higher serum NETs were more likely to develop progressive disease after treatment (P = 0.003) and to have immune-related adverse events (IrAEs) as well as higher NEU/CD3+ and NEU/CD8+. The combined model of serum NETs, CD8+ Tcells, and tumor proportion score (TPS) significantly improved the prediction of PD-1 inhibitor efficacy [P = 0.033; area under the curve (AUC) = 0.881]. Our results indicate that serum NETs are effective predictors of PD-1 inhibitor response and reflect the tissue neutrophil-to-lymphocyte ratio and IrAE levels. The combined model of serum NETs, CD8+ Tcells, and TPS is a powerful tool for predicting the efficacy of PD-1 inhibitor treatment in patients with NSCLC.

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

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. 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. 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). 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.

Association of neutrophil extracellular trap levels with Raynaud’s phenomenon, glomerulonephritis and disease index score in SLE patients from Brazil

Neutrophil extracellular traps (NETs) are cell-extruded DNA strands coated with neutrophils' nuclear proteins and enzymes from cytotoxic granules, produced by NETosis, a cell death pathway. They perform an important defensive role in innate immunity, but their increased production and/or inefficient degradation expose new antigens, such as DNA or citrullinated histone peptides, triggering autoimmunity. This study aimed to access possible associations between serum NETs levels with epidemiological, clinical, and serological data from a well-characterized SLE Brazilian patients’ cohort. NET levels were evaluated in one hundred seventy serum samples of patients with Systemic Lupus Erythematosus (SLE) using an Immunoassay. Univariate and multivariate binary logistic regression used clinical patients' data as independent variables. Parametric and non-parametric tests compared log10 base serum NET levels transformed between patients' groups. SLE patients were also dichotomized into “High serum NET levels” and “Low serum NET levels” groups. All analyses were performed in R language 4.1.2, and p < 0.05 were considered significant. Increased susceptibility for high serum NET levels was observed in SLE patients with Raynaud's phenomenon (OR = 2.30, 95 % CI = 1.06–5.21 and p = 0.039), independently of any other risk factor. Also, SLE patients with Raynaud's phenomenon presented higher mean NET serum levels (mean = −0.13 vs. −0.51, p = 0.01). In addition, higher mean NET serum levels were associated with glomerulonephritis (mean = -0.45 vs. −0.12, p = 0.03). Ultimately, the SLEDAI index scored higher in the high NETs serum levels group (median = 2.0 vs. 0.0, p = 6 × 10−3). The formation of NETs might be implicated in Raynaud's phenomenon, glomerulonephritis, and disease index score in SLE patients. Our results highlight the importance of serum NET levels as a possible therapeutical target to modulate the clinical course of SLE.

Measurement of Neutrophil Extracellular Traps as a Biomarker for the Differential Diagnosis Between Antineutrophil Cytoplasmic Antibody-Positive Individuals With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis and Nonautoimmune Diseases.

Neutrophil extracellular traps (NETs) have a correlation with disease activity in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). However, it is not known whether there is an association between NETs and the presence of ANCA in other diseases. This study aimed to assess the occurrence of NETs in individuals with ANCA and whether serum NET quantitation is capable of distinguishing them with regard to the diagnosis. This was a cross-sectional, observational study. From the positive ANCA by indirect immunofluorescence, 94 individuals were divided into groups: AAV, infectious diseases, and neoplastic diseases. Healthy controls served for comparisons. Neutrophil extracellular traps were evaluated through the investigation of NET remnants, by detecting cell-free DNA bound to proteins such as histone, myeloperoxidase, and neutrophil elastase (NE). In patients with perinuclear ANCA (p-ANCA) the detection of NETs by NE was able to distinguish AAV from infection/neoplasia and healthy controls. Receiver operating characteristic curves for serum NETs by NE in patients with p-ANCA were drawn in 2 situations: AAV versus infection/neoplasia, showing a sensitivity of 0.65 and specificity of 0.84, with an area under the curve of 65%; and AAV versus controls, showing a sensitivity of 0.84 and a specificity of 0.88, with an area under the curve of 96%. For p-ANCA-positive individuals, we found higher serum NETs detected by NE-DNA in those with chronic infectious and neoplastic diseases than in AAV individuals and healthy controls. This allows us to infer that the evaluation of serum NETs may be of value as a biomarker for differential diagnosis.

