Neutrophil-Extracellular Traps, Cell-Free DNA, and Immunothrombosis in Companion Animals: A Review

Immunothrombosis is a potentially beneficial physiological process that aids innate immunity and host defense against pathogen invasion. However, this process can also be damaging when it occurs to excess or in critical blood vessels. Formation of extracellular traps by leukocytes, particularly neutrophils, is central to our understanding of immunothrombosis. In addition to degranulation and phagocytosis, extracellular traps are the third mechanism by which neutrophils combat potential pathogens. These traps consist of extracellular DNA decorated with bactericidal cellular proteins, including elastase, myeloperoxidase, and cathepsins. Neutrophils can release these structures as part of a controlled cell-death process or via a process termed vital NETosis that enables the cells to extrude DNA but remain viable. There is accumulating evidence that NETosis occurs in companion animals, including dogs, horses, and cats, and that it actively contributes to pathogenesis. Numerous studies have been published detailing various methods for identification and quantification of extracellular trap formation, including cell-free DNA, measurements of histones and proteins such as high-mobility group box–1, and techniques involving microscopy and flow cytometry. Here, we outline the present understanding of these phenomena and the mechanisms of extracellular trap formation. We critically review the data regarding measurement of NETosis in companion animals, summarize the existing literature on NETosis in veterinary species, and speculate on what therapeutic options these insights might present to clinicians in the future.

Download Full-text

Short-Term Treadmill Running as a Model for Studying Cell-Free DNA Kinetics In Vivo

Clinical Chemistry ◽

10.1373/clinchem.2010.158030 ◽

2011 ◽

Vol 57 (4) ◽

pp. 633-636 ◽

Cited By ~ 58

Author(s):

Thomas Beiter ◽

Annunziata Fragasso ◽

Jens Hudemann ◽

Andreas M Nieß ◽

Perikles Simon

Keyword(s):

Time Course ◽

Treadmill Exercise ◽

Plasma Concentrations ◽

High Mobility ◽

Treadmill Running ◽

Short Term ◽

Cell Free Dna ◽

Free Dna ◽

Cross Country

BACKGROUND Increased plasma concentrations of cell-free DNA (cf-DNA) are considered a hallmark of various clinical conditions. Despite intensive research in this field, limited data are available concerning the time course of release and clearance of cf-DNA in vivo. METHODS We extracted cf-DNA from plasma samples taken before and immediately after a 10-km cross-country run, and from samples taken before, immediately after, and 30 min after exhaustive short-term treadmill exercise. The contribution of nuclear (nDNA) and mitochondrial DNA (mtDNA) was measured by quantitative real-time PCR. The incremental treadmill exercise setup was exploited to delineate the precise sequencing and timing of cf-nDNA, lactate, and high-mobility group box 1 protein (HMGB1) release during the exercise and recovery phases. RESULTS Postexercise plasma cf-nDNA concentrations in cross-country and treadmill runners were significantly increased, by 7.6-fold and 9.9-fold, respectively (P < 0.001). cf-nDNA concentrations were not correlated with age, sex, or body mass index. Plasma concentrations of cf-nDNA and HMGB1 in postexercise samples of treadmill runners were significantly correlated (r = 0.84; P = 0.004). cf-mtDNA concentrations were not affected by treadmill exercise. Time-course analyses demonstrated that cf-nDNA is released within minutes after the onset of exercise and is rapidly cleared from the circulation after the cessation of exercise. Nearly congruent kinetics for cf-nDNA, lactate, and HMGB1 were observed during the exercise phase. CONCLUSIONS A single bout of exhaustive short-term treadmill exercise constitutes a versatile model system suitable for addressing basic questions about cf-DNA biology.

Download Full-text

Neutrophil Extracellular Traps May Contribute to the Pathogenesis in Adult-onset Still Disease

The Journal of Rheumatology ◽

10.3899/jrheum.181058 ◽

2019 ◽

Vol 46 (12) ◽

pp. 1560-1569 ◽

Cited By ~ 4

Author(s):

Mi-Hyun Ahn ◽

Jae Ho Han ◽

Young-Jun Chwae ◽

Ju-Yang Jung ◽

Chang-Hee Suh ◽

...

Keyword(s):