Effect mechanism investigation of herb-partitioned moxibustion on relieving colon inflammation in Crohn disease rats based on neutrophil extracellular traps

ObjectiveTo explore the mechanism of herb-partitioned moxibustion in relieving rat intestinal inflammation by focusing on the neutrophil extracellular traps (NETs) in Crohn disease (CD) development.MethodsRats were randomly divided into a normal group, a model group, a herb-partitioned moxibustion group, and a mesalazine group. The CD rat model was prepared with 2,4,6-trinitrobenzene sulfonic acid except for rats in the normal group. Rats in the normal group and model group did not receive any treatment but had the same fixation as the other groups. Rats in the herb-partitioned moxibustion group received herb-partitioned moxibustion at Qihai (CV6) and bilateral Tianshu (ST25). Rats in the mesalazine group received intragastric administration of mesalazine enteric-coated tablets. The general situation of rats in each group was recorded, and the histopathological changes in the colon were observed and scored by hematoxylin-eosin staining. The serum concentrations of NETs DNA (NETs-DNA), neutrophil elastase (NE)-DNA, and myeloperoxidase (MPO)-DNA were detected by ABC enzyme-linked immunosorbent assay, and the citrullinated histone 3 (citH3), MPO, and NE protein and mRNA expression levels in rat colon tissue were observed by immunofluorescence and real-time quantitative polymerase chain reaction.ResultsCompared with the normal group, the mucosal ulcer reached the muscularis, the epithelium was incomplete, the goblet cells decreased obviously with significant inflammatory cell infiltration in the colon; the colonic mucosa damage index (CMDI) score increased significantly (P<0.01); the serum NETs-DNA, NE-DNA, and MPO-DNA concentrations increased (P<0.05); the NE, citH3, and MPO protein and mRNA expression in the colonic tissues increased significantly in the model group (P<0.01 or P<0.05). Compared with the model group, the mucosal epithelium in the herb-partitioned moxibustion group and the mesalazine group was repaired and the goblet cells increased with a few infiltrating inflammatory cells in the colon; the CMDI score decreased (P<0.01); the serum NETs-DNA, NE-DNA, and MPO-DNA concentrations decreased (P<0.05); the NE, citH3, and MPO protein and mRNA expression in the colonic tissues was down-regulated (P<0.01 or P<0.05).ConclusionHerb-partitioned moxibustion reduced the serum NETs complex and inhibited the protein and mRNA expression of NETs complex in the colon tissue, which may be one mechanism of herb-partitioned moxibustion in relieving colon mucosal inflammation in CD.

Neutrophil extracellular trap burden correlates with the stenosis of coronary atherosclerosis.

Coronary atherosclerosis diseases (CADs) are associated with chronic inflammation. Neutrophil extracellular traps (NETs) are a type of novel proinflammatory cytokines whose levels are dramatically elevated in acute coronary syndrome. We conducted this study to further evaluate the association between circulating NET-associated markers and CAD in Chinese adults. A total of 174 patients with CAD and 55 healthy controls were screened using percutaneous coronary intervention or coronary computed tomography angiography. Blood lipid levels, blood glucose levels, and blood cell counts were determined using commercial kits. Serum levels of myeloperoxidase (MPO) and neutrophil elastase (NE) were measured using ELISA. Double-stranded DNA (dsDNA) in serum was quantified using the Quant-iT PicoGreen assay. We also compared the circulating NET levels with various parameters in the study subjects. The levels of serum NET markers, dsDNA, MPO, and NE, were significantly elevated in patients with CAD, particularly in the severe group, consistent with the increase in neutrophil counts. The levels of NET markers correlated with the risk factors of AS, increasing with the number of risk factors. NET markers were identified as independent risk factors for severe coronary stenosis and also as predictors of severe CAD. NETs may be related to AS and serve as indicators or predictors of stenosis in patients with severe CAD.

Interferon alpha-2 treatment reduces circulating neutrophil extracellular trap levels in myeloproliferative neoplasms.

Neutrophil extracellular traps (NETs) may play a pathogenic role in the thrombosis associated with myeloproliferative neoplasms (MPNs). We measured serum NET levels in 128 pretreatment samples from patients with MPNs and in 85 samples taken after 12 months of treatment with interferon alpha-2 (PEG-IFNα-2) formulations or hydroxyurea (HU). No differences in NET levels were observed across subdiagnoses or phenotypic driver mutations. In PV, a JAK2V617F+ allele burden ≥50% associated with increased NET levels (p = 0.006). Baseline NET levels correlated with neutrophil count (r = 0.29, p = 0.001), neutrophil-to-lymphocyte ratio (r = 0.26, p = 0.004) and JAK2V617F allele burden (r = 0.22, p = 0.03), particularly in patients with PV and with allele burden ≥50% (r = 0.50, p = 0.01, r = 0.56, p = 0.002 and r = 0.45, p = 0.03 respectively). In PV, after 12 months of treatment, NET levels decreased on average by 60% in patients with allele burden ≥50%, compared to only 36% in patients with an allele burden <50%. Overall, treatment with PEG-IFNα-2a or PEG-IFNα-2b reduced NETs levels in 77% and 73% of patients, respectively, versus only 53% of HU-treated patients (average decrease across treatments: 48%). Normalization of blood counts did not per se account for these reductions. In conclusion, baseline NET levels correlated with neutrophil count, NLR and JAK2V617F allele burden, and IFNα was more effective at reducing prothrombotic NET levels than HU.

Influence factors of deep venous thromboembolism after knee arthroplasty and significance of changes of serum nets and sVCAM-1 levels

To investigate the relationship between the changes of serum neutrophil extracellular traps (NETs), soluble vascular cell adhesion molecule-1(sVCAM-1) and deep venous thromboembolism after knee arthroplasty. From May 2017 to April 2020, 30 patients with deep venous thromboembolism after knee arthroplasty were retrospectively selected as the observation group, and 60 patients without deep venous thromboembolism after knee arthroplasty in the same period were randomly selected as the control group. The clinical data, serum levels of nets and sVCAM-1 before and 1, 3 and 5 days after operation were compared between the two groups. Logistic regression model was used to analyze the influencing factors of deep venous thromboembolism after knee arthroplasty; Pearson correlation was used to analyze the relationship between serum nets and sVCAM-1 levels;Draw the receiver operating characteristic curve(ROC) to obtain the area under the curve(AUC), and analyze the diagnostic value of serum nets and sVCAM-1 levels for deep vein thromboembolism after knee arthroplasty. There were statistically significant differences between two groups in age, body mass index, and postoperative knee elevation and flexion ratio(P<0.05). The level of serum NETs and sVCAM-1 on the 1st and 3rd day after surgery of the observation group were higher than the control group(P<0.05). Logistic regression analysis showed that age, body mass index, knee flexion position, serum nets and sVCAM-1 levels at 1 and 3 days after operation were all the influencing factors of DVT after knee arthroplasty (P<0.05);Pearson correlation analysis showed that there was a positive correlation between the levels of serum NETs and sVCAM-1 in patients with deep venous thromboembolism after knee arthroplasty 1 and 3 days after operation(P<0.05). The ROC curve of predicting deep venous thromboembolism after knee arthroplasty by serum nets and sVCAM-1 levels at 1 and 3 days after operation was drawn, the results showed that the AUC of serum nets and sVCAM-1 levels at 1 day after operation was higher than that at 3 days after operation, which had a good predictive effect. The influencing factors of deep vein thromboembolism after knee arthroplasty are age, body mass index, postoperative knee elevation and flexion, postoperative serum NETs and sVCAM-1 levels, especially postoperative serum NETs and sVCAM-1 levels. Changes can be used as potential biomarkers for predicting postoperative deep vein thromboembolism, and clinical attention should be paid to it.

Blood neutrophil extracellular traps: a novel target for the assessment of mammary health in transition dairy cows