Immunohistochemical Analysis ◽

Serum Levels ◽

Neutrophil Extracellular Traps ◽

Polymorphonuclear Neutrophils ◽

Adult Onset ◽

Cell Free Dna ◽

Extracellular Traps ◽

Free Dna ◽

Still Disease

Objective.Release of neutrophil extracellular traps (NET) has been described as an effector mechanism of polymorphonuclear neutrophils in several inflammatory diseases. Thus, this study was performed to evaluate the role of NET in the pathogenesis of adult-onset Still disease (AOSD).Methods.We determined the serum levels of NET molecules and investigated their associations with clinical disease activities in patients with AOSD. Further, we analyzed the differences in the NETosis response in AOSD patients compared to healthy controls (HC). To explore the in vivo involvement of NET in AOSD, we performed immunohistochemical analysis of skin and lymph node (LN) biopsies for proteins related to NET in patients with active AOSD.Results.Serum levels of cell-free DNA, myeloperoxidase (MPO)-DNA complex, and α-defensin were significantly increased in patients with AOSD compared to HC. Serum levels of the NET molecules, cell-free DNA, MPO-DNA, and α-defensin were correlated with several disease activity markers for AOSD. In followup of patients with AOSD after treatment with corticosteroid, the levels of cell-free DNA and α-defensin decreased significantly. On immunohistochemistry, neutrophil elastase–positive and MPO-positive inflammatory cells were detected in skin and LN of patients with AOSD, and were expressed in fiber form in the lesions. The serum from patients with active AOSD induced NETosis in neutrophils from HC. NET molecules induced interleukin 1β production in monocytes, representing a novel mechanism in the pathogenesis of AOSD.Conclusion.The findings presented here suggest that NET may contribute to the inflammatory response and pathogenesis in AOSD.

Download Full-text

Quantification of plasma cell-free DNA levels in dogs with various tumors

Journal of Veterinary Diagnostic Investigation ◽

10.1177/1040638719880245 ◽

2019 ◽

Vol 31 (6) ◽

pp. 836-843 ◽

Cited By ~ 7

Author(s):

Michihito Tagawa ◽

Genya Shimbo ◽

Hisashi Inokuma ◽

Kazuro Miyahara

Keyword(s):

Disease Progression ◽

Distant Metastasis ◽

Malignant Tumors ◽

Clinical Stage ◽

Extracellular Dna ◽

Dna Integrity ◽

Healthy Controls ◽

Cell Free Dna ◽

Free Dna ◽

Integrity Index

Circulating cell-free DNA (cfDNA) is extracellular DNA released into the bloodstream by apoptotic or necrotic tumor cells, with cfDNA determination proposed as a noninvasive, sensitive marker for the diagnosis of human cancer. We evaluated cfDNA quantification as a diagnostic and prognostic tool in dogs with various tumors. We quantified plasma cfDNA concentration by absolute real-time PCR of long interspersed nuclear elements in 50 dogs with malignant tumors, 13 dogs with benign tumors or nodules, and 11 healthy controls. Six patients with malignant tumors were followed-up, and plasma cfDNA was quantified throughout disease progression. We found that plasma cfDNA concentrations were significantly elevated in dogs with malignant tumors compared with dogs with benign nodules or healthy controls. The DNA integrity index (the ratio between long and short cfDNA fragments) was significantly lower in dogs with malignant tumors compared to healthy controls. Significantly higher cfDNA levels and a lower DNA integrity index were observed in dogs with lymphoma or leukemia, hemangiosarcoma, and distant metastasis; cfDNA levels correlated well with clinical stage and tended to increase during or before periods of disease progression, suggesting potential efficacy of cfDNA for the detection of distant metastasis and to monitor the clinical stage of neoplasia.

Download Full-text

Circulating Neutrophil Extracellular Traps in the Pathogenesis of Acute Chest Syndrome of Sickle Cell Disease

Blood ◽

10.1182/blood-2019-130574 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3556-3556

Author(s):

Ravi Vats ◽

Egemen Tutuncuoglu ◽

Jesus Tejero ◽

Cheryl A Hillery ◽

Mark T Gladwin ◽

...

Keyword(s):