BackgroundMammary health is important for transition dairy cows and has been well recognized to exert decisive effects on animal welfare. However, the factors influencing mammary health are still unclear. Differential somatic cell count (DSCC) could reflect the mastitis risk since it is the percentage of neutrophils plus lymphocytes in total somatic cells and could be reflective of mammary health of dairy cows. This work aimed to investigate the assessment and prognosis of the health of transition cows based on blood neutrophil extracellular traps (NETs).ResultsEighty-four transition Holstein dairy cows were selected. The serum was sampled in all the animals at week 1 pre- and postpartum, and milk was sampled at week 1 postpartum. Based on the DSCC in milk at week 1, cows with lower (7.4% ± 4.07%, n = 15) and higher (83.3% ± 1.21%, n = 15) DSCCs were selected. High DSCC cows had higher levels of red blood cell counts (P < 0.05), hemoglobin (P = 0.07), and hematocrit (P = 0.05), higher concentrations of serum oxidative variables [(reactive oxygen species (P < 0.05), malondialdehyde (P < 0.05), protein carbonyl (P < 0.05), and 8-hydroxy-2-deoxyguanosine (P = 0.07)], higher levels of serum and milk NETs (P < 0.05) and blood-milk barrier indicators, including serum β-casein (P = 0.05) and milk immunoglobulin G2 (P = 0.09), than those of low DSCC cows. In addition, lower concentrations of serum nutrient metabolites (cholesterol and albumin) (P < 0.05) and a lower level of serum deoxyribonuclease I (P = 0.09) were observed in high DSCC cows than in low DSCC cows. Among the assessments performed using levels of the three prepartum serum parameters (NETs, deoxyribonuclease I and β-casein), the area under the curve (0.973) of NETs was the highest. In addition, the sensitivity (1.00) and specificity (0.93) were observed for the discrimination of these cows using NETs levels with a critical value of 32.2 ng/mL (P < 0.05).ConclusionsThe formation of NETs in blood in transition dairy cows may damage the integrity of the blood-milk barrier and thereby increase the risk for mastitis in postpartum cows.

Interferon-alpha2 Treatment Reduces Circulating Neutrophil Extracellular Trap Levels in Myeloproliferative Neoplasms

Background and aim Arterial and venous thrombosis are major life-threatening events for patients with Philadelphia-negative chronic myeloproliferative neoplasms (MPNs). Neutrophil activation and, in particular, the formation of neutrophil extracellular traps (NETs) have been implicated in the pathogenesis of MPNs and thrombosis, particularly in patients with the most common MPN phenotypic driver mutation, JAK2V617F. Moreover, ruxolitinib treatment reduces ex vivo NET formation in JAK2V617F-positive patients with MPNs. In this study, we aimed to clarify the effect of interferon alpha (IFNα) and hydroxyurea (HU) treatment on the levels of circulating NETs in patients with MPNs. Methods Serum NET (myeloperoxidase-DNA complexes) levels were measured using an in-house ELISA in pre-treatment samples collected from 128 patients with MPNs enrolled in the DALIAH trial (NCT01387763), a randomized controlled phase 3 clinical study. NETs were likewise quantified in 85 paired samples collected after 12 months of therapy with HU or either of two different formulations of pegylated IFNα (PEG-IFNα2a or PEG-IFNα2b). Results At baseline, NET levels did not vary significantly between patients with different MPN sub-diagnoses (ET: 48, PV: 61, Pre-MF: 10, PMF: 9), phenotypic driver mutations (JAK2V617F, CALR, MPL, or triple negative), or between those with or without a history of major thrombosis. However, patients with PV and a JAK2V617F allele burden ≥ 50% at baseline had significantly higher baseline NET levels than those with an allele burden < 50% (p=0.006). NET levels at baseline correlated significantly with neutrophil count (r=0.29, p=0.001), neutrophil-to-lymphocyte ratio (NLR)(r=0.26, p=0.004) and JAK2V617F allele burden (r=0.22, p=0.03), particularly in patients with PV and allele burden ≥ 50% (r=0.50, p=0.01, r=0.56, p=0.007 and r=0.45, p=0.03 respectively), while the same was not observed at follow-up. Furthermore, after 12 months of treatment, NET levels decreased in 70% of patients, with an average decrease of 48%, compared to baseline levels. The effect of treatment was particularly pronounced in patients with PV with an allele burden ≥ 50%, of whom 76% showed decreased NET levels, with an average decrease of 60%, while 67% of patients with allele burden < 50% showed an average reduction in NET levels of only 36% (Figure 1). While 77% and 73% of patients treated with PEG-IFNα-2a or PEG-IFNα-2b, respectively, had decreased NET levels, the same applied to only 53% of patients treated with HU (Figure 2). Discussion and conclusion The increased NET levels in patients with PV with a JAK2V617F allele burden ≥ 50% indicate that the JAK/STAT pathway is involved in NET formation and/or clearance. In keeping with this, the highest proportion of patients with decreased NET levels after treatment and the highest average decrease were seen in patients with PV and a baseline JAK2V617F allele burden ≥ 50%. NET levels at baseline correlated with neutrophil count and NLR, however normalization of blood counts alone did not account for the observed decrease in NET levels. Accordingly, treatment with IFNα, which has previously been shown to target the JAK2V617F clone preferentially, effectively reduced circulating NET levels, and to a greater extent than HU treatment. This may relate to our previous finding that three months' IFNα2 treatment downregulates the expression of PAD4, which is implicated in NET formation. Although, we found no difference in NET levels in patients with and without a history of major thrombotic events, these data suggest that IFNα2 treatment, by reducing levels of potentially prothrombotic NET, may contribute to reduced risk of this complication in patients with MPNs, and that it is an advantageous treatment compared to HU in this respect. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Elevated neutrophil extracellular traps by HBV-mediated S100A9-TLR4/RAGE-ROS cascade facilitate the growth and metastasis of hepatocellular carcinoma.

Neutrophil extracellular traps (NETs) are considered significant contributors to cancer progression, especially metastasis. However, it is still unclear whether NETs are involved in hepatitis B virus (HBV)-related hepatocarcinogenesis and have potential clinical significance during evaluation and management for hepatocellular carcinoma (HCC). In this study, we aimed to investigate the functional mechanism of NETs in HBV-related hepatocarcinogenesis and their clinical significance. A total of 175 HCC patients with and without HBV infection and 58 healthy controls were enrolled in this study. NETs were measured in tissue specimens, freshly isolated neutrophils and blood serum from these patients, and the correlation of circulating serum NETs levels with malignancy was evaluated. The mechanism by which HBV modulates NETs formation was explored using cell-based studies. In addition, in vitro and in vivo experiments were further performed to clarify the functional mechanism of NETs on the growth and metastasis of HCC. We observed an elevated level of NETs in blood serum and tissue specimens from HCC patients, especially those infected with HBV. NETs facilitated the growth and metastasis of HCC both in vitro and in vivo, which were mainly dominated by increased angiogenesis, epithelial-mesenchymal transition (EMT)-related cell migration, matrix metalloproteinases (MMPs)-induced extracellular matrix (ECM) degradation and NETs-mediated cell trapping. Inhibition of NETs generation by DNase 1 effectively abrogated the NETs-aroused HCC growth and metastasis. In addition, HBV-induced S100A9 accelerated the generation of NETs, which was mediated by activation of toll-like receptor (TLR4)/receptor for advanced glycation end products (RAGE)-reactive oxygen species (ROS) signaling. Further, circulatory NETs were found to correlate with viral load, TNM stage and metastasis status in HBV-related HCC, and the identified NETs could predict extrahepatic metastasis, with an area under the ROC curve (AUC) of 0.83 and 90.3% sensitivity and 62.8% specificity at a cutoff value of 0.32. Our findings indicated that activation of RAGE/TLR4-ROS signaling by HBV-induced S100A9 resulted in abundant NETs formation, which subsequently facilitated the growth and metastasis of HCC cells. More importantly, the identified circulatory NETs exhibited potential as an alternative biomarker for predicting extrahepatic metastasis in HBV-related HCC.

Serum extracellular traps associate with the activation of myeloid cells in SLE patients with the low level of anti-DNA antibodies

Neutrophil extracellular traps (NETs) are involved in systemic lupus erythematosus (SLE). We sought to cluster SLE patients based on serum NET levels. Serum NET levels were higher in SLE patients than healthy controls. Frequencies of pleuritis and myositis were increased in patients with high serum NET levels. Serum NET levels negatively correlated with anti–double stranded DNA (anti-dsDNA) antibody titers and C1q-binding immune complexes, but positively correlated with C-reactive protein (CRP) and monocyte counts. Neutrophil transcriptome analysis demonstrated no difference in NET-associated signatures, irrespective of serum NET levels, suggesting anti-dsDNA antibody-mediated clearance of NETs. In serum, NET levels were significantly correlated with myeloid cell-derived inflammatory molecules. Serum NET-based cluster analysis revealed 3 groups of patients based on serum NET and CRP levels, anti-dsDNA antibody titers, and monocyte count. Monocytes were consistently activated following NET-containing immune complex (NET-IC) stimulation. In conclusion, SLE patients with high serum NET levels had lower anti-dsDNA antibody titers and higher inflammatory responses. NET-IC-stimulated monocytes might associate with an inflammatory response characterized by elevated CRP levels. These findings can apply to precision medicine, as inflammatory processes, rather than antibody-dependent processes, can be targeted in specific subpopulations of SLE patients.