Sickle Cell Disease ◽

Lung Injury ◽

Sickle Cell ◽

Neutrophil Extracellular Traps ◽

Acute Chest Syndrome ◽

Cell Disease ◽

Cell Free Dna ◽

Extracellular Traps ◽

Free Dna ◽

Platelet Aggregates

Introduction: Acute chest syndrome (ACS) is a type of acute lung injury and among the primary reasons for mortality and morbidity among Sickle Cell Disease (SCD) patients. Although epidemiologic evidence suggests that vaso-occlusion in the lung may serve as an antecedent to ACS, the cellular, molecular and biophysical mechanism of ACS is incompletely understood. Our recent findings revealed that the lung vaso-occlusion is enabled by the entrapment of embolic neutrophil-platelet aggregates in the pulmonary arterioles of transgenic humanized SCD mice. Recent evidence also suggests a role for neutrophil extracellular traps (NETs) in ACS. NETs are web-like structures of decondensed nuclear DNA decorated with citrullinated-histones (H3-cit) and neutrophil granule proteins. Interestingly, circulating nucleosomes and NETs fragments are elevated in SCD patient blood and the levels correlate with onset of ACS, however, the molecular mechanism that promotes generation of circulating NETs and the role of circulating NETs in promoting ACS remains poorly understood. Materials and Methods: Townes knock-in humanized SS (hα/hα:βS/βS) and AS (hα/hα:βA/βS) mice were used as SCD and control mice, respectively. SS and AS mice were intravenously (IV) administered 10 µmole/kg Oxy-Hb followed by Sytox orange, FITC-dextran or fluorescent anti-mouse mAbs against Ly6G, CD49b, H3cit, and neutrophil elastase for in vivo visualization of extracellular DNA, blood vessels, neutrophils, platelets and NETs, respectively. Pulmonary microcirculation was monitored using multi-photon-excitation enabled quantitative fluorescence intravital lung microscopy (qFILM). Results and Discussion: IV Oxy-Hb triggered the occlusion of pulmonary arterioles by neutrophil-platelet aggregates leading to loss of pulmonary blood flow in SCD but not control mice. Surprisingly, pulmonary vaso-occlusion in SCD mice was accompanied by the arrival of circulating cell free DNA (CFD) and NETs fragments into the pulmonary circulation. The cell free DNA (CFD) and NETs fragments entered the lung through the arterial circulation suggesting that they originated outside of lung. These cell free DNA (CFD) and NETs fragments contributed to lung vaso-occlusion and injury by promoting neutrophil-platelet aggregation in the lung arterioles. Conclusion: These findings reveal for the first time that circulating cell free DNA (CFD) and NETs fragments originating outside of lung contribute to pathogenesis of ACS. Currently, experiments are underway to identify the innate immune pathways that promote circulating NETs dependent lung injury in SCD. Disclosures Gladwin: Globin Solutions, Inc: Patents & Royalties: Provisional patents for the use of recombinant neuroglobin and heme-based molecules as antidotes for CO poisoning; United Therapeutics: Patents & Royalties: Co-inventor on an NIH government patent for the use of nitrite salts in cardiovascular diseases ; Bayer Pharmaceuticals: Other: Co-investigator.

Download Full-text

Properties and Application of Cell-Free DNA as a Clinical Biomarker

International Journal of Molecular Sciences ◽

10.3390/ijms22179110 ◽

2021 ◽

Vol 22 (17) ◽

pp. 9110

Author(s):

Felipe Silva de Miranda ◽

Valério Garrone Barauna ◽

Leandro dos Santos ◽

Gustavo Costa ◽

Paula Frizera Vassallo ◽

...

Keyword(s):

Clinical Practice ◽

Venous Blood ◽

Endothelial Damage ◽

Extracellular Dna ◽

Release Mechanism ◽

Blood Collection ◽

Cell Free Dna ◽

Molecular Features ◽

Free Dna ◽

Clinical Biomarker

Biomarkers are valuable tools in clinical practice. In 2001, the National Institutes of Health (NIH) standardized the definition of a biomarker as a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention. A biomarker has clinical relevance when it presents precision, standardization and reproducibility, suitability to the patient, straightforward interpretation by clinicians, and high sensitivity and/or specificity by the parameter it proposes to identify. Thus, serum biomarkers should have advantages related to the simplicity of the procedures and to the fact that venous blood collection is commonplace in clinical practice. We described the potentiality of cfDNA as a general clinical biomarker and focused on endothelial dysfunction. Circulating cell-free DNA (cfDNA) refers to extracellular DNA present in body fluid that may be derived from both normal and diseased cells. An increasing number of studies demonstrate the potential use of cfDNA as a noninvasive biomarker to determine physiologic and pathologic conditions. However, although still scarce, increasing evidence has been reported regarding using cfDNA in cardiovascular diseases. Here, we have reviewed the history of cfDNA, its source, molecular features, and release mechanism. We also show recent studies that have investigated cfDNA as a possible marker of endothelial damage in clinical settings. In the cardiovascular system, the studies are quite new, and although interesting, stronger evidence is still needed. However, some drawbacks in cfDNA methodologies should be overcome before its recommendation as a biomarker in the clinical setting.

Download Full-text

Neutrophil extracellular traps and thrombosis in COVID-19

10.1101/2020.04.30.20086736 ◽

2020 ◽

Cited By ~ 23

Author(s):

Yu Zuo ◽

Melanie Zuo ◽

Srilakshmi Yalavarthi ◽

Kelsey Gockman ◽

Jacqueline A. Madison ◽

...

Keyword(s):

Inflammatory Diseases ◽

Histone H3 ◽

Neutrophil Extracellular Traps ◽

Neutrophil Extracellular Trap ◽

Dna Complexes ◽

Extracellular Traps ◽

Free Dna ◽

Extracellular Trap ◽

Net Release ◽

D Dimer

ABSTRACTHere, we report on four patients whose hospitalizations for COVID-19 were complicated by venous thromboembolism (VTE). All demonstrated high levels of D-dimer as well as high neutrophil-to-lymphocyte ratios. For three patients, we were able to test sera for neutrophil extracellular trap (NET) remnants and found significantly elevated levels of cell-free DNA, myeloperoxidase-DNA complexes, and citrullinated histone H3. Neutrophil-derived S100A8/A9 (calprotectin) was also elevated. Given strong links between hyperactive neutrophils, NET release, and thrombosis in many inflammatory diseases, the potential relationship between NETs and VTE should be further investigated in COVID-19.

Download Full-text