Quantitation of neutrophil extra cellular traps (NETs) in liver cirrhosis patients and their relation to the incidence of different complications

Backgrounds and aimNeutrophil extracellular traps (NETs) have been shown to play an important role in inflammatory and thrombotic processes. Investigating the presence of NETs in liver cirrhosis to detect any contribution to occurrence of complications may help predict or prevent those complications.MethodsAmong 78 cirrhotic patients, the serum NETs level was measured using ELISA and compared to different etiologies of liver cirrhosis (Viral, HCC, Bilharzial, NASH, cardiac cirrhosis and undetermined etiology) as well as markers of inflammation and complications in those patients.ResultsWe found that NETs are substantially found in LCF and have a significant relation to malignant portal vein thrombosis but not other studied complications or etiology of liver cirrhosis.ConclusionNETs however found in liver cirrhosis patients may not play as a significant role in occurrence of complications as thought. So, NETs cannot be reliably used as a biomarker or predictor for occurrence of thrombosis in liver cirrhosis patients.Lay summaryLiver cirrhosis patients have many factors at play that lead to development of thrombosis. NETS may play a role with the development of malignant thrombosis in those patients. Further evaluation for their level and action should be studied before considering NETs as a key player in development of complications.

Neutrophil Extracellular Traps Regulate HMGB1 Translocation and Kupffer Cell M1 Polarization During Acute Liver Transplantation Rejection.

Neutrophil extracellular traps (NETs) play important roles in hepatic ischemic reperfusion injury (IRI) and acute rejection (AR)-induced immune responses to inflammation. After liver transplantation, HMGB1, an inflammatory mediator, contributes to the development of AR. Even though studies have found that HMGB1 can promote NET formation, the correlation between NETs and HMGB1 in the development of AR following liver transplantation has not been elucidated. In this study, levels of serum NETs were significantly elevated in patients after liver transplantation. Moreover, we found that circulating levels of NETs were negatively correlated with liver function. In addition, liver transplantation and elevated extracellular HMGB1 promoted NET formation. The HMGB1/TLR-4/MAPK signaling pathway, which is initiated by HMGB1, participates in NET processes. Moreover, in the liver, Kupffer cells were found to be the main cells secreting HMGB1. NETs induced Kupffer cell M1 polarization and decreased the intracellular translocation of HMGB1 by inhibiting DNase-1. Additionally, co-treatment with TAK-242 (a TLR-4 inhibitor) and rapamycin more effectively alleviated the damaging effects of AR following liver transplantation than either drug alone.

Neutrophil Extracellular Traps in the Autoimmunity Context.

The formation of neutrophil extracellular traps (NETs) is a strategy utilized by neutrophils for capturing infective agents. Extracellular traps consist in a physical net made of DNA and intracellular proteins externalized from neutrophils, where bacteria and viruses are entrapped and killed by proteolysis. A complex series of events contributes to achieving NET formation: signaling from infectious triggers comes first, followed by decondensation of chromatin and extrusion of the nucleosome components (DNA, histones) from the nucleus and, after cell membrane breakdown, outside the cell. NETs are composed of either DNA or nucleosome proteins and hundreds of cytoplasm proteins, a part of which undergo post-translational modification during the steps leading to NETs. There is a thin balance between the production and the removal of circulating NETs from blood where digestion of DNA by circulating DNases 1 and IL3 has a critical role. A delay in NET removal may have consequences for autoimmunity. Recent studies have shown that circulating NET levels are increased in systemic lupus erythematosus (SLE) for a functional block of NET removal mediated by anti-DNase antibodies or, in rare cases, by DNase IL3 mutations. In SLE, the persistence in circulation of NETs signifies elevated concentrations of either free DNA/nucleosome components and oxidized proteins that, in some cases, are recognized as non-self and presented to B-cells by Toll-like receptor 9 (TLR9). In this way, it is activated as an immunologic response, leading to the formation of IgG2 auto-antibody. Monitoring serum NET levels represents a potential new way to herald the development of renal lesions and has clinical implications. Modulating the balance between NET formation and removal is one of the objectives of basic research that are aimed to design new drugs for SLE.Clinical Trial Registration Number: The Zeus study was registered at https://clinicaltrials.gov (study number: NCT02403115).

Neutrophil extracellular traps as a novel biomarker to predict recurrence-free and overall survival in patients with primary hepatic malignancies

BackgroundThe incidence of primary hepatic malignancies including Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) is on the rise. (i) Surgery remains the mainstay of potential curative treatment, however the vast majority of patients will recur and not be amenable to curative therapy. (ii) Inflammation has been associated with poor prognosis, however there is no preoperative marker that can predict recurrence-free- or overall survival. Our aim is to correlate inflammation measured as neutrophil extracellular traps (NETs) with survival. MethodsA retrospective analysis was performed using sera/tissue from patients with hepatic malignancies. NET levels were measured in the serum (MPO-DNA) or tumor (Cit-H3). Log rank analysis for RFS/OS was performed. ResultsCancer patients had higher pre-surgery MPO-DNA levels compared to healthy individuals (healthy vs cancer: 2.6 ± 1.0 ng/ml vs 34.7 ± 2.13 ng/ml; p < 0.0001). High pre-surgery serum NET levels were associated with shorter RFS/OS compared to those with low levels (RFS-HCC: HR: 2.91, 95% CI: 1.61–5.26, p < 0.0001, RFS-CC: HR: 3.22, 95% CI: 1.33–7.77 p < 0.0093). High Cit-H3 tumor levels similarly predicted shorter RFS/OS. ConclusionThe current study shows a correlation between pre-operative NET levels and survival. Studying NET formation as a biomarker pre-surgery can help identify patients that could benefit from closer follow-up due to higher risk for recurrence.

DNA of neutrophil extracellular traps promotes cancer metastasis via CCDC25.

Neutrophil extracellular traps (NETs), which consist of chromatin DNA filaments coated with granule proteins, are released by neutrophils to trap microorganisms1-3. Recent studies have suggested that the DNA component of NETs (NET-DNA) is associated with cancer metastasis in mouse models4-6. However, the functional role and clinical importance of NET-DNA in metastasis in patients with cancer remain unclear. Here we show that NETs are abundant in the liver metastases of patients with breast and colon cancers, and that serum NETs can predict the occurrence of liver metastases in patients with early-stage breast cancer. NET-DNA acts as a chemotactic factor to attract cancer cells, rather than merely acting as a 'trap' for them; in several mouse models, NETs in the liver or lungs were found to attract cancer cells to form distant metastases. We identify the transmembrane protein CCDC25 as a NET-DNA receptor on cancer cells that senses extracellular DNA and subsequently activates the ILK-β-parvin pathway to enhance cell motility. NET-mediated metastasis is abrogated in CCDC25-knockout cells. Clinically, we show that the expression of CCDC25 on primary cancer cells is closely associated with a poor prognosis for patients. Overall, we describe a transmembrane DNA receptor that mediates NET-dependent metastasis, and suggest that targeting CCDC25 could be an appealing therapeutic strategy for the prevention of cancer metastasis.

CRP Induces NETosis in Heart Failure Patients with or without Diabetes.

C-reactive protein (CRP) is recognized as a biomarker of chronic, low-grade inflammation associated with vascular disorders. Lately, the role of neutrophils and neutrophil extracellular traps (NETs) has been investigated as a potential source of chronic inflammation and cardiovascular complications. This study investigated NETs as a marker of inflammation in patients with symptomatic heart failure (HF) with or without type 2 diabetes (T2DM) and examined the correlation between NETs and CRP. We performed a noninterventional study including patients with HF with or without T2DM, T2DM, and a healthy control (HC) group. NETs and other inflammatory markers in serum were measured by ELISA. The release of NETs (NETosis) in vitro under various stimuli was measured by confocal microscopy. The levels of NETs in the serum of HF patients were significantly higher compared with HC (112%). Serum CRP concentrations were significantly increased in HF and HF plus T2DM patients compared with HC, and a positive correlation was observed between serum CRP and NETs levels. Neutrophils from HF and HF plus T2DM patients underwent in vitro NETs release faster than T2DM and HC without any stimuli. In vitro, serum collected from the HF and the HF plus T2DM group induced NETosis in healthy neutrophils significantly more when compared with HC and T2DM, which was prevented by depletion from CRP. We confirmed in vitro that CRP induces a concentration-dependent NETs synthesis. This study proposes a mechanism by which CRP increases the risk of future cardiovascular events and supports mounting evidences on the role of neutrophils in chronic low-grade inflammation associated with HF.